SEED
Reference Manual

Standard for the Exchange of Earthquake Data
SEED Format Version 2.4
August, 2012

International Federation of Digital Seismograph Networks
Incorporated Research Institutions for Seismology
United States Geological Survey

This reference manual is published by the Incorporated Research Institutions for Seismology (IRIS).
SEED was jointly developed by members of the Federation of Digital Seismographic Networks (FDSN).
We welcome your questions and suggestions. For more information concerning this reference manual or
the SEED format, contact:
Dr. Timothy K. Ahern
IRIS
1408 NE 45th Street
Second Floor
Seattle, WA 98105(206) 547-0393

Dr. Bernard Dost
ORFEUS Data Center
P.O.Box 201
3730 AE De Bilt
The Netherlands+31 (0)30 2206 340

Printing History: First Edition - March 1990
		Second Edition - February 1993
		
Third Edition - March 2006
Electronic Release: January 2009
Credits: Initial design:		
Initial Implementation,
and Documentation:
Documentation:						Second Edition
				
Third Edition		
				
				
				
				
Electronic Release

Ray Buland, United States Geological Survey
Scott Halbert of the USGS performed the initial documentation.
Tim Ahern, Incorporated Research Institutions for Seismology
Ray Styles, Science Information Associates, Inc.
Tim Ahern, Incorporated Research Institutions for Seismology
Kris Skjellerup, Incorporated Research Institutions for Seismology
Tim Ahern, Incorporated Research Institutions for Seismology
Rob Casey, Incorporated Research Institutions for Seismology
Deborah Barnes, Incorporated Research Institutions for Seismology
Rick Benson, Incorporated Research Institutions for Seismology
Tim Knight, Incorporated Research Institutions for Seismology
Chad Trabant, Incorporated Research Institutions for Seismology

Contents
Chapter 1. Introducing SEED1

What is SEED?
1
SEED’s Background
1
A Description of SEED Format Versions2
What This Manual Covers
6
Acknowledgments7
Introduction to the Format
7
Design Goals and Strategies
8
Recommended Uses
11
Conventions12

Chapter 2. An Overview of SEED13

Format Organization
13
Physical and Logical Volumes
14
Format Objects
14
Control Headers
14
Blockettes16
Data Records
18
How to Write SEED Data
19
Procedure to Write Field Station Volumes
19
Procedure to Write Station and Event Oriented Network Volumes
22
Field Station Volumes
24
Merging Field Station Volumes into Network Volumes
27
Telemetry Volumes and Electronic Data Transmission
27
Software28

Chapter 3. SEED Conventions
ASCII Header Field ConventionsHow to Assemble Control Headers
How Binary Data Fields are Described in This Manual

Chapter 4. Volume Index Control Headers

29
29
32
33

35

Chapter 5. Abbreviation Dictionary Control Headers

41

Chapter 6. Station Control Headers

63

Chapter 7. Time Span Control Headers

99

Chapter 8. Data Records

107

Glossary129
Appendices
A: Channel Naming
B: Compression Algorithms
C: Specifying and Using Channel Response Information
D: The Data Description Language
E: Sample Logical Volumes
F: Cross Reference for Fields in Abbreviation Dictionaries
G: Data Only SEED Volumes (Mini-SEED)
H: omitted
I: omitted
J: Network Codes
L: FDSN Usage

133
141
151
171
185
193
195
199
201
203
213

Bibliography217
Index219

Chapter 1

Chapter 1

Introducing SEED
What is SEED?
The Standard for the Exchange of Earthquake Data (SEED) is an international standard format for the exchange ofdigital seismological data. SEED was designed for use by the earthquake research community, primarily for theexchange between institutions of unprocessed earth motion data. It is a format for digital data measured at one point inspace and at equal intervals of time.
SEED helps seismologists who record, share, and use seismological data. By providing a standard, SEED makes transmitting, receiving, and processing earthquake data easier and more accurate. Before the introduction of SEED, easeand accuracy had been goals, but not really attained.

SEED’s Background
Before the 1970’s, analog media (usually paper or film) were the sole means of recording seismic data. When researchers wanted to exchange this recorded data, they had to deliver the original seismogram recordings or copies. Whenthey needed to describe important associated information about a recording, they would write the information — suchas the station code, starting and ending date and time, time corrections, instrument orientation, dominant frequency
pass band, and magnification — by hand on a seismogram. To extract information from such data, researchers had tomeasure a seismogram’s parameters by hand. Interpretation relied on additional information (including station coordinates, instrument types, and operating organization) derived from the station operator or from standard sources suchas the National Earthquake Information Service (NEIS) Seismograph Station Codes and Coordinates (see Presgrave(1985)).

Standard for the Exchange of Earthquake Data - Reference Manual • 1

Chapter 1 • Introducing SEED
Seismologists have used digital recording methods since about 1970. While these methods have increased data quality,
they have also meant new challenges. Data exchange has been complicated by different data logger formats, by different
computer systems, and by incompatible exchange media. One cannot use, or even visually examine digital data without
extensive processing with additional computer hardware and software.
Many researchers collect digital earthquake data to perform computationally intensive waveform analyses. These
analyses require much more auxiliary information — information such as detailed instrument responses. This auxiliary
information is needed in computer-readable form and is sometimes distributed on the same electronic media as the raw
seismic data. Some institutions collect and distribute data in various formats, and whoever receives that data may haveto do substantial work to read it. Sometimes the required auxiliary information is incomplete or not even available incomputer-readable form.
Seismologists around the world are aware of these problems, and have recognized the need for a seismic data exchange
standard to solve them. Many have created exchange formats, but none has succeeded in creating a de facto standard.
In 1976, the International Deployment of Accelerometers (IDA) format was introduced. Perhaps because of its wide
distribution, the most successful format before SEED may be the United States Geological Survey (USGS), Global Digital
Seismograph Network (GDSN), Network-Day Tape format. This format became the only significantly used format within
the United States until 1987, when the Federation of Digital Seismographic Networks (FDSN) formally adopted SEED.
While the GDSN format has been adopted or emulated for some networks, it has not worked as an exchange standard
because: 1) the cost to reformat data for it is often too high, 2) it is too limited for other seismic applications because of its
orientation toward continuously-recorded global observatory data, and 3) it is not flexible enough to encompass changes inseismic instrumentation and computer media technologies.
In 1985, the International Association for Seismology and Physics of the Earth’s Interior (IASPEI), Commission on
Practice, formed a Working Group on Digital Data Exchange to propose a standard for international digital seismic dataexchange. Soon afterward, the FDSN formed and assumed the responsibility for developing an exchange format. At theirfirst meeting in August 1987, the Federation working group reviewed a number of existing formats — including SEED,a new format proposed as a starting point for discussion by the USGS for the working group. At a follow-up meeting in
December 1987, intensive discussion and numerous clarifications and modifications led to the new format’s adoption asa Federation draft standard. Other groups are also considering adopting SEED as their standard. We have prepared thismanual to help you discover SEED’s benefits.

A Description of SEED Format Versions
The SEED format is presently quite stable. During the first several years of its existence several changes were incorporated into the format. This section briefly summarizes the various versions of SEED and what the major changes andadditions are between the format versions.
Items that are new since the last SEED manual was published in Dec 1993 are labeled v2.4. Blockettes in versions 2.2, 2.3
or 2.4 are indicated in the blockette descriptions. Fields in blockettes in versions 2.2, 2.3 and 2.4 are identified to the leftof the box summarizing the field names for each blockette.

Version 2.0, February 25, 1988
The first officially released version of SEED was version 2.0. This version is documented by Halbert, Buland and Hutt
in a publication of the United States Geological Survey on February 25, 1988. The basic structure and philosophy of the
SEED format have not changed significantly from this first documentation of the format. The existence of the Volume,
Abbreviation, Station, and Time Span Control Headers were all defined at this time. The following paragraphs attempt toidentify the major changes in the SEED format in the later versions.

2 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 1 • Introducing SEED

Version 2.1, March, 1990
Version 2.1 was documented in an Incorporated Research Institutions for Seismology (IRIS) publication in March of
1990. The manual clarified many items in the SEED format as well as correcting mistakes in the previous manual.
Many of the new blockettes that were added were in the area of Response Abbreviation Dictionaries. The following
blockettes were added.
Blockette 8 - Telemetry Volume Control Header. This blockette was added to provide a mechanism whereby theVolume Control Headers did not have to be transmitted unless they had changed.

Blockette 44 - Response (Coefficients) Dictionary Blockette. Similar to Blockette 43 only for Blockette 54 information.
Blockette 45 - Response List Dictionary Blockette. Similar to Blockette 43 only for Blockette55 information.
Blockette 46 - Generic Response Dictionary Blockette. Similar to Blockette 43 only for Blockette 56 information.
Blockette 47 - Decimation Dictionary Blockette. Similar to Blockette 43 only for Blockette 57 information.
Blockette 48 - Channel Sensitivity/Gain Dictionary Blockette. Similar to Blockette 43 only for Blockette 58 information.
Blockette 57 - Decimation Blockette. This blockette was added to be able to completely specify instrument responsesof some of the newer data loggers. This blockette is now routinely used by several Data Centers of the FDSN.

Blockette 60 - Response Reference Blockette. This blockette was added so instrument responses in the response
abbreviation dictionaries could be referenced. This mechanism can greatly decrease the amount of overhead within a
SEED volume.

Blockette 74 - Time Series Index Blockette. This blockette essentially replaced blockette 73 in version 2.0. It provides
an index to all of the continuous time series on the SEED volume and is placed immediately before any data is placedon the volume. This allows one to quickly gain information about the time series in the volume by only referring to thefirst part of the SEED volume. In version 2.0 this information was intermingled with the data.

Version 2.2, August, 1991
The FDSN Working Group on Data Formats met again in conjunction with the IUGG meeting in Vienna, Austria. The
modifications to the SEED format were fairly minor at this meeting. A SEED reference manual was not published to
document changes in the SEED format but the minutes of the FDSN meeting in Vienna do provide documentation.
The following identifies the most significant changes that were new with SEED version 2.2.

Two new blockettes were adopted.
Standard for the Exchange of Earthquake Data - Reference Manual • 3

Chapter 1

Blockette 43 - Response (Poles and Zeros) Dictionary Blockette. This blockette was added so that poles and zeros
could be represented once and then referred to by the Response Reference Blockette. This blockette contains similar
information as blockette 53.

Chapter 1 • Introducing SEEDBlockette 61 - FIR Response Blockette. Blockettes (54) and (44) have traditionally been used to represent FIR filter
coefficients in the SEED format. These blockettes require that all coefficients are specified and that an error for eachcoefficient be given. In practice most FIR filters possess some symmetry properties and the error for the coefficients is not
used. For this reason blockette 61 was introduced so that the FIR filter specification would require less space.
Blockette 41 - FIR Dictionary Blockette. Blockette 41 is the abbreviation dictionary blockette that corresponds toblockette 61.
Dataless SEED Volumes. The FDSN also adopted the practice of generating dataless SEED volumes with SEED version
2.2. A dataless SEED volume contains the normal Volume, Abbreviation, and Station Control Headers but omits the Time
Span Control Headers and the data records. The purpose of these volumes is to provide an alternate method for making
sure that various Data Centers have current and correct information for seismic stations. This represents a turning point
in SEED exchange, in that metadata could now be handled separately from waveform data, recognizing the metadatachanges frequently, (for example the result of station maintenance, calibration, etc), in contrast to the waveform data,
which is relatively stable.

Version 2.3, December, 1992
The FDSN met in Seattle, Washington, USA in December of 1992. At that time SEED version 2.3 was adopted. Somenew blockettes were added and several additional fields were added to existing blockettes.
The following blockettes have been added with SEED version 2.3:
Blockette 42 – Response Polynomial Dictionary. Use this blockette to characterize the response of a non-linear sensor.
Blockette 62 – Response (Polynomial) Blockette. Use this blockette to characterize the response of a non-linear sensor.
The polynomial response blockette describes the output of an Earth sensor in fundamentally a different manner than theother response blockettes. The functional describing the sensor for the polynomial response blockette will have Earthunits while the independent variable of the function will be in volts. This is precisely opposite to the other response
blockettes. While it is a simple matter to convert a linear response to either form, the non-linear response (which we candescribe in the polynomial blockette) would require extensive curve fitting or polynomial inversion to convert from one
function to the other. Most data users are interested in knowing the sensor output in Earth units, and the polynomial
response blockette facilitates the access to Earth units for sensors with non-linear responses.
Blockette 100 - Sample Rate Blockette. At times the sample rates in blockette 52 and the fixed section of the data header
have proven to be inadequate to represent the sample rate to the desired precision. An optional blockette 100 was added toallow a floating point sample rate to be entered. If present, it overrides the sample rate in blockette 52 and the fixed sectionof the data header.
Blockette 1000 - Data Only (MiniSEED) Blockette. Data records by themselves do not contain enough information bythemselves to allow time series data to be plotted or even simply analyzed. With the addition of a small amount of additional information these limitations are removed. Blockette 1000 is the Data Only (MiniSEED) Blockette that will allow
SEED data records to be self-sufficient in terms of defining a time series.
Blockette 1001 – Data Extension Blockette.
Blockette 2000 – Variable Length Opaque Data Blockette.

4 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 1 • Introducing SEED
SEED allows for the modification of existing blockettes by appending new fields to the end of existing blockettes. Thisis always done in a fashion that maintains compatibility with older format versions. SEED readers that do not support
the newer version simply ignore the added fields. With SEED version 2.3, two of the existing blockettes were modified.
The following blockettes have been modified with SEED version 2.3.

Blockette 50 - Station Identifier Blockette. Field 16 was added to the Station Blockette to designate the Network
Code. This two letter code is assigned by the FDSN and must be present.
Blockette 71 - Hypocenter Information Blockette. Three fields were added to blockette 71. Field 12 now contains
the Flinn-Engdahl seismic region number. Field 13 was added to provide the Flinn-Engdahl seismic location number.
Field 14 was added to provide the Flinn-Engdahl standard geographic name.
Blockette 72 - Event Phases Blockette. Field 11 was added to the Event phases blockette to identify the source of thephase pick. It refers to abbreviation blockette 32. Field 12 was added to the Event Phases Blockette to designate the
Network Code of the station for this pick.
Blockette 74 - Time Series Index Blockette. Field 16 was added to designate the Network Code of the designated Time
Series.
Fixed Section of Data Header. Field 7 was previously defined as two reserved bytes. With SEED version 2.3 thesebytes have now been assigned as the Network Code.

Version 2.4, April, 2004
The following modification was introduced in version v2.4.
Fixed Section of Data Header. Field 2 is now defined as the data quality indicator, indicating level of data quality
control that has been applied.

Version 2.4, October, 2007
The following clarifications were introduced after the July 2007 FDSN meeting:
Fixed Section of Data Header. The header/quality indicator (field 2) can be “M” to indicate modified or merged datain addition to the “D”, “R”, and “Q” indicators.
Blockettes 54 - Response (Coefficients) Blockette and 61 - FIR Response Blockette. Added text to clarify that filter
coefficient order is forward order.
Blockette 57 - Decimation Blockette. Clarified the sign convention for the estimated stage delay (field 7) and correction applied (field 8) values.
Appendix A - Channel Naming. Added more band codes to cover very high and very low sampling rates.

Version 2.4, August, 2012
The folllowing clarification was introduced.
Blockette 62 - Response (Polynomial) Blockette. The usage of Blockette 62 has been refined for clarity and usefulness.

Standard for the Exchange of Earthquake Data - Reference Manual • 5

Chapter 1

Blockette 10 - Volume Identifier Blockette. Two fields were adopted at the end of Blockette10. Field 7 is the volume
time and provides the actual date and time that the volume was written. Field 8 provides a place to document the nameof the organization that wrote the SEED volume. An optional ninth field was added to this blockette that can be used tolabel a particular SEED volume.

Chapter 1 • Introducing SEED

What This Manual Covers
SEED’s design goals, implementation strategy, and recommended usage are the subjects of the remainder of this firstchapter. Chapter 2 provides an overview of SEED’s format structure, and introduces blockettes. Chapter 3 presents
some conventions — important information that you will need to use SEED effectively. Chapters 4 through 7 describe
the format standard for control headers. Chapter 8 details the data records. A series of appendices follow; each contains
information that may help you.

Figure 1: Sample Page
In preparing this manual, we wanted to specify the structure and organization of the format, as well as the placement,
value range, and coding of every defined parameter. While many readers may be interested in which parameters areincluded in the specification, how they are encoded, and how they are organized, we recognize that only a few readers
will find the details of the format immediately interesting. However, we wanted to document the format as completely as
possible so that you can learn about SEED’s features, use it, benefit from its usefulness — and evaluate it thoroughly.
At a Federation meeting held in Blanes, Spain, on June 19, 1988, the Federation working group adopted the SEED format
as an international standard for the exchange of Federation seismic data. Beginning on January 1, 1988, GDSN data
has been available in SEED format. The Data Management Center (DMC) at the Incorporated Research Institutionsfor Seismology (IRIS) has adopted SEED, and uses it as the principal format for its IRIS/DMC datasets. IRIS has also
developed a SEED reading program, named “rdseed”, to help researchers convert these datasets into trace formats
for which analysis tools already exist. By distributing this document now, we want to make the entire seismologicalcommunity aware of the format, and we want to solicit your comments.

6 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 1 • Introducing SEED

Acknowledgments
This manual represents the combined effort of many individuals within the Federation of Digital Seismographic
Networks (FDSN) and could not have been produced without the cooperation of its members. The SEED format wasreviewed and modified at a number of meetings from 1987 to 1992; the first was hosted by the USGS in Albuquerque,
New Mexico, December 3-4, 1987. The next meeting was the SEED Programmers’ Interest Group in Golden, Colorado,
December 14, 1988. May 10-11 of 1989 the Federation working group met in Baltimore, Maryland, where the SEED
format was further developed and significant support for the format was shown by both the United States and international attendees. The result of these efforts is evident in the first edition of the SEED Manual version 2.1.

Australian Geological Survey (AGS)
Geological Survey of Canada (GSC)
Geoscope
GERESS
German Regional Network
Harvard University
Grafenberg
Incorporated Research Institutions for Seismology (IRIS)MEDNETNORSAR
ORFEUS
PoseidonQuanterra, Inc.
University of California, San Diego
University of Texas
University of Washington
USGS/Albuquerque Seismic Lab
USNSNAustralia
CanadaFranceGermany
Germany
U.S.
Germany
U.S.
Italy
NorwayThe Netherlands
Japan
U.S.
U.S.
U.S.
U.S.
U.S.
U.S.

The SEED Format is maintained by FDSN Working Group 2 on Data Exchange. Its present members are listed on
http://www.fdsn.org.

Introduction to the Format
The SEED format can be used in successive steps, and accommodates data exchange spanning any temporal or spatial
domain. For example, the format is used to transfer data from a station processor to a data collection center, then to adata management center and, finally, to an end user. (The SEED databases may be augmented or modified at stages
along the way.) Additionally, data collection centers and data management centers are using features of the format forarchival storage and data retrieval, both in real-time and .delayed delivery, depending on data collection mechanisms.
Although SEED has evolved primarily for institutions that exchange data, seismologists have adopted other uses forthe format. Some seismic station processors generate SEED data in the field. This minimizes the collection anddistribution efforts required. Seismologists are also using the format to transmit seismic data by electronic means,enabling data ingestion and dissemination in real-time. Finally, researchers working with other ground based geophysical observations unrelated to earthquakes (e.g., strain, tilt, GPS, environmental sensors, gravimetric or magnetic
field data) find SEED suitable. In it’s most current implementation, the SEED format has essentially taken on two
forms: the miniSEED format utilized for waveform files, and the dataless SEED format, utilized for metadata files, withless emphasis put on the full SEED format, given that current Relational Database Management Systems (RDBMS’)
Standard for the Exchange of Earthquake Data - Reference Manual • 7

Chapter 1

After the publication of the first edition of the SEED Manual there was a meeting in August 1990 in Golden, Colorado
at which the SEED format underwent some modification. The next meeting was held in Vienna in August of 1991 at
which time more revisions were discussed to improve the SEED format. This resulted in Version 2.2. A meeting heldin Seattle, Washington, in December, 1992, led to the adoption of Version 2.3. A meeting was held in Hawaii, in April
2002, at which enhancements were made resulting in the present version of SEED 2.4. The following is a list of theinstitutions with representatives in attendance at one or more of the above mentioned meetings.

Chapter 1 • Introducing SEED
manage metadata and waveform data separately when collected, but the community still relies on fullSEED for data
distribution from data centers to end users, with an increasing use of distributing pure miniSEED combined with accessto dataless SEED volumes. There is a higher degree of efficiency, and allows for rapid re-distribution of metadata when
information changes.
The SEED format was not designed for use with non-time series data, nor with time series data sampled at unequalintervals in time (nevertheless, mechanisms for including console logs were easily accommodated). These types of data
are rare enough that complicating the format to include them does not seem worthwhile. We also did not design SEED
for the exchange of processed (e.g., filtered) data or synthetic data (i.e., created by computer modeling). While such use ispossible, we will not support it.

Design Goals and Strategies
The SEED format results from the design contributions of many seismologists and computer professionals. Their experience includes constructing other special seismic data distribution formats; in coordinating computer, operating system,
and mass storage device compatibilities, behaviors, and peculiarities across a wide range of manufacturers; and in working
with the International Standards Organization (ISO), American National Standards Institute (ANSI), and other industry
standards. The result: a format that can meet the needs of many individuals and institutions that collect, record, transmit,
and read seismological data.
The SEED format relies on a few assumptions that are common to all digital seismic data exchange formats currently inuse for network data. First, early computer architectures commonly used the 8-bit byte, so this became the de facto basis
for the format. Second, data from several sources — many field stations operating within a collective network, each containing different channels, recorded over a few discrete time spans — might make up a typical logical full SEED volume.
(Note that these assumptions do not prohibit less demanding uses, such as the recording of data from a single geophysicalobservatory.) Several logical volumes together could fit on a single physical volume. Each logical volume should begin
with auxiliary, or parametric, information organized into one or more control headers, followed by a stream of raw, timeseries data.
Based on those assumptions, the SEED designers applied their experience to create a format with certain goals in mind.
As they worked, they realized that they needed to implement certain strategies in order to reach those goals. They created
SEED to meet these criteria:

General. SEED works for continuous, station oriented and event oriented waveform data from single field stations,observatories, networks, or arrays. (SEED can also work with other geophysical time series data of potential seismological interest.) However, generality sufficient to support both station and event-oriented data requires considerable format
complexity.
Generality in defining important auxiliary information adds to this complexity. Because computers read SEED data, thiscomplexity requires a sophisticated data-reading program. Such reader software is available from IRIS and other sources.

Self-defining. The data from each channel includes all the needed information. This self-defining feature makes

automatic processing easier. A series of control headers defines the auxiliary information as global to the entire volume,
as well as specific to each channel. At a minimum, information about the volume, about station-channel characteristics,
and about the data’s time span appears in separate control headers that precede the time series data. Station control
headers include station location and channel response (transfer function) information. The time span control headers allow
for hypocenter and phase reading information. Additional auxiliary information, specific to a particular station-channel
at a particular time, is embedded in the data stream.

Robust. SEED data include enough embedded information to allow recovery from recording and transmission errors.

Logical records divide each volume. Each logical record begins with information on the record type and its absolutesequence within the volume. Logical control header records are encoded entirely in printable American Standard Codefor Information Interchange (ASCII) characters conforming to the ANSI standard. They are therefore directly readable
8 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 1 • Introducing SEED
by people, so control header records that have been damaged or incorrectly written can be interpreted. In addition,
each logical data record has header information embedded between the record identification information and the data.
This embedded information permits unambiguous identification of the data, should all the control headers be missing
or destroyed.

Efficient. SEED minimizes wasted space for storage and distribution. As digital seismic data become available in

Portable. The SEED format is suitable for easy and effective reading by any commercially available computer,using any commercially available operating system and any commercially available dismountable mass storage media.
At the time of this manual’s preparation, several SEED reading and writing programs exist for platforms by Digital
Equipment Corporation, Sun Microsystems, and some personal computers. Operating systems that work with SEED
now are SOLARIS, LINUX, Windows, OS X and other forms of UNIX are supported. Also, the lengths (in 8-bit
bytes) of SEED logical records are always a fixed power of two. This means efficient data storage and rapid random
access on the widest possible variety of computer equipment. Exchange volumes can have logical record sizes of 256
8-bit bytes or larger. Formatted data structures and unformatted data types are appropriately aligned, conforming tohigh-level computer language standards.

Computer readable. Humans do not usually read comment information associated with data, despite the apparent

advantages of including such comments. Nevertheless, a computer can extract a summary of relevant comment information for the user from SEED data. For example, the IRIS SEED reader software currently provides summary listingsof comments for station and channel data. The SEED control headers are coded in a computer readable hierarchy ofblockettes. These blockettes contain fixed and variable length data fields. The blockettes are self-identifying sequencesof data fields that assist computer readability, storage efficiency, and flexibility. Comment information is contained in abrief, computer readable form; the actual comment is defined in the abbreviation dictionary control header.
Referencing fields within blockettes relate important information. For example, fields 8 and 9 of blockette [52] refer toblockette [34]. For more information about cross-referencing fields, see Appendix F.

Figure 2: Blockettes with Cross-Referencing Fields

Computer usable. By not having to transcribe large amounts of information to prepare SEED data — an awkward

activity at best — fewer human errors are introduced. You do not have to use text-editing software because SEED
supports the automatic writing and reading of auxiliary data. You can write all parametric information using any
Standard for the Exchange of Earthquake Data - Reference Manual • 9

Chapter 1

increasing quantities, wasted space becomes too costly. SEED’s storage efficiency creates an additional benefit: you
can access the data with fewer input requests. SEED uses variable length and optional fields within the control headers
to conserve space. You can abbreviate lengthy, repeated ASCII data items: an abbreviation dictionary control header
defines those abbreviations. After the control headers, all subsequent data records (with embedded information) arecoded as binary, and can be variable in their total length. A system of indices (cross references) to logical records makefor efficient access: the volume header refers to the station-channel and time span headers; the time span headers referto the data records.

Chapter 1 • Introducing SEED
computer language for any computer. Since auxiliary information is binary and is embedded in the data records, you
cannot easily read or write it without a computer. This keeps data safe from accidental editing.

Flexible. SEED supports currently unforeseen future usage by including extensible auxiliary information with thetime series data. If desired, you can define new field digitization formats without modifying the format standard. Eachblockette and its trailing data fields are optional. Blockettes that are represented always identify themselves and measure
their lengths. This allows you to append new data fields to blockettes that are already defined (or new blockettes to be
defined), all without altering the existing control header structures in any way. This overcomes a significant failing ofother, older formats — a failing that quickly made them obsolete.

Self-correcting. Even though errors will find their way into distributed station-channel descriptive information(metadata) and other data, SEED provides a means of distributing corrections for preceding volumes within a subsequent
logical volume. You can distribute the corrected station control header, called the dataless SEED volume, flagging it tosupersede the previously distributed information that needs updating for a given effective time period. You can specify
that the correction information should apply to the new data on the same distribution volume, or not. If you do not want
the correction information to apply to that new data, just create more than one station control header for the same stationon the SEED volume — one for the older data, and one for the new data. You will also need more than one station control
header for the same station if station or channel characteristics were changed during the time span of the volume — forexample, after a maintenance site visit. (In this case, do not set the update flag.)Can store most field digitization formats. SEED efficiently uses field digitization and recording data word

formats. This is a benefit because separate conversions to other formats can be costly and may sacrifice precision or waste
storage space. Also, data logger problems may only be traceable in the original format — which is what SEED uses.
SEED’s data description language permits specifying any reasonable field digitization or recording data word format.
SEED reading programs convert it into binary data suitable for the reading computer. The abbreviation dictionary control
header abbreviates the ASCII data description string.

Can access any sequential or random access media. Although seismologists will continue toIuse sequential media such as magnetic tapes for the foreseeable future, SEED also supports more efficient data access on randomly
accessible media, such as magnetic and optical disks. SEED uses fixed length logical records. These allow efficient
random access on any media available to any computer. SEED provides indices to allow efficient random access of logicalrecords when available. And, for sequential media, these indices facilitate the use of skip rather than read operations.

Usable as a field recording format. SEED allows you to use a modified subset of the format for data recording

at a field station, but several constraints are imposed by the real-time nature of station processors. The entire time spancontrol header and some fields in the other control headers cannot be created because the relevant information will not be
available when the headers are written. Also, station processor memory constraints may require smaller logical records
and block multiplexing of data channels (each logical record contains data from one channel, but successive logical records
are interspersed with logical records from other channels). In addition, state-of-health, console log, and calibration information — of direct interest only to the institution collecting the data — can be included. Summaries of such data
may appear in appropriate station control header fields when the exchange volume is created. Finally, a special telemetry
volume format is available.

Efficient at merging data . Data collection and data management centers can merge data from several standard

format volumes onto a new volume, with minimal changes to the auxiliary information and with no changes to the logicalblock structure for the data and for most of the control headers. SEED supports different logical record sizes. However,to simplify the merging of volumes, the lengths (in bytes) of logical records will always be a power of two. This meansthat any logical record size is a multiple or sub-multiple of any other, ensuring compact storage and rapid access on mostcomputer devices. You can efficiently string together many smaller logical records into one larger logical record, withoutchanging any data item except the logical record identification information.

10 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 1 • Introducing SEED

Recommended Uses
Although the SEED format is flexible, we recommend limiting its use in some cases. As you use this format, keep thefollowing in mind:

Multiplexing. Whenever possible, de-multiplex all data. We discourage the multiplexing of data channels with acommon sample rate, and from one station, even though SEED supports it. The format can become very complicatedand convoluted, and data compression can become difficult when using multiplexing. We support block multiplexingof channels from one station for field tapes, but not for data exchange. SEED permits the multiplexing of array data if
absolutely necessary.

properly specified. Blockette 30: Read Appendix D carefully, paying attention to the section on Integer Format Family 0. Key 1 should specify the number of channels being multiplexed. Blockette 52: A blockette 52 should
be written for each multiplexed channel. Field 5 will specify which subchannel is being described. Sub channel
numbering starts with one.

Word order. SEED utilizes the Big Endian word order as its standard.
Logical record size. Each volume establishes a logical record size for itself. We strongly recommend a logicalrecord size of 4096 bytes for volumes created by data collection and data management centers. At the time of thiswriting (2005), logical record sizes in excess of 4096 bytes have not been written. Logical record sizes for data records
as small as 256 bytes are supported. While all logical records on a SEED volume are usually the same size, the format
can make exceptions for data records written in the field. We recommend using data records as large as 4096, andusing the variable size feature only when absolutely necessary — and then only after coordination with the appropriate
data collection center to ensure readable data. In practice, smaller record lengths are better for real-time data, as thisreduces latencies and time slewing across record boundaries.

Channel response. You can define each station-channel’s transfer function in a variety of ways. These include
a concatenation, or “cascade” of formal mathematical descriptions of analogue and digital filter sections, tables ofamplitude and phase, or simple approximations. At a minimum, give the most complete and mathematically correct
description of each station- channel transfer function available. In addition, you can give alternate descriptions that
may have more intuitive appeal.

Hypocenters and phase data. For event oriented data, you can assume that the phase arrival times or readings

given in a time span control header are associated with the hypocenter(s) given in that same control header. For station
oriented data, the hypocenters are optional and may be taken from a catalog. The readings are also optional, and they
may be unassociated estimates made automatically in the field by the station processors. In either case, the readings
refer to positions in the time series data that immediately follow.

Dataless SEED Volumes. It is legal to produce a SEED volume that contains only header information and nodata. This has proven to be an expedient way for various data centers to insure that they have current information fromvarious networks. In this case one would include volume, abbreviation and station control header but omit time spancontrol headers and data records.

Dataonly SEED Volumes. Just as the SEED format encompasses Dataless SEED volumes, it also defines the useof Dataonly or MiniSEED volumes. Dataonly SEED volumes contain only SEED data records and blockettes in data
records as defined in this manual (see Appendix G). For operators that feel sure that they know station characteristics
and do not need to repeatedly transmit SEED volume control header information, Dataonly SEED volumes are the appropriate method of data transfer. Other than fixed section of data header information, these volumes contain nothing
but time series. In fact this subset of SEED looks very similar to other trace analysis formats. The MiniSEED blockette(blockette 1000) is required so that the information is self-defining.
Standard for the Exchange of Earthquake Data - Reference Manual • 11

Chapter 1

Special Considerations for Multiplexed Data in Data Records. The following blockettes must beChapter 1 • Introducing SEED

Console logs. Data written at a field station may include console logs. The log information appears as a separate

data channel with the appropriate data family code. Printable ASCII, standard forms control characters, and otherspecial characters such as the ASCII bell (BEL) are acceptable. Alternate character sets (such as Kanji) are acceptable
for languages that do not use the U.S. ASCII character set. We suggest formatting console log information in a way that
permits automatic parsing at a data collection center — reducing manual labor and human error. These same comments
apply to nominal data such as telemetry flag status words, or door opened/closed flags, except that this information should
appear as if it were an equally sampled time series.

Conventions
In addition to the recommended uses described above, SEED supports the following features:End-of-file marks. Occasionally, some types of media need end-of-file marks added to the data stream (or they may

be convenient for some purpose beyond the scope of normal SEED usage). SEED makes no use of single end-of-file marks
and will ignore any present. The logical record sequence numbers must continue to increment after the embedded end-offile mark. SEEDIinterprets multiple end-of-file marks in sequence as the end-of-information for the physical volume. We
require four end-of-file marks in sequence at the end of physical magnetic tape volumes to ensure that the reading programunambiguously interprets that point as the end of the volume.

Noise records. SEED writing programs can write blank or noise records at any time; SEED readers ignore suchrecords. (These records are typically used to avoid a bad place on magnetic tape.) Use a correct logical record sequencenumber, ensure that the noise record has the correct logical record length, and set the remainder of the record (particularly
the record type code) to spaces (ASCII 32). Noise records are particularly useful for field recording and for the starting
points of 9-track magnetic tapes that have been used before.

Blank fields. Verify that all auxiliary information is as complete and correct as possible. If the current value of aparticular field is not available, leave the field blank or set it to zero, as appropriate.

Field recording termination. Flush all data buffers before terminating a local field station recording. This ensuresthat data records for all channels will begin at about the same time on the following physical volume.

Header flushing. Sometimes it is useful to flush all data buffers and repeat all control header information periodically(e.g., each day at midnight). When flushing buffers, continue data recording after the repeated control headers. This
strategy guarantees that low data rate channels are saved periodically and synchronizes the start times of data records
for all channels. Control headers should contain current information if it has changed since the beginning of the volume.
SEED supports, but does not require, header flushing as needed. Flush headers that have changed as a result of a site
maintenance visit as soon as possible after making the change. SEED requires this, but only for the control headers thathave changed.

Calibration. When performing calibration, testing, or repairs, field stations should always flag that maintenance operations are in progress. This notifies data collection personnel and end users of potential difficulties with the data fromthose field stations at those times.

Standards. Wherever practical, the SEED format follows existing internationally agreed-upon standards. SEED codes

all character data according to the ANSI standard ASCII format (we recommend using uppercase alphabetic characterswhenever possible). Where possible, we try to give physical units for transfer functions in uppercase SI units (Le SystèmeInternational d’Unités, the international standard metric system). SEED uses other de facto standards such as 8-bit bytes
and the two’s complement binary integer data word format.
12 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 2

Chapter 2

An Overview of SEED

Format Organization
Because the SEED format was designed to achieve many goals, it may appear complex or formidable at first. Actually,
its structure is straightforward. This section demonstrates that by outlining its organization. In this outline, we use
a number of specialized terms. These terms have specific meanings for the SEED format; they are defined in theglossary at the end of this manual. Also, Appendix E shows some sample data in logical volumes; refer to it for typicalexamples. Keep in mind that only a subset of SEED would be used for any given application.

A complete and internally consistent implementation of the SEED format results in one logical volume. Depending on
the media type, you can distribute one or more logical volumes on one physical volume. You may not, however, createa logical volume that spans more than one physical volume.

Standard for the Exchange of Earthquake Data - Reference Manual • 13

Chapter 2 • An Overview of SEED

Figure 3: Logical Volume Organization Within a Physical Volume

Physical and Logical Volumes
At the highest level of organization (a physical volume), the SEED format consists of one or more logical volumes, one
after another. In addition, some randomly accessible media require placing a device-dependent control header at the startof each physical volume to access the associated logical volumes. (This physical header is external to SEED. Reading
and writing software does not have to manage these headers — the computer’s media-accessing software must take careof that.)Three types of logical volumes are possible: field station-, station network-, and event network- oriented. The structure ofeach logical volume is the same, but the interpretation of some data fields, particularly for hypocenters and phase arrival
times, will be different.

Format Objects
Both station network and event network volumes contain sequences of format objects — complete and internally consistent collections of related information that describe some aspect of the data on the volume. Two format objects are used:• control headers (formatted in ASCII) that contain auxiliary information about the volume, the station-channels, andthe data• time series (binary, unformatted) that contain raw data and embedded auxiliary information that is channel specificand time dependent

Control Headers
Four control headers are defined:

14 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 2 • An Overview SEED• volume index control headers: These contain information about the time of the data, logical record length, andformat version of the logical volume, as well as indices to the station and time span control headers. The indices help
retrieve data quickly.
•
abbreviation dictionary control headers: These contain the definitions of abbreviations used in other control
headers. Abbreviation dictionaries are referred to by 1) other abbreviation dictionary entries, 2) blockette [400] in thetime series format objects, 3) station identifier blockettes [50] and [51], and 4) channel identifier blockettes [52] through[59] (see Appendix F).

• station control headers: These provide relevant operating characteristics for a station and all of its channels —including station location, instrument types, and channel transfer functions. At least one station control header must
exist for each station. The station control headers permitted on a volume are those that pertain to the stations on thatvolume.
• time span control headers: These identify the time span within which the time series that follow were recorded.
They also provide indices to each time series, as well as information about the seismic events that may have occurred
during the time interval. One volume may contain many time spans.

Standard for the Exchange of Earthquake Data - Reference Manual • 15

Chapter 2

Space is saved by making abbreviations for lengthy comments and field data format definitions. Other abbreviations
are used to facilitate automatic processing and to guarantee coding consistency, particularly for units fields. (Note:
The abbreviations, if used, are not optional; the fields that need them defined have no room themselves for their definitions.)

Chapter 2 • An Overview of SEED

Figure 4: Format Object Organization Within a Logical Volume
SEED divides each format object into one or more fixed length logical records. Each logical record begins with a logicalrecord identification block, and usually contains one or more fixed length physical records. However, it is possible topack several logical records into one physical record — for example, the Albuquerque Seismological Laboratory (ASL)
packs eight 4096- byte logical records into each 32768-byte physical record to minimize record mark overhead (we do notrecommend this practice for random access media). Different storage devices use physical records of different lengths,
but this does not affect SEED users.
Version 2.1 requires that SEED writing programs move the time span headers together to a position immediately following
the station control headers. Version 2.0 required that data for a time span be written after its associated time span header,resulting in time span headers being interspersed with their time data. SEED reading programs should support bothformat object organizations, but SEED writing programs should only write according to the version 2.1 organization.

Blockettes
Each control header is made up of a sequence of blockettes — data structures that contain a type identifier, length, andsequence of data fields specific to the blockette type. Blockettes may be either ASCII formatted (in control headers) or
unformatted binary (in data records). Each data field contains auxiliary information on one topic, and may be either fixedor variable in length. Most blockettes are optional.
16 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 2 • An Overview SEED

Chapter 2

Figure 5: Organization of Control Headers

Figure 6: Organization of a Blockette
Control headers are coded entirely in printable ASCII characters, and they contain no data records. In contrast, timeseries objects are binary (not ASCII-formatted), and are subdivided into data records, each with a data record identification block.

Standard for the Exchange of Earthquake Data - Reference Manual • 17

Chapter 2 • An Overview of SEED

Data Records
A physical record may contain one or more logical records, which in turn may contain one or more data records. The
SEED structure allows conversion from one logical record size to another without having to reformat data records —provided that the data record’s size is smaller than the new logical record. Each data record contains a fixed header
section, a variable header section, and a data section.

Figure 7: Record Organization Within a Time Series Format Object
The fixed header section provides the minimal self definition needed to use any portion of the data without any otherauxiliary information. A sequence of unformatted blockettes, each of which is optional, make up the variable header
section. These blockettes provide information about channel specific, time dependent events such as automatically determined phase arrival information or a calibration in progress. The data section contains the actual time series data.

18 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 2 • An Overview SEED

Chapter 2

Figure 8: Organization of Data Records

How to Write SEED Data
The following two algorithms are written in Pascal-like pseudo code. They show the order in which data must be
written to a SEED volume. The first algorithm describes a field station volume; the second outlines the station andevent oriented network volumes. We also include a section describing electronic data transmission and telemetry
volumes.

Procedure to Write Field Station Volumes
Procedure

Blockette

begin
Start_Volume_Header_Records();
Write_Volume_ID_Blockette_5();
Flush_Any_Remaining_Volume_Header_Records();[5]

Standard for the Exchange of Earthquake Data - Reference Manual • 19

Chapter 2 • An Overview of SEED
Start_Abbreviation_Dictionary_Header_Records( );for each_data_format_type do
Write_Data_Format_Dictionary_Blockette_30();[30]

Start_Generic_Abbreviation_Header_Records ();for each_abbreviation do
Write_Generic_Abbreviation_Blockette_33();[33]

Start_Units_Header_Records ();for each_unit doWrite_Unit_Blockette_34();[34]

Flush_Any_Remaining_Dictionary_Header_Records ();Start_FIR_Dictionary_Records ();for each_dictionary do
Write_Dictionary_Blockette_41();[41]

Start_Poles & Zeros_Dictionary_Records ();for each_poles & zeros do
Write_Response_(Poles & Zeros)_Dictionry_Blockette_43();[43]

Start_Coefficients_Dictionary_Records ();for each_coefficient do
Write_Coefficient_Dictionary_Blockette_44();[44]

Start_List _Dictionary_Records ();for each_list do
Write_Response_List_Dictionary_Blockette_45();[45]

Start_Generic_Response_Dictionary_Records ();for each_generic_response do
Write_Generic_Response_Dictionary_Blockette_46();[46]

Start_Decimation_Records();
for each_decimation do
Write_Decimation_Dictionary_Blockette_47();[47]

Start_Channel_Sensitivity/Gain_Dictionary_Records();
for each_channel_sensitivity do
Write_Channel_Sensitivity/Gain_Dictionary_Blockette_48();[48]

for each_station do begin
Start_Station_Header_Records ();Write_Station_ID_Blockette_50();for each_station_comment do
Write_Station_Comment_Blockette_51();for each_channel do begin
Write_Channel_ID_Blockette_52();
for each_stage do begin
if poles_and_zeros thenWrite_Response_Blockette_53();
or Write_Response_Blockette_60();
if coefficients then
20 • Standard for the Exchange of Earthquake Data - Reference Manual

[50]
[51]
[52]
[53]
[60]

Chapter 2 • An Overview SEED
Write_Response_Blockette_54();
or Write_Response_Blockette_61();or Write_Response_Blockette_60();
if decimation thenWrite_Decimation_Blockette_57();
or Write_Response_Blockette_60();
if gain thenWrite_Gain_Blockette_58();
or Write_Response_Blockette_60();

end

end
Flush_Any_Remaining_Station_Header_Records ();Beginuntil end_of_media or operator_abort do begin
if station_change or channel_change do begin
Start_Station_Header_Records();
Write_Station_ID_Blockette_50();for each_changed_channel do begin
Write_Channel_ID_Blockette_52();
for each_stage do begin
if poles_and_zeros_changed thenWrite_Response_Blockette_53();
or Write_Response_Blockette_60();
if coefficients_changed thenWrite_Response_Blockette_54();
or Write_Response_Blockette_60();
if decimation_changed thenWrite_Decimation_Blockette_57();
or Write_Response_Blockette_60();
if gain_changed thenWrite_Gain_Blockette_58();
or Write_Response_Blockette_60();end {each_stage}
if FIR_Response_changed thenWrite_FIR Response_Blockette_61();or Write_Response_Blockette_60();end {each_changed_channel}
Flush_Any_Remaining_Station_Header_Records();
end

end

end

[57]
[60]
[58]
[60]
[58]
[60]
[59]

[50]
[52]
[53]
[60]
[54]
[60]
[57]
[60]
[58]
[60]

[61]
[60]

if data_record_ready_to_write do
Write_Data_Records();

Standard for the Exchange of Earthquake Data - Reference Manual • 21

Chapter 2

end
if final_sensitivity thenWrite_Sensitivity_Blockette_58();
or Write_Response_Blockette_60();
for each_channel_comment do
Write_Channel_Comment_Blockette_59();

[54]
[61]
[60]

Chapter 2 • An Overview of SEED

Procedure to Write Station and Event Oriented Network Volumes
Blockette

Procedure
Begin
Start_Volume_Header_Records();
Write_Volume_ID_Blockette_10();
Write_Station_Index_Blockette_11();
Write_Time_Span_Index_Blockette_12();
Flush_Any_Remaining_Volume_Header_Records();

[10]
[11]
[12]

Start_Abbreviation_Dictionary_Header_Records();
for each_data_format_type do
Write_Data_Format_Dictionary_Blockette_30();[30]

Start_Comment_Dictionary_Header_Records();
for each_comment_type do
Write_Comment_Dictionary_Blockette_31();[31]

if event_volume then begin
Start_Cited_Source_Dictionary_Header_Records();
for each_cited_source do
Write_Cited_Source_Dictionary_Blockette_32();
end

[32]

Start_Generic_Abbreviation_Header_Records();
for each_abbreviation do
Write_Generic_Abbreviation_Blockette_33();[33]

Start_Units_Header_Records();
for each_unit doWrite_Unit_Blockette_34();
Flush_Any_Remaining_Dictionary_Header_Records();[34]

Start_FIR_Dictionary_Records();
for each_dictionary do
Write_Dictionary_Blockette_41();[41]

Start_Poles & Zeros_Dictionary_Records();
for each_poles & zeros do

Write_Response_(Poles & Zeros)_Dictionry_Blockette_43();[43]

Start_Coefficients_Dictionary_Records();
for each_coefficient do
Write_Coefficient_Dictionary_Blockette_44();[44]

Start_List _Dictionary_Records();
for each_list do
Write_Response_List_Dictionary_Blockette_45();[45]

Start_Generic_Response_Dictionary_Records();
for each_generic_response do
22 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 2 • An Overview SEED
Write_Generic_Response_Dictionary_Blockette_46();
Start_Decimation_Records();
for each_decimation do
Write_Decimation_Dictionary_Blockette_47();for each_time_span do begin
Start_Time_Span_Header_Records();
Write_Time_Span_ID_Blockette_70();
if event_network_volume then begin
Write_Hypocenter_Info_Blockette_71();
for each_Hypocenter do

[47]

[48]

[50]
[51]
[52]
[53]
[60]
[54
[61]
[60]
[55]
[60]
[56]
[60]
[57]
[60]
[58]
[60]
[58]
[60]
[59]

[70]
[71]

Standard for the Exchange of Earthquake Data - Reference Manual • 23

Chapter 2

Start_Channel_Sensitivity/Gain_Dictionary_Records();
for each_channel_sensitivity do
Write_Channel_Sensitivity/Gain_Dictionary_Blockette_48();for each_station do begin
Start_Station_Header_Records();
for original_and_any_updates do
Write_Station_ID_Blockette_50();for each_station_comment do
Write_Station_Comment_Blockette_51();for each_channel do begin
for original_channel_and_any_updates do begin
Write_Channel_ID_Blockette_52();
for each_stage do begin
if poles_and_zeros thenWrite_Response_Blockette_53();
or Write_Response_Blockette_60();
if coefficients thenWrite_Response_Blockette_54();
or Write_Response_Blockette_61();or Write_Response_Blockette_60();
if response_list thenWrite_Response_List_Blockette_55();
or Write_Response_Blockette_60();
if generic_response thenWrite_Generic_Response_Blockette_56();
or Write_Response_Blockette_60();
if decimation thenWrite_Decimation_Blockette_57();
or Write_Response_Blockette_60();
if individual_sensitivity thenWrite_Sensitivity_Blockette_58();
or Write_Response_Blockette_60();end {each_stage}if final_sensitivity thenWrite_Sensitivity_Blockette_58();
or Write_Response_Blockette_60();end {original_channel_and_any_updates}for each_channel_comment do
Write_Channel_Comment_Blockette_59();
end
Flush_Any_Remaining_Station_Header_Records();
end

[46]

Chapter 2 • An Overview of SEED

end

for each_station dofor each_channel dofor each_phase do
Write_Event_Phases_Blockette_72();end {each_time_span}for each_station dofor each_channel doWrite_Time_Series_Index_Blockette_74();
Flush_Remaining_Time_Span_Header_Records();
end
for each_station dofor each_channel dofor data_record_for_channel doWrite_Data_Records();
end

[72]

[74]

Field Station Volumes
Field station recordings use only a small portion of the SEED format: only a few brief control headers near the beginningof the volume, and no indices. Data are usually written to a field tape, and for only one station. In other cases — arraysof several stations, for example — headers written at the beginning of the volume describe all the stations and data format
types. The software should write data as buffers are filled, and complete volumes as they approach the physical end of themedia, or as operations personnel terminate them.
The Field Volume Identifier Blockette [5] should always appear in the Volume Index Control Header at the beginning ofeach volume. The Abbreviation Dictionary Control Header follows. Include a Data Format Dictionary Blockette [30] foreach data format used (usually only one or two). Write Generic Abbreviation Blockettes [33] for each abbreviation used in
the various station and channel blockettes, and Units Abbreviation Blockettes [34] for units used.
When writing data from multiple stations, flush out the previous logical record before starting to write the station control
header, so that the station control header will start on a new record. Start the station record with the Station Identifier
Blockette [50]. (Station comments may be included in Station Comment Blockettes [51].) Follow this with the informationfor each channel. Each channel should appear as a Channel Identifier Blockette [52], followed by the channel response.
Use any of the following blockettes that apply to a particular response configuration to describe it exactly as it would
appear on a network volume:•

Response (Poles & Zeros) Blockettes [53]•Response (Coefficients) Blockettes [54]•Decimation Blockettes [57]•Channel Sensitivity/Gain Blockettes [58]

Write a channel blockette and a set of response blockettes for each channel. (See Appendix C for more information.) To
ensure that valid and accurate station identification information is available, write it every few days, or when restarting
the station processor. Write new station identification information if the station configuration changes in the middle ofa volume — for example, after operator action or maintenance activity (which can also happen via remote access). The
Volume Index Control Header may appear multiple times on the volume, each time delineating a new sub-volume.
24 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 2 • An Overview SEED
After writing the station control header(s), start recording station data. Mix — i.e., block multiplex — channels in
any way (there are no restrictions on timing or spacing between channels), but keep the data for each channel in time
sequence.
For digital tape, write several tape marks (at least four) to the volume when the station operator wants to terminate thevolume, or when the end of the volume nears. Doing this tells the data collection center that any subsequent data does
not belong with this volume, but may be from an older, recycled volume. If the reporting station “crashes” and does not
successfully write EOFs (end- of-file marks) to the volume, the data collection center may have to examine the times,
and possibly the station identification information, to determine the end of the current data.

The field station volume control headers are similar to those of a station oriented network volume, with these exceptions:• some fields in the volume index control header (the volume ending date and time, and the indices to other control
headers) are not known when writing the header•

the station control header information may be incomplete•no time span control headers are present because the necessary information is not available•

small data record lengths may be used and different channels may use different data record lengths•

the data records are block multiplexed for all of the channels

Standard for the Exchange of Earthquake Data - Reference Manual • 25

Chapter 2

When terminating a volume, flush all data buffers — prematurely, if necessary — to the volume. This will keep data
(especially very long period data) from accumulating in a buffer for several days, then showing up later on subsequent
volumes. While you can place single EOFs anywhere within the SEED format for any reason, multiple EOFs must only
appear at the final end of the data.

Chapter 2 • An Overview of SEED

Figure 9: Organization of a Field Station Volume
If desired, control headers may be flushed periodically to form a sequence of logical sub- volumes within the field station
volume (see the Glossary for definitions). For a station network volume, there is only one data record per logical record.
When field station volumes are combined into a network, data records must be collected to satisfy the standard. SEED
allows you to concatenate several data records into one logical record to minimize computer resources required to solve
this problem.

26 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 2 • An Overview SEED

Merging Field Station Volumes into Network Volumes
Field station volumes differ from station network volumes. In particular, time span and indexing information areunavailable to the station processor, as may some station channel information. Logical records may be different sizesfor different channels, but only one size in a given volume for each channel. Data records for different channels will beblock multiplexed.
Merge station volumes into network volumes by:adding missing auxiliary information•

block de-multiplexing•

concatenating data records to make logical records of the required fixed size•

calculating time span information•

calculating indexing information•

creating time span control headers

If the missing auxiliary information is available on-line at the data collection center, complete this entire process automatically. Just compile a table of data record sizes and locations for each station channel while transcribing the station
volume from the field recording media onto temporary disk storage. Then, in a second pass through the data, reformat
the station volume as a network volume. With enough available random access storage, you can apply this process toa number of station volumes simultaneously, and produce a merged network volume. Although this procedure requires
substantial amounts of random access storage (which is generally quite inexpensive), it minimizes processor and input/
output time.
Also, remember that station oriented network volumes use time span control headers differently than do event oriented
network volumes: for station oriented volumes there will be one time span until the sub-volume ends, or the control
header changes; for event oriented volumes, there will be one time span per event (unless the events overlap).

Telemetry Volumes and Electronic Data Transmission
A special volume format — called the telemetry volume format — lets a data transmitter assume that the data receiver
has the most up-to-date control header information, unless otherwise requested. This means that, in many cases, only
the data and minimal control header information need to be transmitted; if the receiver needs more control headers,
the transmitter can send them, too. This procedure is not mandatory, but it can significantly reduce overhead on theavailable communications bandwidth. The pseudo-code and complete protocol for telemetry volumes have not yet
been designed.
Electronically transmitting digital seismic data is becoming increasingly important as the need for near-real-time
seismic monitoring grows. Electronic computer links can emulate sequential storage media to provide transparent
physical blocking of data as well as error detection, correction, and retransmission. Such links are exceptional onlyin their relatively low data rate and, in some cases, support for ASCII data only. The SEED data record format, as
defined for storage media, is already compact, minimally self defining, and reasonably robust. Also, SEED provides a
special Telemetry Blockette [8], allowing data transmission of only the newest data— as long as the receiver does not
specifically request a retransmission of previously transmitted control header information. Therefore, we recommend
Standard for the Exchange of Earthquake Data - Reference Manual • 27

Chapter 2•

Chapter 2 • An Overview of SEED
no modification of the data record structure for electronic transmission, with the possible exception of using smaller block
sizes if communication link reliability requires it.
If the link only supports ASCII data, then the transmitter and the receiver respectively will require binary-to-ASCII andASCII-to-binary protocol translators. Translators (such as Kermit) are widely available. With a continuously connected
link (as a permanent virtual circuit), you can transmit all ASCII header information periodically (e.g., data center to data
center). Or the transmitter may omit it and the receiver may add it (e.g., field station to data center).
If the link is established temporarily, the interactive session may begin by displaying the revision dates of all control
headers. The caller may then request the transmission of those control headers that have been updated since the caller’s
previous call. Note that software external to the SEED format will handle the interactive session, interactive control
header transmission, and protocol conversion — no modifications to SEED are required.

Software
Computer- and operating system-independent software in FORTRAN for reading SEED data is available. So are VMS(Digital Equipment Corporation) and UNIX (Bell Laboratories) versions of the reading program, in FORTRAN 77 and C,
respectively; and VMS software in C for writing data into the SEED format. The Albuquerque Seismological Laboratoryof the USGS can provide the VMS specific C language writing programs. The National Earthquake Information Centerof the USGS will provide the portable and VMS specific FORTRAN reading programs. IRIS supports and distributes
a C language reading program, RDSEED that can convert SEED formatted data into a format suitable for analysis anddisplay. IRIS also supports and distributes SEED writing software called POD, Program to Output Data. Contact theseorganizations for more information.

28 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 3

Chapter 3

SEED Conventions

ASCII Header Field Conventions
SEED uses four types of control headers: volume identifier headers, abbreviation dictionary headers, station headers,
and time span headers. (SEED also uses data record headers; these are described later in this manual.) Each header
makes use of one or more blockettes — individual “portions” of information that are header-specific, and that conformto the organization rules of their volume type. Some blockettes vary in length, and can be longer than the logicalrecord length.

Figure 10: Beginning Fields of a Control Header
Standard for the Exchange of Earthquake Data - Reference Manual • 29

Chapter 3 • SEED Conventions
Unlike data records with primarily binary data fields, data fields in control headers are not stored as binary values, but areformatted in ASCII.
We provide four categories of information for the fields within each control header blockette listed in this reference
manual:•field name•field type•field length•masks and flags

A field’s contents are usually described by a field name — for example, “Station call letters”
is the third field of the Station Identifier Blockette [50].
A field’s type describes how the field formats its data:
A — Alphanumeric ASCII string (fixed length)
D — Decimal integer or fixed point decimal number
F — Floating point number with an exponent
V — Variable length ASCII string, ending with a tilde: ~ (ASCII 126)
The length equals the exact number of characters in the field. Variable field length is described as a range (a—b), where ais the minimum number of characters, and b is the maximum. Some variable length fields have no fixed maximum length.
Character counts for variable length fields do not include the tilde terminator. The next field starts immediately after theend of the current field, or after the tilde for variable length fields. Always use the tilde to terminate variable length fields,
even if they are zero length.
Masks show how to place data in the space provided. Most computer languages provide some method for creating thesefields. Here are some examples of acceptable data for each mask, where the “Δ” denotes a single space (ASCII 32):
Mask“####”

Data Type
Unsigned integer

Example“0023”or “ΔΔ23”

30 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 3 • SEED Conventions
Signed integer“00023”or “Δ0023”
or “ΔΔΔ23”or “+0023”
or “-0023”
or “-ΔΔ23”or “ΔΔ-23”
or “ΔΔ+23”“####.####”

Unsigned fixed point“0003.1416”
or “ΔΔΔ3.1416”
or “ΔΔ23.0000”
or “ΔΔΔΔ.0200”“-###.####”

Signed fixed point“-003.1416”
or “ΔΔ-3.1416”
or “ΔΔ23.0000”
or “-ΔΔΔ.0200”

Leading spaces or leading zeros are allowed before the number, to the left of the decimal point. Null values (binaryzero) cannot be used as a substitute for spaces (binary 32 decimal). All unused places to the right of the decimal point
must contain zeros. Signs can be minus or plus, and can float to the beginning of the first digit. A zero or space can fill
the sign position. No sign specified implies a positive number.
The floating point mask behaves as described above, except that it contains the “E” exponential notation, and has
another sign for the exponent.
Mask“-#.####E-##”

Data Type
Signed Exponential

Example“Δ3.1416E000”
or “Δ3.1416EΔ00”
or “03.1416e+00”
or “-1.0000e-02”

Use a special mask, shown as TIME, for the ASCII date and time. The time field works like a variable length field,
described above. Truncate the time at the most significant valid time; leave off unneeded or unavailable time precision.
A few situations use an optional time field; in such cases the field appears empty, with just the tilde terminator. Arrange
the data inside as “YYYY,DDD,HH:MM:SS.FFFF” and use these subfields:
Mask
subfield

What it means

YYYY
DDD
HH
MM
SS
FFFF

The year with the century (e.g., 1987)
The julian day of the year (January 1 is 001)
The hour of the day UTC (00—23)
The minute of the day (00—59)
The seconds (00—60; use 60 only to note leap seconds)
The fraction of a second (to .0001 seconds resolution)

All positions of a time field must be zero padded to the left, but they do not need padding to the right if the time will betruncated. “1987,023,04:23:05.1” and “1987,023” are correct.

Standard for the Exchange of Earthquake Data - Reference Manual • 31

Chapter 3“-####”

Chapter 3 • SEED Conventions
Flags determine what ASCII characters can be placed in an alphanumeric or a variable length field:
Flag value

Permitted characters

U
L
N
P
S
_

Upper case A—Z
Lower case a—z
Digits 0—9
Any punctuation characters (including “_”)Spaces between words
Underline symbol

Variable length fields cannot have leading or trailing spaces. Leave fixed length alphanumeric fields left justified (noleading spaces), and pad them with spaces (after the field’s contents).

How to Assemble Control Headers
When assembling a header, first write an identifier block — the incrementing sequence number in the record, then therecord type code, followed by the continuation code — for a total of eight bytes. (New control headers use blank (Δ, or
ASCII 32) continuation codes; continuing records use an asterisk (*, or ASCII 42).)
Field nameType

Length

Mask or Flags

Sequence number (first record is 1)

D6“######”

Control header type code
V — Volume header
A — Dictionary header
S — Station header
T — Time Span header

A

1

Record continuation code
* — if continued from last record
Δ — if not continuedA

1

Next, write out the blockettes needed in the control header (you can write several blockettes, one after another, all under
one identifier block). For each blockette, write the blockette type in the record and then the total blockette length —including the seven bytes for the blockette type and length. Finally, write the entire blockette (or as much of it as will fit
in the logical record).
Field nameType

Length

Mask or Flags

Blockette type

D

3

“###”

Blockette lengthD4“####”

Blockette data

(see subsequent chapters)

If the blockette fits, then start the next blockette at the byte immediately following the end of the last. If the blockette does
not fit, assemble a new record, increment the sequence number, and set the continuation code to an asterisk. The record
then resumes on the byte after the continuation code. If you must write a record when it is not full (to begin a record ofanother type, for example), fill the remainder of the record after the last blockette with spaces. Then flush (write out) therecord. If there are less than seven bytes remaining, the record must be flushed. Never split a blockette’s “length/blockettetype” section across records.
32 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 3 • SEED Conventions

How Binary Data Fields are Described in This Manual
Throughout this manual, we use some conventions to describe the sizes of fields in the SEED format. Here are thebinary data types used in data record contents:

Number of bits

Field description

UBYTE
IBYTE
UWORD
WORD
ULONG
LONG
CHAR * n

8
8
16
16
32
32
n*8

FLOAT

32

Unsigned quantity
Two’s complement signed quantity
Unsigned quantity
Two’s complement signed quantity
Unsigned quantity
Two’s complement signed quantity
n characters, each 8 bits and each with a 7-bit ASCII character(high bit always 0)
IEEE Floating point number

The IEEE floating point format consists of three stored components: a sign (+ or -), an exponent, and a fraction. In thefollowing description of the storage format these notations will be used.
s = sign

e = biased exponent

f = fraction

The sign is the sign of the fraction. Rather than storing the sign of the exponent a bias is added to the exponent, and thebiased exponent is stored.

bit positions

s
31

e
30:23

f
22:0

IEEE single precision values occupy one 32 bit word as shown above in 68000 byte order. Bits 0:22 store the 23 bit
fraction, bits 23:30 store the 8 bit exponent, and the high order bit 31 stores the sign bit. The 23 bit fraction combinedwith the implicit leading bit provide 24 bits of precision in normalized numbers. The value of an IEEE single precision
floating point number is calculated as-1s x 2(e-127) x 1.f
The byte order of a FLOAT is specified in the station identifier blockette [50].
Binary data types are used in the BTIME structure:
Field type

Number of bits

Field description

UWORD
UWORD
UBYTE
UBYTE
UBYTE
UBYTE
UWORD

16
16
8
8
8
8
16

Year (e.g., 1987)
Day of Year (Jan 1 is 1)
Hours of day (0—23)
Minutes of day (0—59)
Seconds of day (0—59, 60 for leap seconds)
Unused for data (required for alignment).0001 seconds (0—9999)

NOTE: The BTIME structure differs from the ASCII variable length TIME structure used in the control headers.
Standard for the Exchange of Earthquake Data - Reference Manual • 33

Chapter 3

Field type

Chapter 3 • SEED Conventions
All binary 32 bit words begin on long-word boundaries, 16 bit words begin on word boundaries, and all bytes on byteboundaries. The fixed portion of the header always ends at the end of a long-word boundary, and each blockette is an
integer number of long-words in length. Data may be written in either Big Endian (68000) or Little Endian (VAX) word
order. There are two data fields in the Station Identifier Blockette [50] which indicate the word order used for eachstation. Decoding programs will automatically adapt to the specified word order. Negative numbers utilize standard two’s
complement representation. The data description language in the data dictionary, referred to by the Channel Identifier
Blockette [52] for the represented channel, governs byte swapping within the data. Mantissas and exponents for floating
point numbers are expressed as binary two’s complement integers. The most significant bit of the number (bit 15, or
the left most bit) is always set to zero for a positive number, and the most significant bit of the mantissa is in bit 14. For
negative numbers, the most significant bit is always set to one, and the integer is in two’s complement format.

Figure 11: High and Low Bits in a 16-Bit Word shown in Big Endian (68000) word order34 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 4

Chapter 4

V

Volume Index
Control Headers

Volume index control headers precede all data. Their primary purpose is to provide a directory to differentiate partsof the volume for network and event distributions. Only field station volumes use Field Volume Identifier Blockette [5].

Standard for the Exchange of Earthquake Data - Reference Manual • 35

Chapter 4 • Volume Index Control Headers[5] Field Volume Identifier Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Field Volume Identifier Blockette
005
Volume Index
Required
Not Applicable
Not Applicable

Field stations use the Field Volume Identifier Blockette [5], and usually produce only one volume. They should include
this blockette once at the beginning of each logical volume or sub- volume.
Note

Field nameType

Length

Mask or Flags

1

Blockette type 005

D

3

“###”

3

Version of format

D4“##.#”

2
4
5

Length of blockette
Logical record length
Beginning of volume

D
D
V

4
2

1—22

“####”“##”

TIME

Notes for fields:
1 		Standard blockette type identification number.
2 		Length of the entire blockette, including the 7 bytes in fields 1 and 2.
3 		Version number of the format, currently “V2.4.”
4 		Volume logical record length expressed as a power of 2. A 4096 byte record would be 12. Logical record lengths
can be from 256 bytes to 32,768 bytes. 4096 bytes is preferred.
5 		Nominal starting time of the volume. Since all data are normally flushed at tape termination time, all data should
start at nearly the same time. Record that time here. If, however, the data are not flushed, the time here should be
the time of the earliest — not necessarily the first — record of the logical volume. The calculations to arrive at
this time do not have to include the longer period data, as that data may have been buffered for a long time prior
to its recording on the current volume.

36 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 4 • Volume Index Control Headers[8] Telemetry Volume Identifier Blockette
Telemetry Volume Identifier Blockette
008
Volume Index
Optional
Optional
Optional

Field stations or networks can use the Telemetry Volume Identifier Blockette [8] when electronically transmitting SEED
data. Without this blockette, header records can take up an unnecessarily large amount of the transmission — especially if the receiver already has them from a prior transmission. We suggest using the Telemetry Volume Identifier
Blockette [8] as follows: 1) The transmitter should send this blockette with information on the effective start and end
times of the header information associated with the data to be transmitted. 2) The transmitter should follow this withthe data. 3) The receiver should then respond as to whether or not it needs additional header information (dictionaries,
station information, or channel and response information) for the received data. 4) If the receiver needs those headers,
the transmitter can send them. (NOTE: This blockette had not yet been used at the time this manual went to press.)
Note

Field nameType

Length

Mask or Flags

1

Blockette type 008

D

3

“###”

3

Version of format

D4“##.#”

2
4
5
6
7
8
9

10
11

12

Length of blockette

D

Logical record lengthD

Station identifierA

Location identifierA

Channel identifierA

Beginning of volume

V

End of volume

Station information effective date

Channel information effective date
Network Code

V
V
V
A

4
2
5
2
3

1—22
1—22
1—22
1—22
2

“####”
“##”

[UN]
[UN]
[UN]

TIME
TIME
TIME
TIME

[ULN]

Notes for fields:
1 		Standard blockette type identification number.
2 		Length of the entire blockette, including the 7 bytes in fields 1 and 2.
3 		Version number of the format, currently “V2.4.”
4 		Volume logical record length expressed as a power of 2. A 4096 byte record would be 12.
5 		This component’s station name.
6 		This component’s location code. (This is the array subcode to the station.)
7 		Standard channel identifier (see Appendix A).
8 		Nominal starting time of the transmitted volume.
9 		Ending time of the transmitted volume.
10

Time of associated station header information.

11

Time of associated channel information.

Standard for the Exchange of Earthquake Data - Reference Manual • 37

Chapter 4

Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:VChapter 4 • Volume Index Control Headers[10] Volume Identifier Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Volume Identifier Blockette
010
Volume Index
Not Applicable
Required
RequiredThis is the normal header blockette for station or event oriented network volumes. Include it once at the beginning of each
logical volume or sub-volume.
Sample:010009502.1121992,001,00:00:00.0000~1992,002,00:00:00.00
00~1993,029~IRIS _ DMC~Data for 1992,001~
Note

Field nameType

Length

Mask or Flags

1

Blockette type 010

D

3

“###”

3

Version of format

D4“##.#”

2
4
5
V2.3 V2.3 V2.3 -

6
7
8
9

Length of blockette
Logical record length
Beginning time
End time

Volume TimeOriginating Organization
Label

D
D
V
V
V
V
V

4
2

1—22
1—22
1—22

1—80

“####”
“##”

TIME
TIME
TIME

1—80

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

Version number of the format, currently “V2.4.”

4

Volume logical record length, expressed as a power of 2. A 4096 byte logical record would have “12” in this field.
Logical record lengths can be from 256 bytes to 32,768 bytes. 4096 bytes is preferred.

5

The earliest time seen in the time span list for this logical volume.

6

The latest time on the logical volume.

7

The actual date and time that the volume was written.

8

The organization writing the SEED volume.

9

An optional label that can be used to identify this SEED volume. For instance a label such as “Andaman Islands
Earthquake” could be designated, and this label is commonly used for referencing your SEED volume in a data
center request queue, if supplied. If there is no label a ~ must be inserted, indicating that this variable length field is
closed, with no entry.

38 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 4 • Volume Index Control Headers[11] Volume Station Header Index Blockette
Volume Station Header Index Blockette
011
VolumeNot Applicable
Required
RequiredThis is the index to the Station Identifier Blockettes [50] that appear later in the volume. This blockette refers to eachstation described in the station header section.
Sample:V0110054004AAK _ _ 000003ANMO _ 000007ANTO _ 000010BJI _ _ 000012
Note

Field nameType

Length

Mask or Flags

1

Blockette type 011

D

3

“###”

3

Number of stations

D

3

“###”

2

4
5

Length of blockette

D

REPEAT fields 4 — 5 for the Number of stations:
Station identifier code

Sequence number of station header

A

D

4

5
6

“####”“######”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. It is possible (but not very likely) that thisblockette could exceed 9999 bytes. In this case, the writer should cease writing stations into the index before it
exceeds 9999 bytes; close the blockette; write it out; and continue with a new blockette [11]. The count in field
3 should reflect the count in each blockette. The byte count in field 2 should represent the size of the individual
blockettes as they are written.

3

The number of stations that will be represented later by Station identifier Blockettes [50] in the station header
section. The next two fields each repeat, once per station, for the total number of stations.

4

The official station code assignment of the recording station, as assigned by the NEIC.

5

The sequence number of the logical record on the current logical volume that contains the Station Identifier
Blockette [50] for the station named in field 4. Since records must be flushed when the stations are written, thisindexing value will always be unique and will never refer to more than one station. Note that station identifier
blockette update records are not included here, as they combine with a primary blockette to form the station
header.

Standard for the Exchange of Earthquake Data - Reference Manual • 39

Chapter 4

Name:
Blockette Type:
Control Header:Index Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:VChapter 4 • Volume Index Control Headers[12] Volume Time Span Index Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Volume Time Span Index Blockette
012
Volume Index
Not Applicable
Required
RequiredThis blockette forms an index to the time spans that encompass the actual data. One index entry exists for each time spanrecorded later in the volume. Time spans are not used for field station type volumes. There should be one entry in thisindex for each time span control header. (For more information, see the notes for blockettes [70], [73], and [74].)
Sample:012006300011992,001,00:00:00.0000~1992,002,00:00:00.0000~000014
Note

Field nameType

Length

Mask or Flags

1

Blockette type 012

D

3

“###”

3

Number of spans in tableD4“####”

2

4
5
6

Length of blockette

D

REPEAT fields 4 — 6 for the Number of spans in table:

4“####”

Beginning of span

V

1—22

TIME

Sequence number of time span headerD6“######”End of span

V

1—22

TIME

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. It is possible (but not very likely) that thisblockette could exceed 9999 bytes. In this case, the writer should cease writing time spans to the index before it
exceeds 9999 bytes; close the blockette; write it out; and continue a new blockette. The count in field 3 shouldreflect the count in each blockette. The byte count in field 2 should represent the size of the individual blockettes as
they are written.

3

The number of time spans present in this blockette. The next three fields each repeat, once per time span, for the
total number of time spans.

4

The beginning time of the time span. This should be the same time as is in the Time Span Identifier Blockette [70]to which it refers.

5

The time span ending time.

6

The sequence number of the record on which the Time Span Identifier Blockette [70] referred to starts.

40 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5

Chapter 5A

Abbreviation Dictionary
Control Headers

Dictionary records let you use abbreviations to refer to lengthy descriptions without having to create external tables.
Blockettes [43] through [48] help reduce the amount of space used to specify intricate channel responses in that you
can write out the responses once, and refer to them with short lookup codes, thereby eliminating the need to repeat thesame information; they are almost identical to blockettes [53] through [58], but differ only in that they are set up for use
as response dictionary entries. Use them with the Response Reference Blockette [60].

Standard for the Exchange of Earthquake Data - Reference Manual • 41

Chapter 5 • Abbreviation Dictionary Control Headers[30] Data Format Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Data Format Dictionary Blockette030
Abbreviation Dictionaries
Required
Required
Required

All volumes, with the exception of miniSEED data records, (see Appendix G), must have a Data Format Dictionary
Blockette [30]. Each Channel Identifier Blockette [52] has a reference (field 16) back to a Data Format Dictionary
Blockette [30], so that SEED reading programs will know how to decode data for the channels. Because every kind of data
format requires an entry in the Data Format Dictionary Blockette [30], each recording network needs to list entries foreach data format, if a heterogeneous mix of data formats are included in a volume. This data format dictionary is used todecompress the data correctly.
Sample:0300087CDSNΔGain-RangedΔFormat~000200104M0~W2ΔD0-13ΔA-8191~D1415~P0:#0,1:#2,2:#4,3:#7~
Note

Field name

1
2
3
4
5
6

Blockette type — 030
D
Length of blockette
D
Short descriptive name
V
Data format identifier code
D
Data family typeD
Number of decoder keys
D
REPEAT field 7 for the Number of decoder keys:
Decoder keys
V

7

Type

Length

Mask or Flags

3
4
1—50
4
3
2

“###”
“####”[UNLPS]“####”
“###”
“##”

any

[UNLPS]

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes of fields 1 and 2.

3

A short name describing the data type. See Appendix D.

4A cross reference number, used in later blockettes, to indicate this particular dictionary entry. The writer programfor each volume creates this code, and it pertains to one particular volume only. The code is never guaranteed tohave meaning outside of that volume, and it may be different for any two volumes. Writers usually assign 1 for the
first code, then increment for each additional code. Because a unique code is assigned for each data type, it will be
unique in each blockette.

5

A field used by the data decoder to describe the data family type. This field tells a potential decoder program whatgeneral algorithm to use to decode the associated data. Each algorithm requires some number of decoder keys that
contain special additional information, enabling the algorithm to decode the data. See Appendix D for more information about decoders and some examples of their use. As of this manual’s printing, the currently defined family
types are:0

Integer format fixed interval data

1

Gain ranged fixed interval data

50

Integer differences compression

80

ASCII text with line control (for console logs)

81

Non-ASCII text (for other language character sets)

90

Opaque data

91

Blockette-only information

6

The number of decoder keys used by the data family type (see Appendix D).

7

The decoder keys used by the data family type. Place a tilde after each key in the sequence to separate them. See
Appendix D.

42 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[31] Comment Description Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Comment Description Blockette031
Abbreviation Dictionaries
Optional
Required if referred toRequired if referred toSample:03100720750StimeΔcorrectionΔdoesΔnotΔincludeΔleapΔsecond,Δ(-1000ms).~000

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6

Blockette type — 031
Length of blockette
Comment code key
Comment class code
Description of comment
Units of comment level

D
D
D
A
V
D

3
4
4
1
1—70
3

“###”
“####”“####”[U][UNLPS]“###”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

Code key used to uniquely identify comments. The code keys are assigned by any user’s convention, and may
not be consistent between volumes. (We hope that these codes might be standardized, so that reader programsmight automatically determine data quality from them.) See Appendix E for a sample set of comment codes.
Field 5 of Station Comment Blockette [51] and field 5 of Channel Comment Blockette [59] refer to this code key.

4

A single letter code, assigned by the user, which determines to what the code refers.

5

The comment’s text. A brief sentence should describe the condition. Use upper and lower case alphanumeric characters, with punctuation. (Comments may optionally contain a numeric value to denote magnitude,frequency, or some other value, giving numeric weight to the comment. For example, such a numeric value isoften used for time corrections, where it represents the number of milliseconds of the correction.)6

If a value is associated with the comment, place the unit lookup code from field 3 of the Units Abbreviation
Blockette [34] abbreviation dictionary here; otherwise this value would be zero.

Standard for the Exchange of Earthquake Data - Reference Manual • 43

Chapter 5

Station operators, data collection centers, and data management centers can add descriptive comments to data to
indicate problems encountered or special situations.

AChapter 5 • Abbreviation Dictionary Control Headers[32] Cited Source Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Cited Source Dictionary Blockette032
Abbreviation Dictionaries
Not Applicable
Optional
RequiredThis blockette identifies the contributing institution that provides the hypocenter and magnitude information. This
blockette is used in event oriented network volumes.

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6

Blockette type — 032
Length of blockette
Source lookup code
Name of publication/author
Date published/catalog
Publisher name

D
D
D
V
V
V

3
4
2
1—70
1—70
1—50

“###”
“####”“##”[UNLPS][UNLPS][UNLPS]

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes of fields 1 and 2.

3

A cross reference number, used in subsequent blockettes to indicate this particular dictionary entry. The writerprogram for each volume creates this number, and it pertains only to that particular volume. This number is neverguaranteed to have meaning outside of the volume, and it may be different for any given two volumes. Writing
programs usually assign 1 for the first code, and increment it for each subsequent code. Because a unique code is
assigned for each data type, it will be unique in each of these blockettes.

4

A standard name for the publication from which the epicenter/ hypocenter information was obtained.

5

Date published and catalog information for this citation from the publication.

6

The name of the publisher.

44 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[33] Generic Abbreviation Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Generic Abbreviation Blockette033
Abbreviation Dictionaries
Required
Required
Required
Chapter 5

Sample:0330055001(GSN)ΔGlobalΔSeismographΔNetworkΔ(IRIS/USGS)~

Note

Field nameType

Length

Mask or Flags

1
2
3
4

Blockette type — 033
Length of blockette
Abbreviation lookup code
Abbreviation description

D
D
D
V

3
4
3
1—50

“###”
“####”“###”[UNLPS]

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes of fields 1 and 2.

3

A cross reference code, used in later blockettes (field 10 of the Station Identifier Blockette [50], and field 6 of
the Channel Identifier Blockette [52]) to indicate this particular dictionary entry (see Appendix F). The writerprogram for each volume creates this code, and it pertains only to that particular volume. This number is neverguaranteed to have meaning outside of the volume, and it may be different for any two volumes.
Writing
programs usually assign 1 for the first code, and increment it for each succeeding code. Because a unique code is
assigned for each data type, it will be unique in each of these blockettes.

4

The descriptive text for the abbreviation, as a brief sentence. Use upper and lower case alphanumeric text.

Standard for the Exchange of Earthquake Data - Reference Manual • 45

A

Chapter 5 • Abbreviation Dictionary Control Headers[34] Units Abbreviations Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Units Abbreviations Blockette
034
Abbreviation Dictionaries
Required
Required
RequiredThis blockette defines the units of measurement in a standard, repeatable way. Mention each unit of measurement only
once.
Sample:0340044001M/S~VelocityΔinΔMetersΔPerΔSecond~

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5

Blockette type — 034
Length of blockette
Unit lookup code
Unit name
Unit description

D
D
D
V
V

3
4
3
1—20
0—50

“###”
“####”“###”[UNP][UNLPS]

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes of fields 1 and 2.

3

A unit lookup code, used in later blockettes to indicate this particular dictionary entry. As of this manual’s publication, the following fields and blockettes refer to this code:• field 6 of the Comment Description Dictionary Blockette [31]• field 6 of the Response (Poles & Zeros) Dictionary Blockette [43]• field 7 of the Response (Poles & Zeros) Dictionary Blockette [43]• field 6 of the Response (Coefficients) Blockette [44]• field 7 of the Response (Coefficients) Blockette [44]• field 5 of the Response List Blockette [45]• field 6 of the Response List Blockette [45]• field 5 of the Generic Response Blockette [46]• field 6 of the Generic Response Blockette [46]• field 6 of the Response (Polynomial) Dictionary Blockette [49]• field 7 of the Response (Polynomial) Dictionary Blockette [49]• field 8 of the Channel Identifier Blockette [52]• field 9 of the Channel Identifier Blockette [52]• field 5 of the Response (Poles & Zeros) Blockette [53]• field 6 of the Response (Poles & Zeros) Blockette [53]• field 5 of the Response (Coefficients) Blockette [54]• field 6 of the Response (Coefficients) Blockette [54]46 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers• field 4 of the Response List Blockette [55]• field 5 of the Response List Blockette [55]• field 4 of the Generic Response Blockette [56]• field 5 of the Generic Response Blockette [56]• field 6 of the Fir Response Blockette [61]• field 7 of the Fir Response Blockette [61]• field 5 of the Response (Polynomial) Blockette [62]The writing program for each volume creates this code, and it pertains only to that particular volume. This
number is never guaranteed to have meaning outside of the volume, and it may be different for any twovolumes. Writing programs usually assign 1 for the first code, and increment it for each succeeding code.
Because a unique code is assigned for each data type, it will be unique in each of these blockettes.
4

The basic unit name, formatted as FORTRAN-like equations with all alphabetic characters in upper case.
Specify exponents by the “**” format, and use parentheses sparingly — only when normal FORTRAN precedence would not be correct. Use the standard exponential notation (e.g., “1E-9” not “1*10**-9”) for powersof 10. Use SI units and their standard abbreviations whenever possible; spell out and do not abbreviate non-SI
units. For reasons of convertibility, abbreviations are represented in uppercase although this is not SI convention.
Units of ground motion are typically defined as:		Displacement
M		
Velocity		
M/S		
Acceleration
M/S**2

5

A description of the unit.

Standard for the Exchange of Earthquake Data - Reference Manual • 47

Chapter 5• field 6 of the Response (Polynomial) Blockette [62]AChapter 5 • Abbreviation Dictionary Control Headers[35] Beam Configuration Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Beam Configuration Blockette
035
Abbreviation Dictionaries
Optional
Optional
Optional

Use this blockette to describe the configuration of an instrument array for the synthetic output of a beam forming
algorithm. The beam blockette [400] refers to this dictionary in the data headers of the data section. This is the only
dictionary that is used directly by the data section; only the control header section uses all other dictionaries.

Note

Field name

1
2
3
4

Blockette type — 035
D3
Length of blockette
D
4
Beam lookup code
D3
Number of components
D
4
REPEAT fields 5 — 9 for the Number of components:
Station identifierA
5
Location identifier
A
2
Channel identifierA
3
Sub-channel identifierD
4Component weight
D
5

5
6
7
8
9

Type

Length

Mask or Flags“###”“####”“###”“####”
[UN]
[UN]
[UN]
“####”“#.###”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes of fields 1 and 2. Huge beam formings could cause the 9999
byte total limit or the 99 station limit to overflow. If this happens, write additional blockettes, each with the same
beam lookup code.

3

A cross reference code, used in later blockettes (as of this manual’s publication, only field 5 of the Beam Blockette[400]) to indicate this particular dictionary entry. The blockette is referred to by the beam blockette in the data
section. The writing program for each volume creates this code, and it pertains only to that particular volume. This
number is never guaranteed to have meaning outside of the volume, and it may be different for any two volumes.
Writing programs usually assign 1 for the first code, and increment it for each succeeding code. Because a uniquecode is assigned for each data type, it will be unique in each of these blockettes.

4

The number of components included in the repeat section that follows.

5This component’s station name. (See Appendix G for some station names and codes.)6

This component’s location code. (This is the array subcode to the station.)

7

Standard channel identifier (see Appendix A).

8

The sub-channel identifier of the component; for use when the input channel is multiplexed.

9

The weight that was given to this component in the calculations of this beam48 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[41] FIR Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:
Introduced in SEED version

FIR Dictionary Blockette041
Abbreviation Dictionaries
Some Response RequiredSome Response RequiredSome Response Required
2.2

Note

Field name

1
2
3
4
5
6
7
8

Blockette type — 041
D
Length of blockette
D
Response Lookup Key
D
Response Name
V
Symmetry CodeA
Signal In Units
D
Signal Out Units
D
Number of Factors
D
REPEAT field 9 for Number of Coefficients
FIR Coefficient
F

9

Type

Length

Mask or Flags

3
4
4
1— 25
1
3
3
4

“###”
“####”“####”
[UN_]
[U]
“###”
“###”
“####”

14“-#.#######E-##”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, inclusive of the 7 bytes in fields 1 and 2. This blockette could exceed the maximum
number of 9,999 characters. If so, continue on the next record. Field 4 should be set the same, but fields 5 — 7 insubsequent blockettes should be ignored.

3

The numeric key that is used by blockette [60], field 6, for referring to the response dictionaries. These numbers
are arbitrary, and are assigned only in context to a given volume. Zero is not a legal key.

4

A descriptive name for the response.

5

The symmetry code. Designates how the factors will be specified. See the tables that follow to see examples ofthese different types of symmetry.
A — No Symmetry - all Coefficients are specified.
Example:Coeff

Factor

Value

1

1

-1.1396359E+0222

6.5405190E+01

332.9333237E+02

44

6.8279054E+02

55

1.1961222E+03

6

61.8402642E+03

77

2.6360273E+03
Standard for the Exchange of Earthquake Data - Reference Manual • 49

Chapter 5

The FIR blockette is used to specify FIR (Finite Impulse Response) digital filter coefficients. It is an alternative toblockette [44] when specifying FIR filters. The blockette recognizes the various forms of filter symmetry and can
exploit them to reduce the number of factors specified in the blockette. See Response (Coefficients) Blockette [54] formore information.

AChapter 5 • Abbreviation Dictionary Control Headers
B — Odd number Coefficients with symmetry.
Example:Coeff Factor
1 & 251
2 & 242
3 & 233
4 & 224
5 & 215
6 & 20
6
7 & 197
8 & 188
9 & 179
10& 16 10
11& 15 11
12& 14 12
13
13

Value
-1.1396359E+02
6.5405190E+01
2.9333237E+02
6.8279054E+02
1.1961222E+03
1.8402642E+03
2.6360273E+03
3.4843128E+03
4.8191733E+03
5.4920540E+03
6.0588989E+03
6.3135828E+03
2.3400203E+02

C — Even number Coefficients with symmetry.
Example:Coeff Factor
1 & 241
2 & 232
3 & 223
4 & 214
5 & 205
6 & 196
7 & 187
8 & 178
9 & 169
10& 15 10
11& 14 11
12& 13 12

Value-1.1396359E+02
6.5405190E+01
2.9333237E+02
6.8279054E+02
1.1961222E+03
1.8402642E+03
2.6360273E+03
3.4843128E+03
4.8191733E+03
5.4920540E+03
6.0588989E+03
6.3135828E+03

6

A Unit Lookup Key that refers to the Units Abbreviation Blockette [34], field 3, for the units for the incoming signal
to this stage of the filter. It will usually be ground motion, volts, or counts, depending on where in the filter system
it is.

7

Like field 6, but for the stages output signal. Analog filters usually output volts, digital filters output counts.

8

The number of factors that follow.
A No Symmetry — All Coefficients specified
f = c. “f ” denotes number of factors, “c” is number of coefficients
B Odd — First half of all coefficients and center coefficient specified

f = c+1
2
C Even — First half of all coefficients specified

f = c29FIR Filter Coefficients.

50 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[42] Response (Polynomial) Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:
Introduced in SEED version

Response (Polynomial) Dictionary Blockette042
Abbreviation Dictionaries
Some Response RequiredSome Response RequiredSome Response Required
2.3
Chapter 5

Use this blockette to characterize the response of a non-linear sensor.

Note

Field name

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

Blockette type — 042
D3
Length of blockette
D
4
Response Lookup Key
D
4
Response Name
V
1-25
Transfer Function TypeA
1Stage Signal Input Units
D
3Stage Signal Output Units
D
3
Polynomial Approximation TypeA
1
Valid Frequency Units
A
1
Lower Valid Frequency BoundF
12Upper Valid Frequency BoundF
12
Lower Bound of Approximation
F
12
Upper Bound of Approximation
F
12
Maximum Absolute Error
F
12
Number of Polynomial CoefficientsD
3(Repeat fields 16 and 17 for each polynomial coefficient)
Polynomial CoefficientF
12Polynomial Coefficient Error
F
12

16
17

Type

Length

Mask or Flags“###”“####”“####”“[UN_]”
[U]
“###”
“###”
[U]
[U]
“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“###”“-#.#####E-##”“-#.#####E-##”

Notes for Fields:
1Standard blockette type identification number.

2

Length of entire blockette, including the 7 bytes in fields 1 and 2.

3

A unique cross reference number, used in later blockettes to indicate this particular entry.

4

The identifying name of this response. This field gives a unique name to each dictionary entry.

5

A single letter “P” describing this type of stage.

6

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the incoming
signal to this stage of the filter.

7

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the stages output signal.

8

A single character describing the type of polynomial approximation (this field is mandatory) [Note: The input
units (x) into the polynomial will most always be in Volts. The output units (pn(x)) will be in the units of field 5.]:
M — MacLaurin
pn(x) = a0 + a1*x + a2*x^2 + ... + an*x^nNote: The following three fields play no part in the calculation to recover Earth units (i.e. field 5) for this response.
If these fields are available from the instrumentation literature, they can be used in post-processing to assess thefrequency domain validity.
Standard for the Exchange of Earthquake Data - Reference Manual • 51

A

Chapter 5 • Abbreviation Dictionary Control Headers
9

A single character describing valid frequency units:

10

If available, the low frequency corner for which the sensor is valid. 0.0 if unknown or zero.

11

If available, the high frequency corner for which the sensor is valid. Nyquist if unknown.

12

Lower bound of approximation. This should be in units of 5.

13Upper bound of approximation. This should be in units of 5.

14

The maximum absolute error of the polynomial approximation. Put 0.0 if the value is unknown or actually zero.

15

The number of coefficients that follow in the polynomial approximation. The 49 polynomial coefficients are given
lowest order first and the number of coefficients is one more than the degree of the polynomial.

16

The value of the polynomial coefficient.

17

The error for field 12. Put 0.0 here if the value is unknown or actually zero. This error should be listed as a positive
value, but represents a +/- error (i.e. 2 standard deviations).

“A” — rad/sec“B” — Hz52 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[43] Response (Poles & Zeros) Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Response (Poles & Zeros) Dictionary Blockette043
Abbreviation Dictionaries
Some Response RequiredSome Response RequiredSome Response Required

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8
9

Blockette type — 043
Length of blockette
Response Lookup Key
Response Name
Response typeStage signal input units
Stage signal output units
AO normalization factor (1.0 if none)
Normalization frequency (Hz)

D
D
D
V
A
D
D
F
F

3
4
4
1-25
1
3
3
12
12

“###”
“####”“####”“[UN_]”
[U]
“###”
“###”
“-#.#####E-##”“-#.#####E-##”

10

Number of complex zeros
D
3
REPEAT fields 11 — 14 for the Number of complex zeros:
Real zeroF
12
Imaginary zeroF
12
Real zero error
F
12
Imaginary zero error
F
12

“###”

Number of complex poles
D
3
REPEAT fields 16 — 19 for the Number of complex poles:
Real poleF
12
Imaginary poleF
12Real pole error
F
12
Imaginary pole error
F
12

“###”

11
12
13
14
15
16
17
18
19

“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”

NOTE: See Response (Poles & Zeros) Blockette [53] for more information.
Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

A unique cross reference number, used in later blockettes to indicate this particular dictionary entry.

4

The identifying name of this response. This field gives a unique name to each dictionary entry.

5

A single character describing the type of stage:
A — Laplace transform analog response, in rad/sec
B — Analog response, in Hz
C — Composite (currently undefined)
D — Digital (Z - transform)

6

A unit lookup key that refers to the Units Abbreviation Blockette [34] for the units of the incoming signal to thisstage of the filter. This signal will usually be ground motion, volts, or counts, depending on where it is in thefilter system.
Standard for the Exchange of Earthquake Data - Reference Manual • 53

Chapter 5

NoteAChapter 5 • Abbreviation Dictionary Control Headers
7

Like field 6, but for the stage’s output signal. Analog filters usually emit volts, and digital filters usually emit counts.

8

An optional field, used as a multiplicative factor to normalize the filter. Otherwise, put 1.0 here.

9

The frequency, fn, in Hertz, at which the value in field 8 is normalized (if any).

10

The number of complex zeros that follow.

11

The real portion of the complex zero value.

12

The imaginary portion of the complex zero value.

13

The error for field 11. For example, if the value of real zero (field 11) were 200.0 and the error was 2 per cent, use
4.0 for the error value in field 12. Put 0.0 here if the value is unknown.

14

As in field 13, this is the error for field 12.

15

The number of poles that follow.

16

The real portion of the complex pole.

17

The imaginary portion of the complex pole.

18

The error value for field 16.

19

The error value for field 17.

54 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[44] Response (Coefficients) Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Response (Coefficients) Dictionary Blockette
044
Abbreviation Dictionaries
Some Response RequiredSome Response RequiredSome Response Required

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7

Blockette type — 044
Length of blockette
Response Lookup Key
Response Name
Response type
Signal input units
Signal output units

D
D
D
V
A
D
D

3
4
4
1-25
1
3
3

“###”
“####”“####”“[UN_]”
[U]
“###”
“###”

8

Number of numerators
D
4
REPEAT fields 9 — 10 for the Number of numerators:
Numerator coefficientF
12
Numerator error
F12“####”

Number of denominators
D
4
REPEAT fields 12 — 13 for the Number of denominators:
Denominator coefficientF
12
Denominator error
F12“####”

9
10
11
12
13

“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”

NOTE: See Response (Coefficients) Blockette [54] for more information.
Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

A unique cross reference number, used in later blockettes to indicate this particular dictionary entry. For continuation records of this type, use the same Response lookup key and append part 1, part 2 etc. to the responsename in field 4.

4The identifying name of this response. This field gives a unique name to each dictionary entry.

5

A single character describing the type of stage:
A — Laplace transform analog response, in rad/sec
B — Analog response, in Hz
C — Composite (currently undefined)
D — Digital (Z - transform)

6

A unit lookup key that refers to the Units Abbreviation Blockette [34] for the units of the incoming signal to thisstage of the filter. This signal will usually be ground motion, volts, or counts, depending on where it is in thefilter system.

7

Like field 6, but for the stage’s output signal. Analog filters usually emit volts, and digital filters usually emit
counts.

8

The number of numerator values that follow.

9

The numerator coefficient value.
Standard for the Exchange of Earthquake Data - Reference Manual • 55

Chapter 5

NoteAChapter 5 • Abbreviation Dictionary Control Headers
10

The error of field 9.

11

The number of denominator values that follow. Denominators are only used for IIR filters. FIR type filters use only
the numerator. If there are no denominators, place a zero here and stop the blockette.

12

The denominator coefficient value.

13

The error of field 12.

56 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[45] Response List Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Response List Dictionary Blockette
045
Abbreviation Dictionaries
Some Response RequiredSome Response RequiredSome Response Required

Field nameType

Length

Mask or Flags

1
2
3
4
5
6

Blockette type — 045
Length of blockette
Response Lookup Key
Response Name
Signal input units
Signal output units

D
D
D
V
D
D

3
4
4
1-25
3
3

“###”
“####”“####”“[UN_]”
“###”
“###”

7

Number of responses listed
D
4
REPEAT fields 8 — 12 for the Number of responses listed:
Frequency (Hz)F
12
Amplitude
F
12
Amplitude error
F
12Phase angle (degrees)F
12
Phase error (degrees)F12“####”

8
9
10
11
12

“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”

NOTE: See Response List Blockette [55] for more information.
Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

A unique cross reference number, used in later blockettes to indicate this particular dictionary entry.

4

The identifying name of this response. This field gives a unique name to each dictionary entry.

5

A unit lookup key that refers to the Units Abbreviation Blockette [34] for the units of the incoming signal to thisstage of the filter. This signal will usually be ground motion, volts, or counts, depending on where it is in thefilter system.

6

Like field 5, but for the stage’s output signal. Analog filters usually emit volts, and digital filters usually emit
counts.

7

The number of responses in the repeat block that follows.

8

The frequency of this response.

9

The amplitude of this response.

10

The error of the amplitude.

1

The phase angle at this frequency.

12

The error of the phase angle.

Standard for the Exchange of Earthquake Data - Reference Manual • 57

Chapter 5

NoteAChapter 5 • Abbreviation Dictionary Control Headers[46] Generic Response Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Generic Response Dictionary Blockette
046
Abbreviation Dictionaries
Some Response RequiredSome Response RequiredSome Response Required

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6

Blockette type — 046
Length of blockette
Response Lookup Key
Response Name
Signal input units
Signal output units

D
D
D
V
D
D

3
4
4
1-25
3
3

“###”
“####”“####”“[UN_]”
“###”
“###”

7

Number of corners listed
D
4
REPEAT fields 8 — 9 for the Number of corners listed:
Corner frequency (Hz)F
12Corner slope (db/decade)
F
12

8
9

“####”“-#.#####E-##”“-#.#####E-##”

NOTE: See Generic Response Blockette [56] for more information.
Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

A unique cross reference number, used in later blockettes to indicate this particular dictionary entry.

4

The identifying name of this response. This field gives a unique name to each dictionary entry.

5

A unit lookup key that refers to the Units Abbreviation Blockette [34] for the units of the incoming signal to thisstage of the filter. The signal will usually be ground motion, volts, or counts, depending on where it is in the filter
system.

6

Like field 5, but for the stage’s output signal. Analog filters usually emit volts, digital filters usually emit counts.

7

The number of response corner frequencies specified in the repeat block that follows.

8

The corner frequency.

9

The slope of the line after the corner, measured in db/decade.

58 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[47] Decimation Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Decimation Dictionary Blockette
047
Abbreviation Dictionaries
Required for Digital Stage
Required for Digital Stage
Required for Digital Stage

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8
9

Blockette type — 047
Length of blockette
Response Lookup Key
Response Name
Input sample rate
Decimation factor
Decimation offset
Estimated delay (seconds)
Correction applied (seconds)

D
D
D
V
F
D
D
F
F

3
4
4
1-25
10
5
5
11
11

“###”
“####”“####”“[UN_]”“#.####E-##”“#####”“#####”“-#.####E-##”“-#.####E-##”

NOTE: See Decimation Blockette [57] for more information.
Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

A unique cross reference number, used in later blockettes to indicate this particular dictionary entry.

4

The identifying name of this response. This field gives a unique name to each dictionary entry.

5

The incoming sample rate, in samples per second.

6

The decimation factor. When this number of samples are read in, one final sample comes out. Calculate theoutput sample rate by dividing field 5 by the decimation factor.

7

This field determines which sample is chosen for use. Make the value of this field greater than or equal to zero,
but less than the decimation factor. If you pick the first sample, set this field to zero. If you pick the second
sample, set it to 1, and so forth.

8

The estimated pure delay for the stage; it may or may not be also corrected in field 7. This field’s value isnominal, and may be unreliable.

9

The time shift applied to the time tag due to delay at this stage of the filter; a negative number indicating the 9 oftime added to the former time tag. The actual delay is difficult to estimate, and the correction applied neglects
dispersion. This field allows the user to know how much correction was used, in case a more accurate correction
is to be applied later. A zero here implies no correction was done.

Standard for the Exchange of Earthquake Data - Reference Manual • 59

Chapter 5

NoteAChapter 5 • Abbreviation Dictionary Control Headers[48] Channel Sensitivity/Gain Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Channel Sensitivity/Gain Dictionary Blockette
048
Abbreviation Dictionaries
Required
Required
Required

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6

Blockette type — 048
Length of blockette
Response Lookup Key
Response Name
Sensitivity/gain
Frequency (Hz)

D
D
D
V
F
F

3
4
4
1-25
12
12

“###”
“####”“####”“[UN_]”“-#.#####E-##”“-#.#####E-##”

7

Number of history values
D
2
REPEAT fields 8 — 10 for the Number of history values:
Sensitivity for calibration
F
12
Frequency of calibration sensitivity
F
12Time of above calibration
V
1—22

8
9
10

“##”
“-#.#####E-##”“-#.#####E-##”
TIME

NOTE: See Channel Sensitivity/Gain Blockette [58] for more information.
Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

A unique cross reference number, used in later blockettes to indicate this particular dictionary entry.

4

The identifying name of this response. This field gives a unique name to each dictionary entry.

5

The gain at this stage, or the sensitivity for the channel.

6

The frequency, f n, at which the value in field 5 is correct.

7

You may record any number of standard calibration values for a history of the calculation of the sensitivity value(calibration methods usually only give information about the final channel response, not the individual stages). This
field represents the number of calibration history entries that follow. If there is no history, or this is a gain value, put
zero here and stop the blockette.

8

The recorded amplitude value of this history entry.

9

The frequency for this calibration; you can use a zero for a step calibration.

10

The time when the calibration was done.

60 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 5 • Abbreviation Dictionary Control Headers[49] Response (Polynomial) Dictionary Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:
Introduced in SEED version

Response (Polynomial) Dictionary Blockette049
Abbreviation Dictionaries
Some Response RequiredSome Response RequiredSome Response Required
2.3

Note

Field nameType

Length

Mask or Flags

1

Blockette Type — 049

D

3

“###”

3

Response Lookup KeyD4“####”

2
4
5
6
7
8
9

10
11

12

13
14

15
16
17

Length of Blockette

D

Response Name

V

Transfer Function TypeA

Stage Signal Input Units

Stage Signal Output Units

Polynomial Approximation Type
Valid Frequency Units

Lower Valid Frequency Bound

Upper Valid Frequency Bound

Lower Bound of Approximation

Upper Bound of Approximation
Maximum Absolute Error

Number of Polynomial Coefficients

D
D
A
A
F
F
F
F
F

D

4
1-25
1

Polynomial Coefficient Error

F
F“[UN_]”
[U]

3

“###”

1

[U]

3
1

12
12
12
12
12
3

(Repeat fields 16 and 17 for each polynomial coefficient)
Polynomial Coefficient“####”

12
12

“###”
[U]

“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“###”“-#.#####E-##”“-#.#####E-##”

Notes for Fields:
1Standard blockette type identification number.

2

Length of entire blockette, including the 7 bytes in fields 1 and 2.

3

A unique cross reference number, used in later blockettes to indicate this particular entry.

4

The identifying name of this response. This field gives a unique name to each dictionary entry.

5

A single letter “P” describing this type of stage.

6

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the incoming
signal to this stage of the filter.

7

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the stages output signal.

8

A single character describing the type of polynomial approximation (this field is mandatory): (Note: The input
units (x) into the polynomial will most always be in Volts. The output units (pn(x)) will be in the units of field 5.)
M -- MacLaurin
pn(x) = a0 + a1*x + a2*x^2 + ... + an*x^nStandard for the Exchange of Earthquake Data - Reference Manual • 61

Chapter 5

Use this blockette to characterize the response of a non-linear sensor.

AChapter 5 • Abbreviation Dictionary Control Headers(Note: The following three fields play no part in the calculation to recover Earth units (ie field 5) for this response. If thesefields are available from the instrumentation literature, they can be used in post-processing to assess the frequency
domain validity.)
9

A single character describing valid frequency units:			“A” -- rad/sec

			“B” -- Hz

10

If available, the low frequency corner for which the sensor is valid. 0.0 if unknown or zero.

11

If available, the high frequency corner for which the sensor is valid. Nyquist if unknown.

12

Lower bound of approximation. This should be in units of 5.

13Upper bound of approximation. This should be in units of 5.

14

The maximum absolute error of the polynomial approximation. Put 0.0 if the value is unknown or actually zero.

15

The number of coefficients that follow in the polynomial approximation. The polynomial coefficients are given
lowest order first and the number of coefficients is one more than the degree of the polynomial.

16

The value of the polynomial coefficient.

17

The error for field 12. Put 0.0 here is the value is unknown or actually zero. This error should be listed as a positive
value, but represent a +/- error (ie 2 standard deviations).

62 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6

Chapter 6

S

StationControl Headers

The station header records contain all the configuration and identification information for the station and all its instruments. The SEED format provides a great deal of flexibility for associating recording channels to the station, including
the ability to support different data formats dynamically. For each new station, start a new logical record, set theremainder of any previous header records to blanks, and write it out.
For analog cascading, use the Response (Poles & Zeros) Blockette [53], and the Channel Sensitivity/Gain Blockette [58]if needed. For digital cascading, use the Response (Coefficients) Blockette [54], and the Decimation Blockette [57] orChannel Sensitivity/Gain Blockette [58] if needed. For additional documentation, you may also use the Response List
Blockette [55] or the Generic Response Blockette [56].

Standard for the Exchange of Earthquake Data - Reference Manual • 63

Chapter 6 • Station Control Headers[50] Station Identifier Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Station Identifier Blockette
050
StationRequired
Required
Required

Sample:0500098ANMOΔΔ+34.946200-106.456700+1740.00006001Albuquerque,ΔNewMexico,ΔUSA~0013210101989,241~
~NIU

V2.3-

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

Blockette type — 050
Length of blockette
Station call letters
Latitude (degrees)Longitude (degrees)
Elevation (m)Number of channels
Number of station comments
Site name
Network identifier code
32 bit word order
16 bit word orderStart effective date
End effective date
Update flag
Network Code

D
D
A
D
D
D
D
D
V
D
D
D
V
V
A
A

3
4
5
10
11
7
4
3
1—60
3
4
2
1—22
0—22
1
2

“###”
“####”[UN]“-##.######”“-###.######”“-####.#”“####”“###”[UNLPS]“###”“####”
“##”
TIME
TIME
[ULN]

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

Station call letters.

4

Earth latitude in degrees from the equator. Use a negative number for a southern latitude. The Station Identifier
Blockette [50] contains the latitude of the station address associated with the call letters in field 3 and is often
the same as the instruments’ coordinates in the Channel Identifier Blockettes [52]. Seismologists should use thecoordinates in the Channel Identifier Blockette [52] and site preparation teams should ensure that these numbers arecalculated as accurately as possible.

5

Earth longitude from Greenwich. A negative number denotes a western longitude.

6

Elevation of local ground level in meters.

7

The number of channels that follow, not including any channel update blockettes (optional; we recommend not using
this field and leaving it set to blanks).

8

The number of Station Comment Blockettes [51] that follow (optional; we recommend not using this field and leaving
it set to blanks).

9

The station site, usually as “Local town/city, major political subdivision (state/province), country/territory”.

10

The abbreviation lookup code (field 3) from the Generic Abbreviation Blockette [33] abbreviation dictionary, thatrefers to the network to which the station belongs. If you are coding from an experimental system, or from a specialsite or group collaboration, you can use an abbreviation to specify the contributors.

64 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers
11

The swap order in which 32-bit quantities are specified in the data headers. The swap order of the data itself is
specified for the channel in the data format dictionary. This dictionary entry describes the exact format of thedata with the data description language — see Appendix D. Some swap orders for computers are:Little Endian (Intel, etc.) — “0123”
Big Endian (Motorola, etc.) — “3210”
This order also applies to the FLOAT Binary Data Field.

1216-bit quantity byte swapping order (as for longword above), for the data headers only. Some swap orders forcomputers are:
Big Endian (Motorola, etc.) — “10”13

The earliest known date that information in this header record is correct (used with update records). Use the datewhen the database was last changed; if you do not know this date, use the start date of the volume.

14

The latest date when this information is correct. The minimum length of this field can be zero, implying that the
information is still correct.

15

The update flag indicates to what the data update records refer. Use update records to either describe changes tothe condition of a station during this volume or to refer to previous volumes (as errata distributions). Use one ofthese flags:
N

Effective dates pertain to these data

U

Control header updates information previously sent

See Appendix H for more information.
16

A two character alphanumeric identifier that uniquely identifies the network operator responsible for the datalogger. This identifier is assigned by the IRIS Data Management Center in consultation with the FDSN working
group on the SEED format. This code is repeated in field 7 of the fixed section of data headers. The current listof Network Codes is available online at: http://www.iris.edu/stations/networks.txt

NOTE: If information in the Station Identifier Blockette [50] were to be changed during the time interval of thevolume, additional blockettes with the new information and new effective dates would immediately follow the first
blockette (if there are several changes, there should be additional blockettes).
The 16 bit and 32 bit swap orders pertain only to the fields in the fixed headers and blockettes of the data records.
The swap order in the data section itself is described with the data description language (see Appendix D). All ofthese fields must be present and accurate for any decoder to operate correctly. These headers also mean that network
volumes can contain data with different swap orders. We recommend that network volumes convert data headers to aunified swapping arrangement, but the SEED format does not require this.
To eliminate a potential problem, all data records and blockettes for a given station must use the same byte ordering
within a SEED volume. In 2003, the FDSN adopted the format rule that Steim1 and Steim2 data records are to be
written with the big-endian encoding only. There is no DDL available to express a little-endian word order.

Standard for the Exchange of Earthquake Data - Reference Manual • 65

Chapter 6

Little Endian (Intel, etc.) — “01”S

Chapter 6 • Station Control Headers[51] Station Comment Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Station Comment Blockette
051
StationOptional
Optional
Optional

Sample:05100351992,001~1992,002~0740000000

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6

Blockette type — 051
Length of blockette
Beginning effective time
End effective time
Comment code key
Comment level

D
D
V
V
D
D

3
4
1—22
1—22
4
6

“###”
“####”
TIME
TIME“####”“######”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

The time when the comment comes into effect.

4

The time when the comment is no longer in effect.

5

The comment code key (field 3) of the associated Comment Description Dictionary Blockette [31] in the abbreviation dictionary section.

6

The numeric value associated with the level unit in the above Comment Description Dictionary Blockette [31] (ifany).

NOTE: Include any data outages and time corrections in the station comments.

66 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers[52] Channel Identifier Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Channel Identifier Blockette
052
StationRequired
Required
Required

0520119BHE0000004~001002+34.946200-106.456700+1740.0100.0090.0+00.0000112Δ2.000E+01Δ2.00
0E-030000CG~1991,042,20:48~~N

Chapter 6

Sample:S
Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

Blockette type — 052
Length of blockette
Location identifier
Channel identifier
Subchannel identifier
Instrument identifier
Optional comment
Units of signal response
Units of calibration input
Latitude (degrees)Longitude (degrees)
Elevation (m)Local depth (m)Azimuth (degrees)
Dip (degrees)
Data format identifier code
Data record length
Sample rate (Hz)Max clock drift (seconds)
Number of comments
Channel flags
Start dateEnd date
Update flag

D
D
A
A
D
D
V
D
D
D
D
D
D
D
D
D
D
F
F
D
V
V
V
A

3
4
2
3
4
3
0—30
3
3
10
11
7
5
5
5
4
2
10
10
4
0—26
1—22
0—22
1

“###”
“####”[UN][UN]“####”“###”[UNLPS]“###”“###”“-##.######”“-###.######”“-####.#”“###.#”“###.#”“-##.#”“####”“##”“#.####E-##”“#.####E-##”“####”
[U]
TIME
TIME

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

Describes the individual sites on an array station, operated by the same network operator. Do not use this field todistinguish multiple data loggers operated by different networks at the same station. Field 16 of blockette 50 isused for that purpose.

4Standard channel identifier (See Appendix A).

5

Used for a multiplexed data channel. (Normally, data are not multiplexed) The Data Format Dictionary Blockette[30] for this channel must correctly describe the multiplexing being used. Create a Channel Identifier Blockette[52] for each multiplexed subchannel.

6		An abbreviation lookup code (field 3) from the Generic Abbreviation Blockette [33] abbreviation dictionary that
contains a name for this instrument.
Standard for the Exchange of Earthquake Data - Reference Manual • 67

Chapter 6 • Station Control Headers
7

An optional comment given to the instrument. It can be any 30 character (or less) string, but as the mask [UNLPS]
indicates, underscores are not valid. This might include a serial number or a notation of special modifications.

8

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the signal response of the instrument. This is usually the ground motion response, such as M/S for velocity sensitive seismometers. These units
should be the same as the signal input units in the first filter stage (often a blockette 53).

9

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of calibration input,
usually volts or amps.

10

Latitude for the instrument. The Station Identifier Blockette [50] might contain different coordinates.

11

Longitude for the instrument.

12

Elevation of the instrument. To find the local ground depth, add the depth field to the instrument elevation. If
negative elevations are less than -9999 m, the decimal value should not be used. This allows depths up to -99999 m
to be accommodated, meaning that an instrument can be placed as deep as the Marianas trench, or as high as Mt.
Everest.

13

The local depth or overburden of the instrument’s location. For downhole instruments, the depth of the instrument
under the surface ground level. For underground vaults, the distance from the instrument to the local ground level
above. Surface instruments can use zero. If negative elevations are less than -999 m, the decimal value should not
be used. This allows depths up to -9999 m to be accommodated.

14

The azimuth of the instrument in degrees from north, clockwise.

15

The dip of the instrument in degrees, down from horizontal.
The azimuth and the dip describe the direction of the sensitive axis of the instrument (if applicable). Motionin the same direction as this axis is positive. SEED provides this field for non-traditional instruments or for
traditional instruments that have been oriented in some non-traditional way. Here are traditional orientations:Z — Dip -90, Azimuth 0 (Reversed: Dip 90, Azimuth 0)
N — Dip 0, Azimuth 0 (Reversed: Dip 0, Azimuth 180)
E — Dip 0, Azimuth 90 (Reversed: Dip 0, Azimuth 270)
Traditionally, the mass (boom) on vertical seismometers is oriented to the north, but sometimes this is not possible.
If you know the vertical orientation, place it in the azimuth field. If the orientation is 0 degrees, use an azimuth of
360.0. If you do not know the orientation, set the azimuth to 0.0.
If instruments are reversed in the field, reverse the dip/azimuth fields. Data collection centers and data management
centers should never actually modify the data, but report on its quality. User reading programs can automaticallyreverse the data if they report that they are doing so. Here are dip and azimuth examples of some tri-axial instruments:
A — Dip -60, Azimuth 0 (Reversed: Dip 60, Azimuth 180)
B — Dip -60, Azimuth 120 (Reversed: Dip 60, Azimuth 300)
C — Dip -60, Azimuth 240 (Reversed: Dip 60, Azimuth 60)

16

A data format lookup key that refers to field 4 of a Data Format Dictionary Blockette [30] that describes the formatof the data in the data section for this channel.

17

The exponent (as a power of two) of the record length for these data. The data record can be as small as 256 bytes
but never greater than 4096 bytes. Place a “12” in this field for a 4096 byte record. 4096 is preferred.

18

Sample rate in samples per second. This field contains the nominal sampling interval of the digitizer. This value isoverridden by information stored in the data Blockette [100] by SEED readers when these are provided in the data
record. (See Chapter 8, Blockette Type [100]. Therefore, use this field to indicate the nearest approximate integer
for sample rate. An example would be if you calculate a variable sample rate at the end of a time series, you may
calculate a variable sample rate. Don’t put that in this Blockette [52]. No considerations for drift or time correction
go here. Set this rate to zero for channels not sampled at regular intervals (such as console logs or alarms).

19

A tolerance value, measured in seconds per sample, used as a threshold for time error detection in the data. The
number of samples in a record are multiplied by this value to calculate a maximum drift allowed for the time in thenext record. If the difference in times is less than this drift, consider them in the same time series.

20

The number of Channel Comment Blockettes [59] that follow (optional; we recommend not using this field andleaving it set to blanks).

68 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers
21

Channel type flags:
T — Channel is triggered
C — Channel is recorded continuously
H — State of health data
G — Geophysical data
W — Weather or environmental data
F — Flag information (nominal, not ordinal)
I — Channel is a calibration input
E — Channel is experimental or temporary
M — Maintenance tests are underway on channel; possible abnormal data
B — Data are a beam synthesis
Here are some uses for the channel flags field:
G — Geophysical data:• Seismic (seismometer, geophone)• Earth electric field• Magnetic (magnetometer)• Gravity (gravimeter)• Tilt (tilt meter)• Strain (strain meter)
W — Weather or environmental data (readings inside vault/downhole or in equipment boxes may also be
State-of-Health [H]):• Wind speed or direction• Pressure• Temperature• Humidity• Precipitation
H — State of Health:• Power supply voltages• Status of system peripherals• Door open or closed• Room temperature• System temperature
F — Flag Information. Includes all on/off or go/no-go conditions, such as power supply okay, line power
okay, door open, or system too hot
B — Beam synthesis channel (Do not set the ‘S’ (synthetic) flag for beams)
S — Synthetic Data. Oddly oriented devices that have been rotated mathematically into a traditional orientation, or the output of a synthetic seismogram program should have the “S” flag set.

22

The earliest known date that information in this blockette is correct, or the response blockettes that follow thisblockette. Used with update records. If possible, list the time when the database was last changed; but if this dateis not known, use the start date of the volume.

23

The latest date when this information is correct. A zero length implies that the information was still valid whenthe volume was generated. Use this field for current volumes, when the final date is in the future. You can place
the date of the end of the volume here.
Standard for the Exchange of Earthquake Data - Reference Manual • 69

Chapter 6

S — Synthesized data

S

Chapter 6 • Station Control Headers
24

Indicate what data the update records refer to. Use update records to either denote changes to the condition of astation during this volume, or to refer to previous volumes in an errata distribution. Here are the possible values forthe flag:
N — Effective dates pertain to these data
U — Control header updates information previously sent

See Appendix H for more information.
NOTE: If any of the channel data in this blockette, or in the response blockettes that follow, changes during the timeinterval of the volume, repeat the Channel Identifier Blockette [52] after the last channel Blockette [58] or [59], with the
new effective date (even if data in the Channel Identifier blockette did not change). Then place any channel blockettes,
and their associated response blockettes, that changed, in succession again, because the cascade between Blockettes [52]and .Blockettes [59] are to be written in order and are bound by Channel Identifier Blockette [52] and either [58] or [59],depending on whether you write a Channel Comment Blockette [59]. It is not legal to write Channel Identifier Blockettes[52] one after the other.

70 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers[53] Response (Poles & Zeros) Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Response (Poles & Zeros) Blockette
053
StationSome Response RequiredSome Response RequiredSome Response Required

Sample:0530382BΔ1007008Δ7.87395E+00Δ5.00000E-02ΔΔ3
Δ0.00000E+00Δ0.00000E+00Δ0.00000E+00Δ0.00000E+00
Δ0.00000E+00Δ0.00000E+00Δ0.00000E+00Δ0.00000E+00-1.27000E+01Δ0.00000E+00Δ0.00000E+00Δ0.00000E+00ΔΔ4-1.96418E-03Δ1.96418E-03Δ0.00000E+00Δ0.00000E+00
S-1.96418E-03-1.96418E-03Δ0.00000E+00Δ0.00000E+00
53-6.23500E+00Δ7.81823E+00Δ0.00000E+00Δ0.00000E+00-6.23500E+00-7.81823E+00Δ0.00000E+00Δ0.00000E+00
Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8

Blockette type — 053
Length of blockette
Transfer function typeStage sequence number
Stage signal input units
Stage signal output units
AO normalization factor (1.0 if none)
Normalization frequency fn(Hz)

D
D
A
D
D
D
F
F

3
4
1
2
3
3
12
12

“###”
“####”
[U]
“##”
“###”
“###”
“-#.#####E-##”“-#.#####E-##”

9

Number of complex zeros
D
3
REPEAT fields 10 — 13 for the Number of complex zeros:
Real zeroF
12
Imaginary zeroF
12
Real zero error
F
12
Imaginary zero error
F
12

“###”

Number of complex poles
D
3
REPEAT fields 15 — 18 for the Number of complex poles:
Real poleF
12
Imaginary poleF
12Real pole error
F
12
Imaginary pole error
F
12

“###”

10
11
12
13
14
15
16
17
18

“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”

Standard for the Exchange of Earthquake Data - Reference Manual • 71

Chapter 6

Use this blockette for the analog stages of filter systems and for infinite impulse response (IIR) digital filters. Digital
filters usually have a Decimation Blockette [57] following, and most stages have a Sensitivity/Gain Blockette [58]following. The stage sequence takes into account the fact that newer seismic systems will contain combinations ofanalog and digital filtering, allowing different deconvolution algorithms to be run sequentially (in cascade). SEED
reserves the composite function to describe analog instruments with digital feedback circuitry. Stage order is the sameas the original convolution order. Use the original earth units for the input units of stage 1. Use digital counts for the
output units on the last stage. (See Appendix C for more information.)SChapter 6 • Station Control Headers
Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. This blockette could exceed the maximumof 9999 characters. If so, continue on the next record. Set field 4 the same, but ignore fields 5—8 in subsequent
blockettes (neither write nor read them).

3

A single character describing the type of stage:
A — Laplace transform analog response, in rad/sec
B — Analog response, in Hz
C — Composite (currently undefined)
D — Digital (Z - transform)

4

The identifying number of this stage. Stages are numbered starting at 1, with one response per stage (blockettes[53], [54], [55], or [56]), optionally followed by a Decimation Blockette [57] or a Sensitivity/ Gain Blockette [58].

5

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the incoming signal
to this stage of the filter. This signal will usually be ground motion, volts, or counts, depending on where it is in thefilter system.

6

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the stage’s output signal. Analog
filters usually emit volts, and digital filters usually emit counts.

7

This field is mandatory and must be set such that when you evaluate the polynomial at the reference frequency the
result will be 1.

8

The frequency f n,, in Hertz, at which the value in field 7 is normalized (if any).

9

The number of complex zeros that follow.

10

The real portion of the complex zero value.

11

The imaginary portion of the complex zero value.

12

The error for field 10. For example, if the value of real zero (field 10) were 200.0 and the error was 2 per cent, use
4.0 for the error value in field 12. Put 0.0 here if the value is unknown or is actually zero. This error should be listed
as a positive value, but represents a +/- error.

13

As in field 12, this is the error for field 11.

14

The number of poles that follow.

15

The real portion of the complex pole.

16

The imaginary portion of the complex pole.

17

The error value for field 15.

18

The error value for field 16.

72 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers[54] Response (Coefficients) Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Response (Poles & Zeros) Blockette
054
StationSome Response RequiredSome Response RequiredSome Response Required

This blockette is the only blockette that might overflow the maximum allowed value of 9,999 characters. If there are
more coefficients than fit in one record, list as many as will fit in the first occurrence of this blockette (the counts of
Number of numerators and Number of denominators would then be set to the number included, not the total number).
In the next record, put the remaining number. Be sure to write and read these blockettes in sequence, and be sure thatthe first few fields of both records are identical. Reading (and writing) programs have to be able to work with both
blockettes as one after reading (or before writing). In July 2007, the FDSN adopted a convention that requires thecoefficients to be listed in forward time order. As a reference, minimum-phase filters (which are asymmetric) should be
written with the largest values near the beginning of the coefficient list.
Sample of an asymetrical FIR filter (Quanterra F96CM), with coefficients listed in forward time order:
type 054 len 2328
: A040030030096+1.58748E-03+0.00000E+00+1.25059E-02+0.00000E+00+4.99939E-02+0.00000E+00+1.31099E-01+0.
: 00000E+00+2.45179E-01+0.00000E+00+3.32017E-01+0.00000E+00+3.07634E-01+0.00000E+00+1.43493E-01+0.0000: 0E+00-7.21612E-02+0.00000E+00-1.82592E-01+0.00000E+00-1.08383E-01+0.00000E+00+5.73389E-02+0.00000E+00+1: .34413E-01+0.00000E+00+5.07088E-02+0.00000E+00-7.87399E-02+0.00000E+00-9.53076E-02+0.00000E+00+7.987: 77E-03+0.00000E+00+8.75964E-02+0.00000E+00+4.37628E-02+0.00000E+00-5.24285E-02+0.00000E+00-6.68836E: 02+0.00000E+00+1.13016E-02+0.00000E+00+6.50235E-02+0.00000E+00+2.22038E-02+0.00000E+00-4.70865E-02+0: .00000E+00-4.20307E-02+0.00000E+00+2.24986E-02+0.00000E+00+4.76652E-02+0.00000E+00+1.17390E-03+0.000: 00E+00-4.19493E-02+0.00000E+00-1.91002E-02+0.00000E+00+2.92177E-02+0.00000E+00+2.91722E-02+0.00000E+: 00-1.39009E-02+0.00000E+00-3.14879E-02+0.00000E+00-3.59995E-04+0.00000E+00+2.76296E-02+0.00000E+00+1: .11628E-02+0.00000E+00-1.99142E-02+0.00000E+00-1.74256E-02+0.00000E+00+1.07445E-02+0.00000E+00+1.920: 93E-02+0.00000E+00-2.13720E-03+0.00000E+00-1.73854E-02+0.00000E+00-4.54401E-03+0.00000E+00+1.32485E: 02+0.00000E+00+8.66123E-03+0.00000E+00-8.17185E-03+0.00000E+00-1.02821E-02+0.00000E+00+3.13511E-03+0: .00000E+00+9.49588E-03+0.00000E+00+3.88783E-04+0.00000E+00-8.04331E-03+0.00000E+00-3.29680E-03+0.000: 00E+00+5.37866E-03+0.00000E+00+4.52224E-03+0.00000E+00-2.75848E-03+0.00000E+00-4.48416E-03+0.00000E+: 00+7.26857E-04+0.00000E+00+3.73429E-03+0.00000E+00+5.87488E-04+0.00000E+00-2.71260E-03+0.00000E+00-1: .26149E-03+0.00000E+00+1.70907E-03+0.00000E+00+1.45636E-03+0.00000E+00-8.81505E-04+0.00000E+00-1.346: 65E-03+0.00000E+00+2.87937E-04+0.00000E+00+1.08290E-03+0.00000E+00+7.88575E-05+0.00000E+00-7.75940E: 04+0.00000E+00-2.61277E-04+0.00000E+00+4.94951E-04+0.00000E+00+3.14315E-04+0.00000E+00-2.74088E-04+0: .00000E+00-2.89878E-04+0.00000E+00+1.21231E-04+0.00000E+00+2.29791E-04+0.00000E+00-2.90766E-05+0.000: 00E+00-1.62258E-04+0.00000E+00-1.70402E-05+0.00000E+00+1.03105E-04+0.00000E+00+3.31562E-05+0.00000E+: 00-5.89496E-05+0.00000E+00-3.25909E-05+0.00000E+00+2.99310E-05+0.00000E+00+2.50748E-05+0.00000E+00-1: .31724E-05+0.00000E+00-1.64432E-05+0.00000E+00+4.85992E-06+0.00000E+00+9.38671E-06+0.00000E+00-1.233: 77E-06+0.00000E+00-5.63954E-06+0.00000E+00+2.18465E-06+0.00000E+00+5.27728E-07+0.00000E+00+3.76714E: 09+0.00000E+000000

Standard for the Exchange of Earthquake Data - Reference Manual • 73

Chapter 6

This blockette is usually used only for finite impulse response (FIR) filter stages. You can express Laplace transforms
this way, but you should use the Response (Poles & Zeros) Blockettes [53] for this. You can express IIR filters thisway, but you should use the Response (Poles & Zeros) Blockette [53] here, too, to avoid numerical stability problems.
Usually, you will follow this blockette with a Decimation Blockette [57] and a Sensitivity/Gain Blockette [58] tocomplete the definition of the filter stage.

S

Chapter 6 • Station Control Headers
Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6

Blockette type — 054
Length of blockette
Response typeStage sequence number
Signal input units
Signal output units

D
D
A
D
D
D

3
4
1
2
3
3

“###”
“####”
[U]
“##”
“###”
“###”

7

Number of numerators
D
REPEAT fields 8 — 9 for the Number of numerators:
Numerator coefficientF
Numerator error
F4“####”

1212“-#.#####E-##”“-#.#####E-##”

8
9
10
11
12

Number of denominators
D
4
REPEAT fields 11 — 12 for the Number of denominators:
Denominator coefficientF
12
Denominator error
F12“####”“-#.#####E-##”“-#.#####E-##”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. This blockette could exceed the maximum of
9999 characters. If so, continue with another blockette [55] on the next record. Set field 4 the same, but ignore fields
5—6 in subsequent blockettes.

3

A single character describing the type of stage:
A — Analog (rad/sec)
B — Analog (Hz)C — Composite
D — Digital

4

The identifying number of the stage. Stages are numbered starting at 1. Use one response per stage (blockettes [53],[54], [55], or [56]); you may follow it with a Decimation Blockette [57] or a Sensitivity/Gain Blockette [58].

5

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the incoming signal
to this stage of the filter. This signal will usually be ground motion, volts, or counts, depending on where it is in thefilter system.

6

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the stage’s output signal. Analog
filters usually emit volts, and digital filters usually emit counts.

7

The number of numerator values that follow.

8

The numerator coefficient value.

9

The error of field 8.

10The number of denominator values that follow. Denominators are only used for IIR filters. FIR type filters use only
the numerator. If there are no denominators, place a zero 55 here and stop the blockette.

11

The denominator coefficient value.

12

The error of field 11.

74 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers[55] Response List Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Response List Blockette
055
StationSome Response RequiredSome Response RequiredSome Response Required
Chapter 6

This blockette alone is not an acceptable response description; always use this blockette along with the standard
response blockettes ([53], [54], [57], or [58]). If this is the only response available, we strongly recommend that you
derive the appropriate poles and zeros and include blockette 53 and blockette 58.

S
Note

Field nameType

Length

Mask or Flags

1
2
3
4
5

Blockette type — 055
Length of blockette
Stage sequence number
Signal input units
Signal output units

D
D
D
D
D

3
4
2
3
3

“###”
“####”
“##”
“###”
“###”

6

Number of responses listed
D
4
REPEAT fields 7 — 11 for the Number of responses listed:
Frequency (Hz)F
12
Amplitude
F
12
Amplitude error
F
12Phase angle (degrees)F
12
Phase error (degrees)
F
12

7
8
9
10
11

“####”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. This blockette could exceed the maximumof 9999 characters. If so, continue with another blockette [55] on the next record. Set field 3 the same, but ignore
fields 4 and 5 in subsequent blockettes.

3

The identifying number of the stage. Stages are numbered starting at 1.

4

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the incoming
signal to this stage of the filter. This signal will usually be ground motion, volts, or counts, depending on where
it is in the filter system.

5

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the stage’s output signal.
Analog filters usually emit volts, and digital filters usually emit counts.

6

The number of responses in the repeat block that follows.

7

The frequency of this response.

8

The amplitude of this response.

9

The error of the amplitude.

10

The phase angle at this frequency.

11

The absolute error of the phase angle.

Standard for the Exchange of Earthquake Data - Reference Manual • 75

Chapter 6 • Station Control Headers[56] Generic Response Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Generic Response Blockette
056
StationSome Response RequiredSome Response RequiredSome Response Required

This blockette alone is not an acceptable response description; always use this blockette along with the standard response
blockettes ([53], [54], [57], or [58]). You can, however, use this blockette alone to provide additional documentation.

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5

Blockette type — 056
Length of blockette
Stage sequence number
Signal input units
Signal output units

D
D
D
D
D

3
4
2
3
3

“###”
“####”
“##”
“###”
“###”

6

Number of corners listed
D
4
REPEAT fields 7 — 8 for the Number of corners listed:
Corner frequency (Hz)F
12Corner slope (db/decade)F12“####”

78“-#.#####E-##”“-#.#####E-##”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. This blockette could exceed the maximumof 9999 characters. If so, continue on the next record. Set field 3 the same, but ignore fields 4 and 5 in subsequent
blockettes.

3

The identifying number of the stage. Stages are numbered starting at 1.

4

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the incoming signal
to this stage of the filter. The signal will usually be ground motion, volts, or counts, depending on where it is in thefilter system.

5

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the stage’s output signal. Analog
filters usually emit volts, digital filters usually emit counts.

6

The number of response corner frequencies specified in the repeat block that follows.

7

The corner frequency.

8

The slope of the line to the right of the corner frequency, measured in db/decade.

76 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers[57] Decimation Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Decimation Blockette
057
StationRequired for Digital Stage
Required for Digital Stage
Required for Digital Stage

Sample:057005132∆.0000E+02∆∆∆∆1∆∆∆∆0∆0.0000E+00∆0.0000E+00
Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8

Blockette type — 057
Length of blockette
Stage sequence number
Input sample rate (Hz)
Decimation factor
Decimation offset
Estimated delay (seconds)
Correction applied (seconds)

D
D
D
F
D
D
F
F

3
4
2
10
5
5
11
11

“###”
“####”“##”“#.####E-##”“#####”“#####”“-#.####E-##”“-#.####E-##”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes infields 1 and 2.

3

The stage that is being decimated.

4

The incoming sample rate, in samples per second.

5

The decimation factor. When this number of samples
are read in, one final sample comes out. Calculate theoutput sample rate by dividing field 4 by the decimation
factor.

6

This field determines which sample is chosen for use.
Make the value of this field greater than or equal to zero,
but less than the decimation factor. If you pick the firstsample, set this field to zero. If you pick the second
sample, set it to 1, and so forth.

7

The estimated pure delay for the stage. This value willalmost always be positive to indicate a delayed signal.
Due to the difficulty in estimating the pure delay of astage and because dispersion is neglected this value
should be considered nominal. Normally the delay
would be corrected by the recording system and the correction applied would be specified in field 8. In mostcases field 7 and field 8 should be the same or very similar.

8

Illustration of stage delay (field 7) and correction applied (field 8).

The time shift applied to correct for the delay at this stage. This field uses a sign convention opposite that of field 7: a positive
value indicates time advance (shift in the direction opposite of the positive delay of field 7) and a negative value indicatestime delay (shift in the same direction of the positive delay of field 7). In common usage the estimated delay and correction
applied are both positive to cancel each other. Refer to the schematic delay below for a graphical representation of theseconventions. This correction does not account for dispersion. This field allows the user to know how much correction wasused in case a more accurate correction is to be applied later. A zero here indicates no correction was applied.

Standard for the Exchange of Earthquake Data - Reference Manual • 77

Chapter 6

Many digital filtration schemes process a high sample rate data stream; filter; then decimate, to produce the desired
output. Use this blockette to describe the decimation phase of the stage. You would usually place it between a Response(Coefficients) Blockette [54] and the Sensitivity/Gain Blockette [58] phases of the filtration stage of the channel. Include
this blockette with non-decimated stages because you must still specify the time delay. (In this case, the decimation
factor is 1 and the offset value is 0.)SChapter 6 • Station Control Headers[58] Channel Sensitivity/Gain Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Channel Sensitivity/Gain Blockette
058
StationRequired
Required
Required

When used as a gain (stage ≠ 0), this blockette is the gain for this stage at the given frequency. Different stages may be atdifferent frequencies. However, it is strongly recommended that the same frequency be used in all stages of a cascade, if
possible. When used as a sensitivity(stage=0), this blockette is the sensitivity (in counts per ground motion) for the entire
channel at a given frequency, and is also referred to as the overall gain. The frequency here may be different from thefrequencies in the gain specifications, but should be the same if possible. If you use cascading (more than one filter stage),then SEED requires a gain for each stage. A final sensitivity (Blockette [58], stage = 0, is required. If you do not use
cascading (only one stage), then SEED must see a gain, a sensitivity, or both.
Sample:0580035Δ3Δ3.27680E+03Δ0.00000E+00Δ0

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5

Blockette type — 058
Length of blockette
Stage sequence number
Sensitivity/gain (Sd)Frequency (Hz) (fs)

D
D
D
F
F

3
4
2
12
12

“###”
“####”“##”“-#.#####E-##”“-#.#####E-##”

6

Number of history values
D
2
REPEAT fields 7 — 9 for the Number of history values:
Sensitivity for calibration
F
12
Frequency of calibration (Hz)F
12Time of above calibration
V
1—22

7
8
9

“##”
“-#.#####E-##”“-#.#####E-##”
TIME

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. This blockette could exceed the maximum of
9999 characters, but it should never be necessary to record that much calibration history; usually a few values will
suffice.

3

The stage for which this gain applies. If you set this number to zero, SEED will consider it a channel sensitivity
value (overall gain).

4

The gain (Sd) at this stage, or the sensitivity (Sd) for the channel (depending on the value in field 3).

5

The frequency (fs) at which the value in 4 is correct.

6

You may record any number of standard calibration values for a history of the calculation of the sensitivity value(calibration methods usually only give information about the final channel response, not the individual stages). This
field represents the number of calibration history entries that follow. If there is no history, or this is a gain value, put
zero here and stop the blockette.

7

The recorded amplitude value of this history entry.

8

The frequency for this calibration; you can use a zero for a step calibration.

9

The time when the calibration was done.

78 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers[59] Channel Comment Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Channel Comment Blockette
059
StationOptional
Optional
Optional
Chapter 6

Sample:05900351989,001~1989,004~4410000000

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6

Blockette type — 059
Length of blockette
Beginning effective time
End effective time
Comment code key
Comment level

D
D
V
V
D
D

3
4
1—22
0—22
4
6

“###”
“####”
TIME
TIME“####”“######”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

The time when the comment comes into effect.

4

The time when the comment is no longer in effect.

5

The comment code key (field 3) of the associated Comment Description Dictionary Blockette [31] in the abbreviation dictionary section.

6

The numeric value (if any) associated with the Units of comment level (field 6) in the same Comment Description
Dictionary Blockette [31]. Together, this numeric value, its units, and the Description of comment (field 5) of theassociated Comment Description Blockette [31], all describe a comment for the channel.

Standard for the Exchange of Earthquake Data - Reference Manual • 79

S

Chapter 6 • Station Control Headers[60] Response Reference Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Response Reference Blockette
060
StationOptional
Optional
Optional

Use this blockette whenever you want to replace blockettes [53] through [58] and [61] with their dictionary counterparts,
blockettes [43] through [48] and [41]. We recommend placing responses in stage order, even if this means using more than
one Response Reference Blockette [60]. Here is an example:
Stage 1:

Response (Poles & Zeros) Blockette [53]Channel Sensitivity/Gain Blockette [58]First response reference blockette:
Response Reference Blockette [60]Stage 2:
[44]
[47]
[48]
Stage 3:
[44]
[47]
[48]
Stage 4:[44]
[47]
Channel Sensitivity/Gain Blockette [58]Stage 5:
Response (Coefficients) Blockette [54](End of first response reference blockette)
Second response reference blockette:
Response Reference Blockette [60]Stage 5 (continued):
[47]
[48]
Stage 6:
[44]
[47]
[48]
(End of second response reference blockette)
Substitute Response Reference Blockette [60] anywhere the original blockette would go, but be sure to place it in thesame position as the original would have gone. (Note that this blockette uses a repeating field (response reference) within
another repeating field (stage value). This is the only blockette in the current version (2.1) that has this “two dimensional”
structure.)

Note

Field nameType

Length

Mask or Flags

1
2

Blockette type — 060
Length of blockette

D
D

3
4

“###”
“####”

3

Number of stages
D
2“##”
REPEAT field 4, with appropriate fields 5 and 6, for each filter stage
Stage sequence number
D
2
“##”

4
5
6

Number of responses
D
2
REPEAT field 6, one for each response within each stage:
Response lookup key
D
4

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

The number of stages.

80 • Standard for the Exchange of Earthquake Data - Reference Manual“##”“####”

Chapter 6 • Station Control Headers
4

The stage sequence numbers — create one number (each number with a set of responses that follow) for each of
the total number of stages.

5

The number of responses within a stage.

6

The unique response lookup key — note one key for each of the total number of responses.

Chapter 6

S

Standard for the Exchange of Earthquake Data - Reference Manual • 81

Chapter 6 • Station Control Headers[61] FIR Response Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:
Introduced in SEED Version

FIR Response Blockette
061
Channel Response
Some Response RequiredSome Response RequiredSome Response Required
2.2

The FIR blockette is used to specify FIR (Finite Impulse Response) digital filter coefficients. It is an alternative toblockette [54] when specifying FIR filters. The blockette recognizes the various forms of filter symmetry and can exploit
them to reduce the number of factors specified to the blockette. In July 2007, the FDSN adopted a convention that requires
the coefficients to be listed in forward order as used in equation 8 of Appendix C. As a reference, minimum-phase filters(which are asymmetric) should be written with the largest values near the beginning of the coefficient list.
Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7

Blockette type — 061
Length of blockette
Stage sequence number
Response Name
Symmetry CodeSignal In Units
Signal Out Units

D
D
D
V
A
D
D

3
4
2
1 — 251
3
3“###”“####”
“##”
[UN_]
[U]
“###”
“###”

8

Number of CoefficientsD
REPEAT field 9 for the Number of Coefficients
FIR CoefficientF4“####”

14“-#.#######E-##”

9

Notes for Field
1Standard blockette type identification number.

2

Length of the entire blockette, inclusive of the 7 bytes in fields 1 and 2. This blockette could exceed the maximumof 9,999 characters. If so, continue on the next record. Field 4 should be set the same, but fields 5 — 7 in subsequent
blockettes should be ignored.

3

The identifying number of the stage.

4

A descriptive name for the response.

5

The symmetry code. Designates how the factors will be specified. See the tables that follow to see examples ofthese different types of symmetry.
A — No Symmetry - all Coefficients are specified.
Example:Coeff

Factor

Value

1

1

-.113963588000E+03

22.654051896200E+0233.293332365600E+03

44.682790540100E+03

55.119612218000E+04

66.184026419900E+04

77.263602733900E+04

B — Odd number Coefficients with symmetry
Example:Coeff

FactorValue

1 & 25
1- .113963588000E+03
82 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers2.654051896200E+02

3 & 233.293332365600E+03

4 & 224.682790540100E+03

5 & 21

5.119612218000E+04

6 & 206.184026419900E+04

7 & 197.263602733900E+04

8 & 188.348431282900E+04

9 & 179.481917329000E+04

10& 1610.549205395300E+04

11& 15

11.605889892900E+04

12& 1412.631358277400E+04

1313.234002034020E+03

C — Even number Coefficients with symmetry.
Example:Coeff

FactorValue

1 & 241-.113963588000E+03

2 & 232.654051896200E+02

3 & 223.293332365600E+03

4 & 214.682790540100E+03

5 & 205.119612218000E+04

6 & 196.184026419900E+04

7 & 187.263602733900E+04

8 & 178.348431282900E+04

9 & 169.481917329000E+04

10& 1510.549205395300E+04

11& 1411.605889892900E+04

12& 1312.631358277400E+04

6

A Unit Lookup Key that refers to the Units Abbreviation Blockette [34], field 3, for the units for the incoming
signal to this stage of the filter. Will usually be ground motion, volts, or counts, depending on where in the filter
system it is.

7

Like field 6, but for the stages output signal. Analog filters usually output volts, digital filters output counts.

8

The number of factors that follow.
A No Symmetry — All Coefficients specified
f = c. “f ” denotes number of factors, “c” is number of coefficients
B Odd — First half of all coefficients and center coefficient specified

f=

c+1
2

C Even — First half of all coefficients specified

f=
9

c
2

FIR Filter Coefficients.

Standard for the Exchange of Earthquake Data - Reference Manual • 83

Chapter 6

2 & 24S

Chapter 6 • Station Control Headers[62] Response [Polynomial] Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:
Introduced in SEED Version

Response (Polynomial) Blockette
062
Channel Response
Some Response RequiredSome Response RequiredSome Response Required
2.3

Use this blockette to characterize the response of the entire system or a a component (e.g. sensor) of the system. Whenused in stage 0 the polynomial should describe the conversion from the sample values to Earth units. When used within
the response cascade (stages >= 1) the polynomial should represent a single component of the system. A stage 0 polynomial should always be present to facilitate conversion of the data to Earth units when any component of the system
is described using a polynomial. As a simplification, a complete response may be specified with only a polynomial
specified in stage 0. (See examples below.) When any system is described using a polynomial, a blockette 58 should not
be present in stage 0 (sensitivity); unless the polynomial describes a linear transform a total sensitivity scalar cannot becorrect. Unlike most other response blockettes that describe a filter representing a component during data acquisition, thepolynomial describes a function to be applied to the data.

Note

Field name

1
2
3
4
5
6
7
8
9
10
11
12
13
14

Blockette type — 062
D3
Length of blockette
D
4Transfer Function TypeA
1Stage Sequence NumberD
2Stage Signal Input Units
D
3Stage Signal Output Units
D
3
Polynomial Approximation TypeA
1
Valid Frequency Units
A
1
Lower Valid Frequency BoundF
12Upper Valid Frequency BoundF
12
Lower Bound of Approximation
F
12
Upper Bound of Approximation
F
12
Maximum Absolute Error
F
12
Number of Polynomial Coefficients
D
3(REPEAT fields 15 and 16 for each polynomial coefficient)
Polynomial CoefficientF
12Polynomial Coefficient Error
F
12

15
16

Type

Length

Mask or Flags“###”“####”
[U]
“##”
“###”
“###”
[U]
[U]
“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“-#.#####E-##”“###”“-#.#####E-##”“-#.#####E-##”

Notes for Fields.
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

A single letter “P” describing the type of stage.

4

The identifying number of this stage.

5

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the incoming signal
to this stage from the system perspective. These are the units of the dependent variable (e.g. Earth units) that result
from applying the polynomial.

6

A unit lookup key that refers to field 3 of the Units Abbreviation Blockette [34] for the units of the output signal fromthis stage from the system perspective. These are the units of the independent variable (e.g. Counts, Volts) that areused as inputs to the polynomial.

84 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers
7

A single character describing the type of polynomial approximation (this field is mandatory): (Note: The input
units (x) into the polynomial will most always be in Volts. The output units [pn(x)] will be in the units of field 5.)
M - MacLaurin
pn(x)=a0+a1*x+a2*x^2+...+an*x^n(Note: The following three fields play no part in the calculation to recover Earth units [i.e., field 5] for this response. If
these fields are available from the instrumentation literature, they can be used in post-processing to assess the frequency
domain validity.
8

A single character describing valid frequency units for the values in fields 8 and 9:9

If available, the low frequency corner for which the sensor is valid. 0.0 if unknown or zero.

Chapter 6“A” — radians/second

10

If available, the high frequency corner for which the sensor is valid. Nyquist if unknown.

11

Lower bound of approximation. This should be in units described by field 5.

S

12Upper bound of approximation. This should be in units described by field 5.

13

The maximum absolute error of the polynomial approximation. Put 0.0 if the value is unknown or actually zero.

14

The number of coefficients that follow in the polynomial approximation. The polynomial coefficients are given
lowest order first and the number of coefficients is one more than the degree of the polynomial.

15

The value of the polynomial coefficient.

16

The error for field 12. Put 0.0 here if the value is unknown or actually zero. This error should be listed as apositive value, but represent a +/- error (i.e. 2 standard deviations).

“B” — Hertz

Examples:
1. Polynomial representation of the pressure response of a Setra Model 270 Pressure Transducer.
The Setra Model 270 Pressure Transducer is listed as valid between 600 mbar and 1100 mbar with a nominal output of
0-5 volts and it is presumed to be linear with respect to pressure. I haven’t found any error representation. No frequency
bounds are given for the transducer.
pn(x) = a0 + a1*x
where x = voltage, and pn(x) = pressure
Using 0 volts and then 5 volts input with the pressure range, we get:a0 = 600

a0 error = 0.0

a1 = 100

a1 error = 0.0

Standard for the Exchange of Earthquake Data - Reference Manual • 85

Chapter 6 • Station Control Headers
Sample voltage to pressure conversion:
Pressure (mbar)
Volts(x)
pn(x)
0.0
1.0
2.0
3.0
4.0
5.0

600
700
800
900
1000
1100

Bound Values for polynomial:
Lower

600 mbar

Upper

1100 mbar

Assume we use an 8 bit digitizer where 0 counts = 0 volts and 255
counts = 5 volts. This translates to a digitizer gain of 51 Counts/volt.
This provides the following conversion from counts to pressure:
CountsPressure (mbar)
Volts (x)gain*counts
pn(x)
0
51
102
153
204
255

0.0
1.0
2.0
3.0
4.0
5.0

600
700
800
900
1000
1100

The Polynomial Blockette representation for this sensor:
Field name
Blockette type
Length of blockette
Transfer Function TypeStage Sequence Number
Stage Signal Input Units
Stage Signal Output Units
Polynomial Approximation Type
Valid Frequency Units
Lower Valid Frequency Bound
Upper Valid Frequency Bound
Lower Bound of Approximation
Upper Bound of Approximation
Maximum Absolute Error
Number of Polynomial Coefficientsa0 Polynomial Coefficient
a0 Polynomial Coefficient Error
a1 Polynomial Coefficient
a1 Polynomial Coefficient Error

Type
D
D
A
D
D
D
A
A
F
F
F
F
F
D
F
F

Length
3
4
1
2
3
3
1
1
12
12
12
12
12
3
12
12

86 • Standard for the Exchange of Earthquake Data - Reference Manual

Mask or Flags
“062”
“129”
“P”
“??”
“???”
“???”
“M”
“B”
“0.00000E+00”“0.00000E+00”“ 6.00000E+02”“ 1.10000E+03”“0.00000E+00”“ 2”“ 6.00000E+02”“ 0.00000E+00”“1.00000E+02“ 0.00000E+00”

Chapter 6 • Station Control Headers
2. Polynomial representation of the temperature response of a thermistor.
In order to sense the temperature of the Berkeley Digital Seismic Network (BDSN) seismometers, we use a Yellow
Springs Instrument Co. (YSI) 44031 thermistor. To convert the thermistor resistance to a usable voltage signal, we haveinstalled the thermistor into a bridge amplification circuit. The calibrated response is:Temperature
-5.02
-4.43
-3.81
-3.18
-2.53
-1.85
-1.15
-0.43
0.32
1.10
1.92
2.76
3.64
4.56
5.52
6.53
7.60
8.72
9.90
11.15
12.49
13.91
15.43
17.07
18.85
20.78
22.91
25.25
27.88
30.85
34.26
38.26
43.07
49.09
57.04
68.59

Chapter 6

Voltage
-2.00
-1.90
-1.80
-1.70
-1.60
-1.50
-1.40
-1.30
-1.20
-1.10
-1.00
-0.90
-0.80
-0.70
-0.60
-0.50
-0.40
-0.30
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50

S

The resistance of the thermistor is a non-linear function of the temperature and its response can be described by apolynomial. YSI claims that all 44031 thermistors fall within 0.2 degrees C of the nominal response so we want tomodel the response to at least an accuracy of 0.2 degrees C. This temperature response can be adequately represented
by a McLaurin polynomial of the form:
pn(x) = a0 + a1*x + a2*x^2 + ... + an*x^nwhere x is the voltage and pn(x) is the temperature. The coefficients required to approximate the above temperaturevoltage data to the desired accuracy are:Standard for the Exchange of Earthquake Data - Reference Manual • 87

Chapter 6 • Station Control Headers
Coefficient
a0
a1
a2
a3
a4
a5
a6
a7
a8
a9
a10

Value
0.12505E+02
0.13824E+02
0.41039E+01
0.12932E+01
0.18741E+01
0.17250E+01-0.61021E+00-0.10540E+01
0.13974E+00
0.39061E+00
0.95345E-01

Error
0.14223E-03
0.22350E-02
0.86810E-02
0.44581E-01
0.34469E-01
0.91194E-01
0.22029E-01
0.28643E-01
0.39675E-02
0.10566E-02
0.15096E-03

The maximum error of the polynomial representation is -0.072 degrees C at a temperature of 57 degrees C and the temperature bounds are:
Bound

Value

Lower

-5.02

Upper

68.59

The parameter that is the most difficult to quantify is the frequency response of the thermistor. YSI states that the thermistor time constant varies from second in well-stirred oil to 10 seconds in still air. We have encapsulated the thermistor andits leads in heat-shrink tubing for protection from mechanical damage and this has the effect of lengthening the thermistor
time constant. We estimate the thermal time constant of the thermistor to be of order 20 seconds. However, the thermistor
assembly is placed inside a heavily insulated BDSN pier and seismometer enclosure that has a thermal time constant oforder several hours to a few days. Thus the temperature sensed by the thermistor varies so slowly that the thermistor time
constant is not significant.

88 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers
The Polynomial Blockette representation for this sensor:
Type
D
D
A
D
D
D
A
A
F
F
F
F
F
D
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F

Length
3
4
1
2
3
3
1
1
12
12
12
12
12
3
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12

Mask or Flags
“062”
“345”
“P”
“??”
“???”
“???”
“M”
“B”
“ 0.00000E+00”“ 0.10000E-01”“-5.0200E-00”“ 6.85900E+01”“ 0.72000E-01”“ 11”“ 0.12505E+02”“ 0.14223E-03”“ 0.13824E+02”“ 0.22350E-02”“ 0.41039E+01”“ 0.86810E-02”“ 0.12932E+01”“ 0.44581E-01”“ 0.18741E+01”“ 0.34469E-01”“ 0.17250E+01”“ 0.91194E-01”“-0.61021E+00”“ 0.22029E-01”“-0.10540E+01”“ 0.28643E-01”“ 0.13974E+00”“ 0.39675E-02”“ 0.39061E+00”“ 0.10566E-02”“ 0.95345E-01”“ 0.15096E-03”

Standard for the Exchange of Earthquake Data - Reference Manual • 89

Chapter 6

Field name
Blockette type
Length of blockette
Transfer Function TypeStage Sequence Number
Stage Signal Input Units
Stage Signal Output Units
Polynomial Approximation Type
Valid Frequency Units
Lower Valid Frequency Bound
Upper Valid Frequency Bound
Lower Bound of Approximation
Upper Bound of Approximation
Maximum Absolute Error
Number of Polynomial Coefficientsa0 Polynomial Coefficient
a0 Polynomial Coefficient Error
a1 Polynomial Coefficient
a1 Polynomial Coefficient Error
a2 Polynomial Coefficienta2 Polynomial Coefficient Error
a3 Polynomial Coefficienta3 Polynomial Coefficient Error
a4 Polynomial Coefficienta4 Polynomial Coefficient Error
a5 Polynomial Coefficient
a5 Polynomial Coefficient Error
a6 Polynomial Coefficienta6 Polynomial Coefficient Error
a7 Polynomial Coefficienta7 Polynomial Coefficient Error
a8 Polynomial Coefficient
a8 Polynomial Coefficient Error
a9 Polynomial Coefficient
a9 Polynomial Coefficient Error
a10 Polynomial Coefficient
a10 Polynomial Coefficient Error

SChapter 6 • Station Control Headers
Calculating a stage 0 polynomial
To calculate a polynomial representing the full acquisition system appropriate for stage 0 the linear gains from all otherstages must be incorporated into the polynomial used to represent the sensor, as illustrated in Example 2. The coefficientsof the stage 0 polynomial (p0, …, pn) are calculated by combining the polynomial for the sensor (usually stage 1) and thestage gains in the following way:p0 = a0p1 = a1/g0
p2 = a2/(g0**2)...
pn = an/(g0**n)
Where (a0, …, an) are the polynomial coefficients for the sensor (stage 1) and g0 is the product of the linear stage gains
from all other stages.
Examples:
1. An example SEED sequence that uses only a blockette 62 to describe the entire system (stage 0). While this is enoughinformation to convert the raw data to Earth units it is preferable to create a full cascade to document the acquisition
system if the information is available.
#####################################################################################
B050F03
Station:ANTO
B050F16
Network:
IU
B052F03
Location:
30
B052F04
Channel:LDO
B052F22
Start date: 2010,204,00:00:00
B052F23
End date:
2599,365,23:59:59##+-----------------------------------+#|
Response (Polynomial)|#|
IU ANTO
30 LDO|#|
07/23/2010 to 12/31/2599|#+-----------------------------------+#
B062F03
Transfer function type:P
B062F04
Stage sequence number:
0B062F05
Response in units lookup:
PA - Pressure in Pascals
B062F06
Response out units lookup:
COUNTS - Digital Counts
B062F07
Polynomial Approximation Type:M
B062F08
Valid Frequency Units:
B
B062F09
Lower Valid Frequency Bound:+0.00000E+00
B062F10Upper Valid Frequency Bound:+5.00000E-01
B062F11Lower Bound of Approximation:+8.00000E+04
B062F12Upper Bound of Approximation:+1.10000E+05
B062F13
Maximum Absolute Error:+0.00000E+00
B062F14
Number of coefficients:
2#
Polynomial coefficients:#
i, coefficient, error
B062F15-16
0 +8.00000E+04 +0.00000E+00
B062F15-16
1 +1.43050E-02 +0.00000E+00

90 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers
2. An example SEED sequence for a full cascade response using blockette 62 to describe the sensor (stage 1) followedby other stages describing the acquisition system and finally another blockette 62 to describe the entire system (stage
0).

Standard for the Exchange of Earthquake Data - Reference Manual • 91

Chapter 6#####################################################################################
B050F03
Station:
CMB
B050F16
Network:
BK
B052F03
Location:??
B052F04
Channel:LKS
B052F22
Start date: 2004,167,00:00:00
B052F23
End date:
2010,351,00:00:00##+-----------------------------------+#|
Response (Polynomial)|#|
BK CMB
LKS|#|
06/15/2004 to 12/17/2010|#+-----------------------------------+#
B062F03
Transfer function type:P
B062F04
Stage sequence number:
1
B062F05
Response in units lookup:
C - Degrees Centigrade
B062F06
Response out units lookup:
V - Volts
B062F07
Polynomial Approximation Type:M
B062F08
Valid Frequency Units:
B
B062F09
Lower Valid Frequency Bound:+0.00000E+00
B062F10Upper Valid Frequency Bound:+1.60000E-02
B062F11Lower Bound of Approximation:+3.40000E+00
B062F12Upper Bound of Approximation:+6.80000E+01
B062F13
Maximum Absolute Error:+1.00000E-01
B062F14
Number of coefficients:
10#
Polynomial coefficients:#
i, coefficient, error
B062F15-16
0 +1.25091E+01 +0.00000E+00
B062F15-16
1 +1.38687E+01 +0.00000E+00
B062F15-16
2 +4.31802E+00 +0.00000E+00
B062F15-16
3 +1.44163E+00 +0.00000E+00
B062F15-16
4 +8.29113E-01 +0.00000E+00
B062F15-16
5 +7.38976E-01 +0.00000E+00
B062F15-16
6 +4.10940E-01 +0.00000E+00
B062F15-16
7 +1.21068E-01 +0.00000E+00
B062F15-16
8 +1.78560E-02 +0.00000E+00
B062F15-16
9 +1.04300E-03 +0.00000E+00##+-----------------------------------+#|
Response (Coefficients)|#|
BK CMB
LKS|#|
06/15/2004 to 12/17/2010|#+-----------------------------------+#
B054F03
Transfer function type:D
B054F04
Stage sequence number:
2
B054F05
Response in units lookup:
V - Volts
B054F06
Response out units lookup:
COUNTS - Digital Counts
B054F07
Number of numerators:
0
B054F10
Number of denominators:0##+-----------------------------------+#|
Decimation|#|
BK CMB
LKS|#|
06/15/2004 to 12/17/2010|#+-----------------------------------+#
B057F03
Stage sequence number:
2
B057F04
Input sample rate (HZ):
5.1200E+03
B057F05
Decimation factor:
00001
B057F06
Decimation offset:
00000
B057F07
Estimated delay (seconds):+0.0000E+00
B057F08
Correction applied (seconds):+0.0000E+00##+-----------------------------------+#|
Channel Sensitivity/Gain|#|
BK CMB
LKS|#|
06/15/2004 to 12/17/2010|#+-----------------------------------+#
B058F03
Stage sequence number:
2
B058F04
Sensitivity:+4.13769E+05
B058F05
Frequency of sensitivity:+1.00000E-02
B058F06
Number of calibrations:0##+-----------------------------------+#|FIR Response|#|
BK CMB
LKS|#|
06/15/2004 to 12/17/2010|#+-----------------------------------+#

S

Chapter 6 • Station Control Headers
B061F03
B061F04
B061F05
B061F06
B061F07
B061F08#
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
#
#
#
#
#
#
#
B057F03
B057F04
B057F05
B057F06
B057F07
B057F08
#
#
#
#
#
#
#
B058F03
B058F04
B058F05
B058F06
#
#
#
#
#
#
#
B061F03
B061F04
B061F05
B061F06
B061F07
B061F08#
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09

Stage sequence number:
Response Name:
Symmetry Code:Response in units lookup:
Response out units lookup:
Number of Coefficients:
i FIR Coefficient
0 -1.11328E-03
1 -1.00800E-03
2 -1.35286E-03
3 -1.73045E-03
4 -2.08418E-03
5 -2.38538E-03
6 -2.60956E-03
7 -2.73352E-03
8 -2.73316E-03
9 -2.58472E-03
10 -2.26412E-03
11 -1.74847E-03
12 -1.01403E-03
13 -3.51682E-05
14 +1.23782E-03
15 +3.15983E-03
16 +6.99945E-03
17 +9.09960E-03
18 +1.25424E-02
19 +1.63123E-02
20 +2.02632E-02
21 +2.43173E-02
22 +2.84051E-02
23 +3.24604E-02
24 +3.64143E-02
25 +4.01987E-02
26 +4.37450E-02
27 +4.69873E-02
28 +4.98573E-02
29 +5.22796E-02
30 +5.41140E-02
31 +5.43903E-02

3
FIR_QDP380900616S1CCOUNTS - Digital Counts
COUNTS - Digital Counts
32+-----------------------------------+|
Decimation||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Input sample rate (HZ):
Decimation factor:
Decimation offset:
Estimated delay (seconds):
Correction applied (seconds):

3
5.1200E+03
00016
00000
+6.1520E-03+6.2500E-03+-----------------------------------+|
Channel Sensitivity/Gain||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Sensitivity:
Frequency of sensitivity:
Number of calibrations:3+1.01477E+00+0.00000E+00
0+-----------------------------------+|FIR Response||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Response Name:
Symmetry Code:Response in units lookup:
Response out units lookup:
Number of Coefficients:
i FIR Coefficient
0 +1.50487E-04
1 +3.05924E-04
2 +4.42949E-04
3 +3.87117E-04
4 -4.73787E-05
5 -9.70772E-04
6 -2.30317E-03
7 -3.70638E-03
8 -4.62505E-03
9 -4.46480E-03
10 -2.86984E-03
11 +7.00861E-06
12 +3.38520E-03

4
FIR_QDP380900616S2C
COUNTS - Digital Counts
COUNTS - Digital Counts
36

92 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35

+6.00353E-03+6.55094E-03+4.25995E-03-5.76024E-04-6.43416E-03-1.09214E-02-1.16364E-02-7.26515E-03+1.53727E-03+1.19331E-02+1.96157E-02+2.03516E-02+1.18680E-02-4.64369E-03-2.41125E-02-3.86383E-02-3.98499E-02-2.18684E-02+1.61612E-02+6.89624E-02+1.26003E-01+1.74229E-01+2.01834E-01

Chapter 6

B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
#
#
#
#
#
#
#
B057F03
B057F04
B057F05
B057F06
B057F07
B057F08
#
#
#
#
#
#
#
B058F03
B058F04
B058F05
B058F06
#
#
#
#
#
#
#
B061F03
B061F04
B061F05
B061F06
B061F07
B061F08#
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09

S+-----------------------------------+|
Decimation||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Input sample rate (HZ):
Decimation factor:
Decimation offset:
Estimated delay (seconds):
Correction applied (seconds):

4
3.2000E+02
00004
00000
+9.8611E-02+1.0000E-01+-----------------------------------+|
Channel Sensitivity/Gain||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Sensitivity:
Frequency of sensitivity:
Number of calibrations:4+9.78112E-01+0.00000E+00
0+-----------------------------------+|FIR Response||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Response Name:
Symmetry Code:Response in units lookup:
Response out units lookup:
Number of Coefficients:
i FIR Coefficient
0 +2.88050E-04
1 +1.55314E-03
2 +2.98231E-03
3 +2.51714E-03
4 -5.02927E-04
5 -2.81206E-03
6 -8.08708E-04
7 +3.21543E-03
8 +2.71266E-03
9 -2.91550E-03
10 -5.09429E-03
11 +1.33933E-03
12 +7.40034E-03
13 +1.82797E-03
14 -8.81958E-03
15 -6.56719E-03
16 +8.38609E-03
17 +1.24269E-02
18 -5.12979E-03
19 -1.84869E-02
20 -1.79237E-03
21 +2.33604E-02
22 +1.30477E-02
23 -2.51709E-02
24 -2.93135E-02
25 +2.12669E-02
26 +5.21899E-02
27 -6.61517E-03
28 -8.83535E-02

5FIR_QDP380900616S3C
COUNTS - Digital Counts
COUNTS - Digital Counts
32Standard for the Exchange of Earthquake Data - Reference Manual • 93

Chapter 6 • Station Control Headers
B061F09
B061F09
B061F09
#
#
#
#
#
#
#
B057F03
B057F04
B057F05
B057F06
B057F07
B057F08
#
#
#
#
#
#
#
B058F03
B058F04
B058F05
B058F06
#
#
#
#
#
#
#
B061F03
B061F04
B061F05
B061F06
B061F07
B061F08#
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
#
#
#
#
#
#
#
B057F03
B057F04
B057F05
B057F06
B057F07
B057F08
#
#
#
#

29
30
31

-3.66062E-02+1.86273E-01+4.03764E-01+-----------------------------------+|
Decimation||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+

Stage sequence number:
Input sample rate (HZ):
Decimation factor:
Decimation offset:
Estimated delay (seconds):
Correction applied (seconds):

58.0000E+01
00002
00000
+3.9375E-01+4.0000E-01+-----------------------------------+|
Channel Sensitivity/Gain||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Sensitivity:
Frequency of sensitivity:
Number of calibrations:5+1.01113E+00+0.00000E+00
0+-----------------------------------+|FIR Response||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Response Name:
Symmetry Code:Response in units lookup:
Response out units lookup:
Number of Coefficients:
i FIR Coefficient
0 +2.88050E-04
1 +1.55314E-03
2 +2.98231E-03
3 +2.51714E-03
4 -5.02927E-04
5 -2.81206E-03
6 -8.08708E-04
7 +3.21543E-03
8 +2.71266E-03
9 -2.91550E-03
10 -5.09429E-03
11 +1.33933E-03
12 +7.40034E-03
13 +1.82797E-03
14 -8.81958E-03
15 -6.56719E-03
16 +8.38609E-03
17 +1.24269E-02
18 -5.12979E-03
19 -1.84869E-02
20 -1.79237E-03
21 +2.33604E-02
22 +1.30477E-02
23 -2.51709E-02
24 -2.93135E-02
25 +2.12669E-02
26 +5.21899E-02
27 -6.61517E-03
28 -8.83535E-02
29 -3.66062E-02
30 +1.86273E-01
31 +4.03764E-01

6
FIR_QDP380900616S4C
COUNTS - Digital Counts
COUNTS - Digital Counts
32+-----------------------------------+|
Decimation||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Input sample rate (HZ):
Decimation factor:
Decimation offset:
Estimated delay (seconds):
Correction applied (seconds):

6
4.0000E+01
00002
00000
+7.8750E-01+8.0000E-01+-----------------------------------+|
Channel Sensitivity/Gain||
BK CMBLKS|

94 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control Headers|
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Sensitivity:
Frequency of sensitivity:
Number of calibrations:6+1.01113E+00+0.00000E+00
0+-----------------------------------+|FIR Response||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Response Name:
Symmetry Code:Response in units lookup:
Response out units lookup:
Number of Coefficients:
i FIR Coefficient
0 +2.88050E-04
1 +1.55314E-03
2 +2.98231E-03
3 +2.51714E-03
4 -5.02927E-04
5 -2.81206E-03
6 -8.08708E-04
7 +3.21543E-03
8 +2.71266E-03
9 -2.91550E-03
10 -5.09429E-03
11 +1.33933E-03
12 +7.40034E-03
13 +1.82797E-03
14 -8.81958E-03
15 -6.56719E-03
16 +8.38609E-03
17 +1.24269E-02
18 -5.12979E-03
19 -1.84869E-02
20 -1.79237E-03
21 +2.33604E-02
22 +1.30477E-02
23 -2.51709E-02
24 -2.93135E-02
25 +2.12669E-02
26 +5.21899E-02
27 -6.61517E-03
28 -8.83535E-02
29 -3.66062E-02
30 +1.86273E-01
31 +4.03764E-01

7
FIR_QDP380900616S5C
COUNTS - Digital Counts
COUNTS - Digital Counts
32S+-----------------------------------+|
Decimation||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Input sample rate (HZ):
Decimation factor:
Decimation offset:
Estimated delay (seconds):
Correction applied (seconds):

7
2.0000E+01
00002
00000
+1.5750E+00+1.6000E+00+-----------------------------------+|
Channel Sensitivity/Gain||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Sensitivity:
Frequency of sensitivity:
Number of calibrations:7+1.01113E+00+0.00000E+00
0+-----------------------------------+|FIR Response||
BK CMB
LKS||
06/15/2004 to 12/17/2010|+-----------------------------------+
Stage sequence number:
Response Name:
Symmetry Code:Response in units lookup:
Response out units lookup:
Number of Coefficients:

Chapter 6###
B058F03
B058F04
B058F05
B058F06
#
#
#
#
#
#
#
B061F03
B061F04
B061F05
B061F06
B061F07
B061F08#
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
#
#
#
#
#
#
#
B057F03
B057F04
B057F05
B057F06
B057F07
B057F08
#
#
#
#
#
#
#
B058F03
B058F04
B058F05
B058F06
#
#
#
#
#
#
#
B061F03
B061F04
B061F05
B061F06
B061F07
B061F088
FIR_QDP380900616S6C
COUNTS - Digital Counts
COUNTS - Digital Counts
130Standard for the Exchange of Earthquake Data - Reference Manual • 95

Chapter 6 • Station Control Headers#
B061F09
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B061F09
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B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09
B061F09

0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88

i FIR Coefficient-2.21394E-05-3.84536E-05-4.37853E-05-7.33723E-05-9.14422E-05-1.23938E-04-1.49931E-04-1.82887E-04-2.09854E-04-2.37087E-04-2.56051E-04-2.69086E-04-2.70466E-04-2.60902E-04-2.37020E-04-1.99576E-04-1.47611E-04-8.30789E-05-7.54570E-06+7.52988E-05+1.61596E-04+2.46079E-04+3.23380E-04+3.87565E-04+4.33107E-04+4.54860E-04+4.48836E-04+4.12364E-04+3.44630E-04+2.46817E-04+1.22361E-04-2.31280E-05-1.81951E-04-3.44675E-04-5.00592E-04-6.38366E-04-7.46740E-04-8.15366E-04-8.35627E-04-8.01410E-04-7.09796E-04-5.61590E-04-3.61609E-04-1.18741E-04+1.54300E-04+4.41517E-04+7.24451E-04+9.83255E-04+1.19797E-03+1.34993E-03+1.42318E-03+1.40583E-03+1.29129E-03+1.07915E-03+7.75740E-04+3.94305E-04-4.53973E-05-5.17900E-04-9.93357E-04-1.43926E-03-1.82251E-03-2.11168E-03-2.27934E-03-2.30429E-03-2.17355E-03-1.88392E-03-1.44292E-03-8.69178E-04-1.91919E-04+5.50195E-04+1.31105E-03+2.03971E-03+2.68357E-03+3.19189E-03+3.51943E-03+3.62999E-03+3.49961E-03+3.11909E-03+2.49578E-03+1.65425E-03+6.35925E-04-5.02531E-04-1.69197E-03-2.85453E-03-3.90837E-03-4.77288E-03-5.37430E-03-5.65125E-03-5.55977E-03

96 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 6 • Station Control HeadersStandard for the Exchange of Earthquake Data - Reference Manual • 97

Chapter 6

B061F09
89 -5.07764E-03
B061F0990 -4.20746E-03
B061F0991 -2.97838E-03
B061F0992 -1.44617E-03
B061F09
93 +3.08559E-04
B061F09
94 +2.18377E-03
B061F09
95 +4.06116E-03
B061F09
96 +5.81273E-03
B061F09
97 +7.30847E-03
B061F09
98 +8.42472E-03
B061F09
99 +9.05277E-03
B061F09
100 +9.10711E-03
B061F09
101 +8.53281E-03
B061F09
102 +7.31155E-03
B061F09
103 +5.46583E-03
B061F09
104 +3.06090E-03
B061F09
105 +2.04398E-04
B061F09
106 -2.95676E-03
B061F09
107 -6.24185E-03
B061F09108 -9.44424E-03
B061F09
109 -1.23413E-02
B061F09
110 -1.47056E-02
B061F09
111 -1.63175E-02
B061F09
112 -1.69774E-02
B061F09
113 -1.65182E-02
B061F09
114 -1.48160E-02
B061F09
115 -1.17993E-02
B061F09
116 -7.45577E-03
B061F09
117 -1.83625E-03
B061F09
118 +4.94481E-03
B061F09
119 +1.27119E-02
B061F09
120 +2.12343E-02
B061F09
121 +3.02355E-02
B061F09
122 +3.94042E-02
B061F09
123 +4.84088E-02
B061F09
124 +5.69120E-02
B061F09
125 +6.45869E-02
B061F09
126 +7.11325E-02
B061F09
127 +7.62881E-02
B061F09
128 +7.98460E-02
B061F09
129 +8.16620E-02##+-----------------------------------+#|
Decimation|#|
BK CMB
LKS|#|
06/15/2004 to 12/17/2010|#+-----------------------------------+#
B057F03
Stage sequence number:
8
B057F04
Input sample rate (HZ):
1.0000E+01
B057F05
Decimation factor:
00010
B057F06
Decimation offset:
00000
B057F07
Estimated delay (seconds):+1.2950E+02
B057F08
Correction applied (seconds):+1.3000E+02##+-----------------------------------+#|
Channel Sensitivity/Gain|#|
BK CMB
LKS|#|
06/15/2004 to 12/17/2010|#+-----------------------------------+#
B058F03
Stage sequence number:
8
B058F04
Sensitivity:+9.96712E-01
B058F05
Frequency of sensitivity:+0.00000E+00
B058F06
Number of calibrations:0##+-----------------------------------+#|
Response (Polynomial)|#|
BK CMB
LKS|#|
06/15/2004 to 12/17/2010|#+-----------------------------------+#
B062F03
Transfer function type:P
B062F04
Stage sequence number:
0B062F05
Response in units lookup:
C - Degrees Centigrade
B062F06
Response out units lookup:
COUNTS - Digital Counts
B062F07
Polynomial Approximation Type:M
B062F08
Valid Frequency Units:
B
B062F09
Lower Valid Frequency Bound:+0.00000E+00
B062F10Upper Valid Frequency Bound:+1.60000E-02
B062F11Lower Bound of Approximation:+3.40000E+00
B062F12Upper Bound of Approximation:+6.80000E+01
B062F13
Maximum Absolute Error:+1.00000E-01
B062F14
Number of coefficients:
10#
Polynomial coefficients:#
i, coefficient, error
B062F15-16
0 +1.25091E+01 +0.00000E+00
B062F15-16
1 +3.27742E-05 +0.00000E+00
B062F15-16
2 +2.41146E-11 +0.00000E+00
B062F15-16
3 +1.90259E-17 +0.00000E+00

SChapter 6 • Station Control Headers
B062F15-16
B062F15-16
B062F15-16
B062F15-16
B062F15-16
B062F15-16

4
5
6
7
8
9

+2.58585E-23+5.44649E-29+7.15752E-35+4.98323E-41+1.73685E-47+2.39751E-54+0.00000E+00+0.00000E+00+0.00000E+00+0.00000E+00+0.00000E+00+0.00000E+00

98 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 7

Chapter 7

TTime Span
Control Headers

Station oriented and event oriented network volumes use time span headers to index the actual data records. Stations
are recorded sequentially, and within each station the channels are recorded sequentially. Field station recordings do
not use these headers.
For event oriented network volumes, the time span refers to the recording time that begins before and ends after ageophysical event. These events may use blockettes to describe the hypocenter and phase arrivals measured at eachstation.
For station oriented network volumes, the time span refers to a standard interval for the whole volume or for eachday on the volume. Either place a set of time span identification records and index records before the data for eachtime span, or, preferably, place all the time span control headers at the beginning of the volume to increase efficiency
at extracting subsets of data. This latter method, implemented in version 2.1 of SEED, allows a reading program toeasily uncover what data is on the volume and exactly where it is, without having to read through all the data. Because
either method can be used, reading programs should never assume the order, but instead search for the time spancontrol headers at the locations described by the Volume Time Span Index Blockette [12], and search for the data at thelocations described by the Time Span Data Start Index Blockette [73] or the Time Series Index Blockette [74].
Versions 2.1 and later place all time span control headers together, after station control headers, and before data.
Version 2.0 placed time spans together, with each time span consisting first of a time span control header, followed byits data. To allow for upward compatibility, SEED reading programs should be able to read both versions, but SEED
writing programs should always write using the latest version of the format.
Standard for the Exchange of Earthquake Data - Reference Manual • 99

Chapter 7 • Time Span Control Headers

Figure 12: Alternate time Span Header Placements

100 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 7 • Time Span Control Headers[70] Time Span Identifier Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Time Span Identifier Blockette
070
Time Span
Not Applicable
Required
Required

Sample:T

0700054P1989,003,00:00:00.0000~1989,004,00:00:00.0000~

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5

Blockette type — 070
Length of blockette
Time span flag
Beginning time of data span
End time of data span

D
D
A
V
V

3
4
1
1—22
1—22

“###”
“####”
[U]
TIME
TIME

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

Indicates whether the data are for a station network volume’s accounting period or for an event network volume.
E — Data are event oriented
P — Data are for a given period

4

The time when this time span begins.

5

The time when this time span ends.

Chapter 7

Use this blockette to describe the time series—when it starts, when it ends, and whether its data are event oriented ornot.

Standard for the Exchange of Earthquake Data - Reference Manual • 101

Chapter 7 • Time Span Control Headers[71] Hypocenter Information Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Hypocenter Information Blockette
071
Time Span
Not Applicable
Optional
Desirable

Use this blockette to include hypocenter subsidiary information.

V2.3 V2.3 V2.3 -Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7

Blockette type — 071
Length of blockette
Origin time of event
Hypocenter source identifier
Latitude of event (degrees)Longitude of event (degrees)
Depth (Km)

D
D
V
D
D
D
D

3
4
1—22
2
10
11
7

“###”
“####”
TIME“##”“-##.######”“-###.######”“####.##”

8

“##”

9
10
11

Number of magnitudes
D
2
REPEAT fields 9 — 11 for the Number of magnitudes:
MagnitudeD
5
Magnitude typeV
1—10
Magnitude source
D
2

12
13
14

Seismic region
Seismic Location
Region Name“###”“####”[UNLPS]

D
D
V

3
4
1— 40

“##.##”[UNLPS]“##”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3

The event’s origin time.

4

The source quoted for the hypocenter information. Use a source lookup code key that refers to field 3 of the Cited
Source Dictionary Blockette [32], where the source reference is located.

5

The event’s latitude (negative is south).

6

The event’s longitude (negative is west).

7

Depth in kilometers.

8

The number of magnitude listings that follow.

9

The magnitude value.

10

The magnitude type (MB, Msz, etc.)

11

Reference for the magnitude. This field may be set to zero if it is the same as the value in field 4, above. Otherwise,
use a source lookup code key that refers to field 3 of the Cited Source Dictionary Blockette [32], where the source
reference is located.

12

The Flinn-Engdahl seismic geographic region number. This is from a table of numeric codings for general geographic Earth regions. This is a number from (currently) 1 to 50. See Appendix K.

13

The Flinn-Engdahl seismic location number. Refers to Earth place names. This is a number from (currently) 1 to729. See Appendix K.

14

The Flinn-Engdahl standard place name. See Appendix K.

NOTE: For station oriented network volumes, you may include a list of event hypocenters for the time interval, or a list of
manually or automatically determined arrival times.
102 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 7 • Time Span Control Headers[72] Event Phases Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Event Phases Blockette
072
Time Span
Not Applicable
Optional
Desirable

V2.3 V2.3 -Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8
9
10
11
12

Blockette type — 072
Length of blockette
Station identifier
Location identifier
Channel identifier
Arrival time of phase
Amplitude of signal
Period of signal (seconds)
Signal-to-noise ratio
Name of phase
SourceNetwork Code

D
D
A
A
A
V
F
F
F
V
D
A

3
4
5
2
3
1—22
10
10
10
1—20
2
2

“###”
“####”
[UN]
[UN]
[UN]
TIME
“#.####E-##”“#.####E-##”“#.####E-##”[UNLP]“##”[ULN]

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2.

3Standard station identifier.

4Standard location name.

5Standard channel identifier (see Appendix A).

6

Phase arrival time at the station.

7

The amplitude of the pick, usually measured in the same ground motion units as the channel. See field 8 in the
Channel Identifier Blockette [52] for the units of the channel’s ground motion.

8

Signal period.

9

The signal’s signal-to-noise ratio, if known; otherwise, set to 0.0.

10The standard name of the phase. Station event pickers can use the “P” phase.

11

Reference for source of the phase pick. Refers to blockette [32], field 3.

12

The two character identifier that identifies the network operator. See Appendix J for the current list of Network
Codes.

Standard for the Exchange of Earthquake Data - Reference Manual • 103

Chapter 7

This blockette lists the phase arrivals at the different stations. A large number of these are frequently placed within a
SEED volume.

TChapter 7 • Time Span Control Headers[73] Time Span Data Start Index Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Time Span Data Start Index Blockette
073
Time Span
Not Applicable
Required in V 2.0; superseded by 074 in V 2.1
Required in V 2.0; superseded by 074 in V 2.1

This blockette stores information about the different time series in the time span. There is usually one index entry here foreach time span encountered. (NOTE: This blockette was used by SEED 2.0. Current SEED writing programs should not
use this blockette, but reading programs should allow for it.)Sample:07300710002BJIΔΔΔΔVPE1989,003,00:00:09.4400~00029701ΔΔΔΔΔΔΔΔΔΔ~00030101

Note

Field nameType

Length

Mask or Flags

1
2

Blockette type — 073
Length of blockette

D
D

3
4

“###”
“####”

3

Number of data pieces
D
4
REPEAT fields 4 — 9 for the Number of data pieces:
Station identifier of data pieceA
5
Location identifier
A
2
Channel identifierA
3Time of record
V
1—22
Sequence numberD
6
of first record
Sub-sequence number
D
2

4
5
6
7
8
9

“####”
[UN]
[UN]
[UN]
TIME
“######”“##”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. This blockette may exceed the maximum
length of 9999 bytes when there are time problems at the station or when event pickers are too sensitive. SEED
writing programs should stop the blockette before it reaches 9999 bytes and start on a new one; SEED reading
programs should expect to see multiple blockettes.

3

The number of index entries in the following repeat block.

4Standard station identifier (see Appendix G).

5Standard location identifier.

6Standard channel identifier (see Appendix A).

7

The time when this time series starts (same as the start time for the record).

8

The data sequence number of the data record.

9

The sub-sequence number, used when the data record size is less than the logical record size. Number the first data
record in the logical record “1.”NOTE: Add a trailing record with a blank station and channel, to indicate the record number of the last data record plus
one. SEED needs this done so it can compute the length of the last indexed data segment.

104 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 7 • Time Span Control Headers[74] Time Series Index Blockette
Name:
Blockette Type:
Control Header:
Field Station Volume:
Station Oriented Network Volume:
Event Oriented Network Volume:

Time Series Index Blockette
074
Time Span
Not Applicable
Required
Required

Sample:0740084BJIΔΔΔΔBHZ1992,001,20:18:54.5700~003217011992,001,20:29:36.7200~00322301000CD

Note

Field nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8
9
10

Blockette type — 074
Length of blockette
Station identifier
Location identifier
Channel identifier
Series start time
Sequence number of first data
Sub-sequence number
Series end time
Sequence numberof last record
Sub-sequence number

D
D
A
A
A
V
D
D
V
D

3
4
5
2
3
1—22
6
2
1—22
6

“###”
“####”
[UN]
[UN]
[UN]
TIME
“######”“##”
TIME“######”

D

2

“##”

11

V2.3 -

12
Number of accelerator repeats
D
3
REPEAT fields 13 — 15 for the Number of accelerator repeats:
13
Record start time
V
1—22
14
Sequence number of recordD
615
Sub-sequence number
D
2

“###”

16

[ULN]

Network Code

A

2

TIME
“######”“##”

Notes for fields:
1Standard blockette type identification number.

2

Length of the entire blockette, including the 7 bytes in fields 1 and 2. This blockette may exceed the maximum
length of 9999 bytes when the number of accelerator indices becomes large. SEED writing programs should stop
the blockette before it reaches 9999 bytes and start on a new one; SEED reading programs should expect to see
multiple blockettes.

3Standard station identifier (see Appendix G).

4Standard location identifier.

5Standard channel identifier (see Appendix A).

6

The time when this time series starts (same as the start time for the first record).

7

The sequence number index to the start of the data.
Standard for the Exchange of Earthquake Data - Reference Manual • 105

Chapter 7

This blockette replaces the Time Span Data Start Index Blockette [73], and allows version 2.1 and later of SEED tocorrectly document time tears, events, and time indexes. There should be one Time Series Index Blockette [74] foreach continuous time series and/or each station/ channel combination in the time span. This blockette provides indicesand times of both the beginning and end of the time series described. Writing programs can also provide indices andtimes of intervening records to speed direct access — particularly useful for compressed data.

TChapter 7 • Time Span Control Headers
8

The sub-sequence number, used when the data record size is less than the logical record size. Number the first data
record in the logical record “1.”9The time when this time series ends (same as the end time for the last record).

10

The sequence number index to the last record of the data.

11

The sub-sequence number that refers to the last of the data.

12

The number of accelerator indices in the time series. An accelerator index is an indexed intervening record, placed
somewhere between the start and end of a time series. SEED reading programs use accelerator indices to quickly
access any record in the series: first, these programs use an accelerator index to access the data record; then, they
perform a sequential search of the data records to find the final, target data record. We suggest placing an accelerator index record every 32 records.

13

The start time of the record to which the accelerator index refers.

14

The data record’s sequence number to which the accelerator index refers.

15

The data record’s sub-sequence number to which the accelerator index refers.

16

The two character identifier that identifies the network operator. See Appendix J for the current list of Network
Codes.

NOTE: Accelerator indices are redundant for uncompressed data, because the appropriate record number can be easily
computed.

106 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8

Chapter 8D

Data Records

Each data record in a SEED volume consists of a fixed header, followed by optional data blockettes in the variable
header. These data blockettes are structurally different from control header blockettes: they are mixed-format binary,and they are found only in data records, just after the fixed header. (The control header blockettes listed in the previous
chapters of this reference manual — describing volume, dictionary abbreviation, station, and time span information— are ASCII format only.)

Standard for the Exchange of Earthquake Data - Reference Manual • 107

Chapter 8 • Data Records

Fixed Section of Data Header (48 bytes)
The data record header starts at the first byte. The next eight bytes follow the same structure as the control headers. Byte
seven contains a data quality indicator character. (The eighth byte, or third field, is always an ASCII space — shown
here as a “Δ”). The next ten bytes contain the station, location, and channel identity of the record. The rest of the header
section is binary.
Note

Field nameType

Length

Mask or Flags

1
2

D
A

6
1

“######”

3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18

Sequence number
Data header/quality indicator(“D”|“R”|“Q”|“M”)
Reserved byte (“Δ”)
Station identifier code
Location identifier
Channel identifier
Network CodeRecord start time
Number of samples
Sample rate factor
Sample rate multiplier
Activity flags
I/O and clock flags
Data quality flags
Number of blockettes that follow
Time correction
Beginning of data
First blockette

A
A
A
A
A
B
B
B
B
B
B
B
B
B
B
B

1
5
2
3
2
10
2
2
2
1
1
1
1
4
2
2

Notes for fields:* indicates mandatory information

V2.4 -

V2.3 -

[UN]
[UN]
[UN]
[ULN]

1

* Data record sequence number (Format “######”).

2* “D” or “R” or “Q” or “M” — Data header/quality indicator. Previously, this field was only allowed to be “D”
and was only used to indicate that this is a data header. As of SEED version 2.4 the meaning of this field has been
extended to also indicate the level of quality control that has been applied to the record.
D — The state of quality control of the data is indeterminate.
R — Raw Waveform Data with no Quality Control
Q — Quality Controlled Data, some processes have been applied to the data.
M — Data center modified, time-series values have not been changed.

3Space (ASCII 32) — Reserved; do not use this byte.

4* Station identifier designation (see Appendix G). Left justify and pad with spaces.

5* Location identifier designation. Left justify and pad with spaces.

6* Channel identifier designation (see Appendix A). Left justify and pad with spaces.

7* A two character alphanumeric identifier that uniquely identifies the network operator responsible for the datalogger. This identifier is assigned by the IRIS Data Management Center in consultation with the FDSN working
group on the SEED format.

8* BTIME: Start time of record.

9* UWORD: Number of samples in record.

10* WORD: Sample rate factor:> 0 — Samples/second< 0 — Seconds/sample= 0 — Seconds/sample Use this for ASCII/OPAQUE DATA records (see Blockette 2000 description)
108 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records
11*

WORD: Sample rate multiplier:>0 — Multiplication factor<0 — Division factor

12

UBYTE: Activity flags:*[Bit 0] —[Bit 1] —[Bit 5] —[Bit 6] —13

UBYTE: I/O flags and clock flags:[Bit 0] —Station volume parity error possibly present[Bit 1] —Long record read (possibly no problem)[Bit 3] —Start of time series[Bit 4] —End of time series[Bit 2] —[Bit 5] —14

A negative leap second happened during this record (A 59 second minute). A negative
leap second clock correction has not yet been used, but the U.S. National Bureau ofStandards has said that it might be necessary someday.
Event in progress

Short record read (record padded)

Clock locked

UBYTE: Data quality flags[Bit 0] —Amplifier saturation detected (station dependent)[Bit 1] —Digitizer clipping detected[Bit 3] —Glitches detected[Bit 5] —Telemetry synchronization error[Bit 2] —[Bit 4] —[Bit 6] —[Bit 7] —Spikes detected

Missing/padded data present

A digital filter may be charging
Time tag is questionable

15* UBYTE: Total number of blockettes that follow.

16* LONG: Time correction. This field contains a value that may modify the field 8 record start time. Dependingon the setting of bit 1 in field 12, the record start time may have already been adjusted. The units are in 0.0001
seconds.

17* UWORD: Offset in bytes to the beginning of data. The first byte of the data records is byte 0.

18* UWORD: Offset in bytes to the first data blockette in this data record. Enter 0 if there are no data blockettes.
The first byte in the data record is byte offset 0.

NOTE: All unused bits in the flag bytes are reserved and must be set to zero.
The last word defines the length of the fixed header. The next-to-last word fixes the length reserved for the entire
header.

Standard for the Exchange of Earthquake Data - Reference Manual • 109

Chapter 8[Bit 2] —[Bit 3] —[Bit 4] —Calibration signals present
Time correction applied. Set this bit to 1 if the time correction in field 16 has been applied to field 8. Set this bit to 0 if the time correction in field 16 has not been applied tofield 8.
Beginning of an event, station trigger
End of the event, station detriggers
A positive leap second happened during this record (A 61 second minute).

DChapter 8 • Data Records
If glitches (missing samples) are detected, set bit 3 of the data quality flags, and code missing data values as the largest
possible value. Do this for any data format, even if you are using the Steim Compression algorithm.
Here is an algorithm and some sample rate combinations that describe how the sample rate factors and multipliers work:
If Sample rate factor > 0 and Sample rate Multiplier > 0,
Then nominal Sample rate = Sample rate factor X Sample rate multiplier
If Sample rate factor > 0 and Sample rate Multiplier < 0,Then nominal Sample rate = -1 X Sample rate factor / Sample rate multiplier
If Sample rate factor < 0 and Sample rate Multiplier > 0,
Then nominal Sample rate = -1 X Sample rate multiplier / Sample rate factor
If Sample rate factor < 0 and Sample rate Multiplier < 0,Then nominal Sample rate = 1/ (Sample rate factor X Sample rate multiplier)Sample rate

Sample rate factor

Sample rate multiplier

330 SPS

33
330

10
1

330.6 SPS

3306

-10

1 SP Min-60

1

0.1 SPS

1
-10
-1

-10
1
-10

110 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records[100] Sample Rate Blockette (12 bytes)
V 2.3 – Introduced in SEED Version 2.3
Field nameType

Length123
45

Blockette type — 100
Next blockette’s byte number
Actual Sample Rate
Flags (to be defined)
Reserved byte

B
B
B
B
B

2
2
4
1
3

Mask or Flags

Notes for fields:
1

UWORD: Blockette type (100): sample rate.

2

UWORD: Byte number of next blockette. (Calculate this as the byte offset from the beginning of the logicalrecord — including the fixed section of the data header; use 0 if no more blockettes will follow.)

3

FLOAT: Actual sample rate of this data block.

4

BYTE: Flags (to be defined)

5

UBYTE: Reserved; do not use.

Standard for the Exchange of Earthquake Data - Reference Manual • 111

Chapter 8

NoteDChapter 8 • Data Records[200] Generic Event Detection Blockette (52 bytes)
Note

Field nameType

Length

1
2
3
4
5
6
7
8
9

Blockette type — 200
Next blockette’s byte number
Signal amplitude
Signal period
Background estimate
Event detection flags
Reserved byte
Signal onset time
Detector Name

B
B
B
B
B
B
B
B
A

2
2
4
4
4
1
1
10
24

Mask or Flags

Notes for fields:
1

UWORD: Blockette type [200]: event detection information.

2

UWORD: Byte number of next blockette. (Calculate this as the byte offset from the beginning of the logical record— including the fixed section of the data header; use 0 if no more blockettes will follow.)

3

FLOAT: Amplitude of signal (for units, see event detection flags, below; 0 if unknown).

4

FLOAT: Period of signal, in seconds (0 if unknown).

5

FLOAT: Background estimate (for units, see event detection flags, below; 0 if unknown).

6

UBYTE: Event detection flags:[Bit 0] — If set: dilatation wave; if unset: compression[Bit 1] — If set: units above are after deconvolution(see Channel Identifier Blockette [52], field 8); if unset: digital counts[Bit 2] — When set, bit 0 is undetermined[Other bits reserved and must be zero.]

7

UBYTE: Reserved; do not use.

8

BTIME: Time of the onset of the signal.

9

CHAR*24: The name of the event detector.

112 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records[201] Murdock Event Detection Blockette (60 bytes)
Field nameType

Length

1
2
3
4
5
6
7
8
9
10
11
12

Blockette type — 201
Next blockette’s byte number
Signal amplitude
Signal period
Background estimate
Event detection flags
Reserved byte
Signal onset time
Signal-to-noise ratio values
Lookback value
Pick algorithm
Detector name

B
B
B
B
B
B
B
B
B
B
B
A

2
2
4
4
4
1
1
10
6
1
1
24

Mask or Flags

Notes for fields:
1

UWORD: Blockette type [201]: event detection information.

2

UWORD: Byte number of next blockette (0 if no more).

3

FLOAT: Amplitude of signal (in counts).

4

FLOAT: Period of signal (in seconds).

5

FLOAT: Background estimate (in counts).

6

UBYTE: Event detection flags:[Bit 0] — If set: dilatation wave; if unset: compression[Other bits reserved and must be zero.]

7

UBYTE: Reserved; do not use.

8

BTIME: Onset time of the signal.

9

UBYTE*6: Signal-to-noise ratio values.

10

UBYTE: Lookback value (0,1,2).

11

UBYTE: Pick algorithm (0,1).

12

CHAR*24: The name of the event detector.

NOTE: See Murdock (1983) and Murdock (1987) for more information on this type of event detector, and on what thefields listed above should contain.

Standard for the Exchange of Earthquake Data - Reference Manual • 113

Chapter 8

NoteDChapter 8 • Data Records[202] Log-Z Event Detection Blockette (reserved)
See Blandford (1981) for more information on this type of event detector. As of this printing, no blockette layout for thisdetector has been created.

114 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records[300] Step Calibration Blockette (60 bytes)
Field nameType

Length

1
2
3
4
5
6
7
8
9
10
11
12
13

Blockette type — 300
Next blockette’s byte number
Beginning of calibration time
Number of step calibrations
Calibration flags
Step duration
Interval duration
Calibration signal amplitude
Channel with calibration input
Reserved byte
Reference amplitude
Coupling
Rolloff

B
B
B
B
B
B
B
B
A
B
B
A
A

2
2
10
1
1
4
4
4
3
1
4
12
12

Mask or Flags

Notes for fields:
1

UWORD: Blockette type [300]: step calibration.

2

UWORD: Byte number of next blockette (0 if no more).

3

BTIME: Beginning time of calibration.

4

UBYTE: Number of step calibrations in sequence.

5

UBYTE : Calibration flags:			[Bit 0] — If set: first pulse is positive			[Bit 1] — If set: calibration’s alternate sign			[Bit 2] — If set: calibration was automatic; if unset: manual			[Bit 3] — If set: calibration continued from previous record(s)			[Other bits reserved and must be zero.]6

ULONG: Number of .0001 second ticks for the duration of the step.

7

ULONG: Number of .0001 second ticks for the interval between times the calibration step is “on.”8

FLOAT: Amplitude of calibration signal in units (see Channel Identifier Blockette [52], field 9).

9CHAR*3: Channel containing calibration input (blank means none). SEED assumes that the calibration output
is on the current channel, identified in the fixed header.

10

UBYTE: Reserved; do not use.

11

ULONG: Reference amplitude. This is a user defined value that indicates either the voltage or amperage ofthe calibration signal when the calibrator is set to 0dB. If this value is zero, then no units are specified, and theamplitude (Note 4) will be reported in “binary decibels” from 0 to -96.

12

CHAR*12: Coupling of calibration signal, such as “Resistive “ or “Capacitive”.

13

CHAR*12: Rolloff characteristics for any filters used on the calibrator, such as “3dB@10Hz”.

Standard for the Exchange of Earthquake Data - Reference Manual • 115

Chapter 8

NoteDChapter 8 • Data Records[310] Sine Calibration Blockette (60 bytes)
Note

Field nameType

Length

1
2
3
4
5
6
7
8
9
10
11
12
13

Blockette type — 310
Next blockette’s byte number
Beginning of calibration time
Reserved byte
Calibration flags
Calibration duration
Period of signal (seconds)
Amplitude of signal
Channel with calibration input
Reserved byte
Reference amplitude
Coupling
Rolloff

B
B
B
B
B
B
B
B
A
B
B
A
A

2
2
10
1
1
4
4
4
3
1
4
12
12

Mask or Flags

Notes for fields:
1

UWORD: Blockette type [310]: sine calibration.

2

UWORD: Byte number of next blockette (0 if no more).

3

BTIME: Beginning time of calibration.

4

UBYTE: Reserved; do not use.

5

UBYTE : Calibration flags:			[Bit 2] — If set: calibration was automatic; otherwise: manual			[Bit 3] — If set: calibration continued from previous record(s)			[Bit 4] — If set: peak-to-peak amplitude

			[Bit 5] — If set: zero-to-peak amplitude

			[Bit 6] — If set: RMS amplitude			[Other bits reserved and must be zero.]6

ULONG: Number of .0001 second ticks for the duration of calibration.

7

FLOAT: Period of signal in seconds.

8

FLOAT: Amplitude of signal in units (see Channel Identifier Blockette [52), field 9).

9CHAR*3: Channel containing calibration input (blank means none).

10

UBYTE: Reserved; do not use.

11

ULONG: Reference amplitude. This is a user defined value that indicates either the voltage or amperage of the calibration signal when the calibrator is set to 0dB. If this value is zero, then no units are specified, and the amplitude(Note 4) will be reported in “binary decibels” from 0 to -96.

12

CHAR*12: Coupling of calibration signal such as “Resistive or “Capacitive”.

13

CHAR*12: Rolloff characteristics for any filters used on the calibration, such as “3dB@10Hz”.

NOTE: Only one of flag bits 4, 5, and 6 can be set at one time, but one of them must be set.

116 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records[320] Pseudo-random Calibration Blockette (64 bytes)
Field nameType

Length

1
2
3
4
5
6
7
8
9
10
11
12
13

Blockette type — 320
Next blockette’s byte number
Beginning of calibration time
Reserved byte
Calibration flags
Calibration duration
Peak-to-peak amplitude of steps
Channel with calibration input
Reserved byte
Reference amplitude
Coupling
Rolloff
Noise type

B
B
B
B
B
B
B
A
B
B
A
A
A

2
2
10
1
1
4
4
3
1
4
12
12
8

Mask or Flags

Notes for fields:
1

UWORD: Blockette type [320]: pseudo-random binary sequence.

2

UWORD: Byte number of next blockette (0 if no more).

3

BTIME: Beginning time of calibration.

4

UBYTE: Reserved; do not use.

5

UBYTE : Calibration flags:			[Bit 2] — If set: calibration was automatic; otherwise: manual			[Bit 3] — If set: calibration continued from previous record(s)			[Bit 4] — If set: random amplitudes

			(must have a calibration in channel)			[Other bits reserved and must be zero.]6

ULONG: Number of .0001 second ticks for the duration of calibration.

7

FLOAT: Peak-to-peak amplitude of steps in units (see Channel Identifier Blockette [52], field 9).

8

CHAR*3: Channel containing calibration input (blank if none).

9

UBYTE: Reserved; do not use.

10

ULONG: Reference amplitude. This is a user defined value that indicates either the voltage or amperage ofthe calibration signal when the calibrator is set to 0dB. If this value is zero, then no units are specified, and theamplitude (Note 4) will be reported in “binary decibels” from 0 to -96.

11

CHAR*12: Coupling of calibration signal such as “Resistive or “Capacitive”.

12

CHAR*12: Rolloff characteristics for any filters used on the calibration, such as “3dB@10Hz”.

13

CHAR*8: Noise characteristics, such as “White” or “Red”.

NOTE: When you set calibration flag bit 4, the amplitude value contains the maximum peak- to-peak amplitude.

Standard for the Exchange of Earthquake Data - Reference Manual • 117

Chapter 8

NoteDChapter 8 • Data Records[390] Generic Calibration Blockette (28 bytes)
Note

Field nameType

Length

1
2
3
4
5
6
7
8
9

Blockette type — 390
Next blockette’s byte number
Beginning of calibration time
Reserved byte
Calibration flags
Calibration duration
Calibration signal amplitude
Channel with calibration input
Reserved byte

B
B
B
B
B
B
B
A
B

2
2
10
1
1
4
4
3
1

Mask or Flags

Notes for fields:
1

UWORD: Blockette type [390]: generic calibration.

2

UWORD: Byte number of next blockette (0 if no more).

3

BTIME: Beginning time of calibration.

4

UBYTE: Reserved; do not use.

5

UBYTE: Calibration flags:			[Bit 2] — If set: calibration was automatic; otherwise: manual			[Bit 3] — If set: calibration continued from previous record(s)			[Other bits reserved and must be zero.]6

ULONG: Number of .0001 second ticks for the duration of calibration.

7

FLOAT: Amplitude of calibration in units, if known (see Channel Identifier Blockette [52], field 9).

8

CHAR*3: Channel containing calibration input (must be specified).

9

UBYTE: Reserved; do not use.

118 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records[395] Calibration Abort Blockette (16 bytes)
Note

Field nameType

Length1
2
3
4

Blockette type — 395
Next blockette’s byte number
End of calibration time
Reserved bytes

B
B
B
B

2
2
10
2

Mask or Flags

1

UWORD: Blockette type [395]: calibration abort.

2

UWORD: Byte number of next blockette (0 if no more).

3

BTIME: Time calibration ends.

4

UWORD: Reserved; do not use.

Chapter 8

Notes for fields:

DStandard for the Exchange of Earthquake Data - Reference Manual • 119

Chapter 8 • Data Records[400] Beam Blockette (16 bytes)
Note

Field nameType

Length

1
2
3
4
5
6

Blockette type — 400
Next blockette’s byte number
Beam azimuth (degrees)
Beam slowness (sec/degree)
Beam configuration
Reserved bytes

B
B
B
B
B
B

2
2
4
4
2
2

Mask or Flags

This blockette is used to specify how the beam indicated by the corresponding Beam Configuration Blockette [35] wasformed for this data record. For beams formed by non-plane waves, the Beam Delay Blockette [405] should be used todetermine the beam delay for each component referred to in the Beam Configuration Blockette [35].
Notes for fields:
1

UWORD: Blockette type [400]: beam forming.

2

UWORD: Byte number of next blockette (0 if no more).

3

FLOAT: Azimuth of beam (degrees clockwise from north).

4

FLOAT: Beam slowness (sec/degree).

5

UWORD: Beam configuration (see field 3 of the Beam Configuration Blockette [35] abbreviation dictionary).
NOTE: This field is a binary equivalent of the ASCII formatted dictionary key entry number in the Beam
Configuration Blockette [35]. This is the only place in SEED Version 2.1 where this “ASCII-to-binary” conversion
needs to be made.

6

UWORD: Reserved; do not use.

120 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records[405] Beam Delay Blockette (6 bytes)
Use this blockette to define beams that do not travel as plane waves at constant velocities across arrays. This blockette,
if used, will always follow a Beam Blockette [400]. The Beam Delay Blockette [405] describes the delay for each input
component in the samples. SEED reading programs must find a corresponding entry in the Beam Delay Blockette[405] for each component in the Beam Configuration Blockette [35] of the abbreviation dictionary control headers,indexed by the Beam Blockette [400].

Field nameType

Length1
2
3

Blockette type — 405
Next blockette’s byte number
Array of delay values

B
B
B

2
2
2

Mask or Flags

Notes for fields:
1

UWORD: Blockette type [405]: beam delay.

2

UWORD: Byte number of next blockette (0 if no more).

3

UWORD: Array of delay values (one for each entry of the Beam Configuration Blockette [35]. The array values
are in .0001 second ticks.

Standard for the Exchange of Earthquake Data - Reference Manual • 121

Chapter 8

NoteDChapter 8 • Data Records[500] Timing Blockette (200 bytes)
Note

Field nameType

Length

1
2
3
4
5
6
7
8
9
10

Blockette type — 500
Next blockette offset
VCO correction
Time of exceptionµsec
Reception Quality
Exception countException type
Clock model
Clock status

B
B
B
B
B
B
B
A
A
A

2
2
4
10
1
1
4
16
32
128

Mask or Flags

Notes for fields:
1

UWORD : Blockette type [500]: Timing blockette.

2

UWORD : Byte number of next blockette (0 if no more).

3

FLOAT: VCO correction is a floating point percentage from 0.0 to 100.0% of VCO control value, where 0.0 is
slowest , and 100.0% is fastest.

4

BTIME: Time of exception, same format as record start time.

5

BYTE: µsec has the clock time down to the microsecond. The SEED format handles down to 100µsecs. This field
is an offset from that value. The recommended value is from -50 to +49 µsecs. At the users option, this value may
be from 0 to +99 µsecs.

6

UBYTE: Reception quality is a number from 0 to 100% of maximum clock accuracy based only on informationfrom the clock.

7

ULONG: Exception count is an integer count, with its meaning based on the type of exception, such as 15 missing
timemarks.

8

CHAR*16: Exception type describes the type of clock exception, such as “Missing” or “Unexpected”.

9

CHAR*32: Clock model is an optional description of the clock, such as “Quanterra GPS1/QTS”.

10

CHAR*128: Clock status is an optional description of clock specific parameters, such as the station for an Omega
clock, or satellite signal to noise ratios for GPS clocks.

122 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records[1000] Data Only SEED Blockette (8 bytes)
V 2.3 – Introduced in SEED Version 2.3
Field nameType

Length

1
2
3
4
5
6

Blockette type — 1000
Next blockette’s byte number
Encoding Format
Word order
Data Record Length
Reserved

B
B
B
B
B
B

2
2
1
1
1
1

Mask or Flags

Notes for fields:

Chapter 8

Note

1

UWORD : Blockette type (1000): Data Only SEEDD

2

UWORD : Byte number of next blockette. (Calculate this as the byte offset from the beginning of the logicalrecord - including the fixed section of the data header; use 0 if no more blockettes will follow.)

3

BYTE : A code indicating the encoding format. This number is assigned by the FDSN Data Exchange Working
Group. To request that a new format be included contact the FDSN through the FDSN Archive at the IRIS DataManagement Center. To be supported in Data Only SEED, the data format must be expressible in SEED DDL. A
list of valid codes at the time of publication follows.
CODES 0-9
0
1
2
3
4
5

GENERALASCII text, byte order as specified in field 4
16 bit integers
24 bit integers
32 bit integers
IEEE floating point
IEEE double precision floating point

CODES 10 - 29
10
11
12
13
14
15
16
17
18
19

FDSN Networks
STEIM (1) Compression
STEIM (2) Compression
GEOSCOPE Multiplexed Format 24 bit integer
GEOSCOPE Multiplexed Format 16 bit gain ranged, 3 bit exponent
GEOSCOPE Multiplexed Format 16 bit gain ranged, 4 bit exponent
US National Network compression
CDSN 16 bit gain ranged
Graefenberg 16 bit gain ranged
IPG - Strasbourg 16 bit gain ranged
STEIM (3) Compression

CODES 30 - 39
30
31
32
33

OLDER NETWORKSSRO Format
HGLP Format
DWWSSN Gain Ranged Format
RSTN 16 bit gain ranged

4

The byte swapping order for 16 bit and 32 bit words. A 0 indicates little-endian order and a 1 indicates big-endian
word order. See fields 11 and 12 of blockette 50.

5

The exponent (as a power of two) of the record length for these data. The data record can be as small as 256 bytes
and, in Data Only SEED format as large as 2 raised to the 256 power.

Standard for the Exchange of Earthquake Data - Reference Manual • 123

Chapter 8 • Data Records[1001] Data Extension Blockette (8 bytes)
V 2.3 – Introduced in SEED Version 2.3
Note

Field nameType

Length

1
2
3
4
5
6

Blockette type — 1001
Next blockette’s byte number
Timing qualityµsec
Reserved
Frame count

B
B
B
B
B
B

2
2
1
1
1
1

Mask or Flags

Notes for fields:
1

UWORD: Blockette type [1001]: Data extension blockette

2

UWORD: Byte number of next blockette.

3

UBYTE: Timing quality is a vendor specific value from 0 to 100% of maximum accuracy, taking into account bothclock quality and data flags.

4

BYTE: µsec has the data start time down to the microsecond. The SEED format handles down to 100µsecs. This
field is an offset from that value. The recommended value is from -50 to +49µsecs. At the users option, this value
may be from 0 to +99µsecs.

5

Reserved byte.

6

UBYTE: Frame count is the number of 64 byte compressed data frames in the 4K record (maximum of 63). Note thatthe user may specify fewer than the maximum allowable frames in a 4K record to reduce latency

124 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records[2000] Variable Length Opaque Data Blockette
V 2.3 – Introduced in SEED Version 2.3
Field nameType

LengthOffset

1
2
3
4
5
6
7
8
9

Blockette type — 2000
Next blockette’s byte number
Total blockette length in bytes
Offset to Opaque Data
Record number
Data Word order
Opaque Data flags
Number of Opaque Header fields
Opaque Data Header fields
a Record typeb Vendor typec Model typed Softwaree Firmware
Opaque Data

B
B
B
B
B
B
B
B
V

2
2
2
2
4
1
1
1
V

0
2
4
6
8
12
13
14
15

10

OpaqueMore than one blockette 2000 may be stored in a SEED data record if the SEED data record timetag is not required for
precise timing of the data in the opaque blockette. Under normal usage, there would be no data in the data portion of
the SEED data record. However, it is possible that the blockette 2000 could be used to provide additional information
for a normal timeseries data channel.
Notes for Fields:
1

UWORD: Blockette type (2000): Opaque Data blockette.

2

UWORD: Byte number of next blockette (Calculate this as the byte offset from the beginning of the logicalrecord - including the fixed section of the data header; use 0 if no more blockettes will follow.)3

UWORD: Blockette length. The total number of bytes in this blockette, including the 6 bytes of fields 1, 2, and3. The only restriction is that the blockette must fit within a single SEED data record for the channel. Otherwise,
the blockette must be partitioned into multiple blockettes.

4

UWORD: Offset to Opaque Data. Byte offset from beginning of blockette to Opaque Data.

5

ULONG: Record Number. The record number may be used for sequence identification of stream, record, or fileoriented data. If a record is partitioned into multiple opaque blockettes, each blockette containing a portion of
the record should contain the identical record number. It is strongly recommended that the record number beused to aid in the detection of missing data and in merging data from different telemetry streams. Use 0 if data is
not record oriented, or if record number is not required.

6

UBYTE: Word order of binary opaque data. See field 4 of blockette 1000, and fields 11 and 12 of blockette 50.

		

0 = little-endian.

		

1 = big-endian.

7

UBYTE: Opaque Data flags.

			[bit 0] Opaque blockette orientation.
0 = record oriented.
1 = stream oriented.

			[bit 1] Packaging bit.

Standard for the Exchange of Earthquake Data - Reference Manual • 125

Chapter 8

NoteDChapter 8 • Data Records
0 = Blockette 2000s from multiple SEED data records with different timetags may be packaged intoa single SEED data record. The exact original timetag in each SEED Fixed Data Header is not
required for each blockette 2000.
1= Blockette 2000s from multiple SEED data records with differing timetags may NOT be repackaged into a single SEED data record. Set this bit if the timetag in the SEED Fixed Data Header isrequired to properly interpret the opaque data.
			[bits 2-3] Opaque blockette fragmentation flags.
00 = opaque record identified by record number is completely contained in this opaque blockette.
01 = first opaque blockette for record spanning multiple blockettes.
11 = continuation blockette 2...N-1 of record spanning N blockettes.
10 = final blockette for record spanning N blockettes.

			[bits 4-5] File blockette information.
00 = not file oriented.
01 = first blockette of file.
10 = continuation of file.
11 = last blockette of file.

8

UBYTE: Number of Opaque Header fields. Each opaque header field is a variable length ASCII string, terminatedby the character “~”.

9

VAR: Opaque Data Header string, which contains the ASCII variable length fields. Each field is terminated by a“~”. The definition of the fields may be defined by the originator and receiver, but the following are recommended.
Any of the fields may be empty.

10aRecord Type - name of the type of record (e.g. “GPS”, “GPS MBEN”).

b

Vendor Type - name of equipment vendor (e.g. “ASHTECH”).

c

Model type - model type of equipment (e.g. “Z12”).

dSoftware Version - software version number (e.g. “”).

eFirmware Version - firmware version number (e.g. “1G0C”).

OPAQUE: Opaque Data - bytes of opaque data. Total length of opaque data in bytes isblockette_length - 15 - length (opaque_data_header_string)

126 • Standard for the Exchange of Earthquake Data - Reference ManualChapter 8 • Data Records

The Data Section
The data section of a data record is located at the byte specified in the fixed header, at the beginning of the data.
Programs that write data in the SEED format can place that first byte where appropriate. Data begin after the end of
the last header blockette. Leave a gap of any size between the end of the header and the beginning of the data, but itshould not be large unless you require space to add more blockettes later.

For the Steim compression algorithm, the data start at the first available frame (64 X n bytes) after the end of the header
blockettes. The first and last constant of integration (CI) are placed in the beginning of the data as embedded header
information. See Appendix B for a detailed description of the Steim algorithm and its use with the SEED format.

Standard for the Exchange of Earthquake Data - Reference Manual • 127

Chapter 8

The Channel Identifier Blockette [52] in the control headers will define which format will be present in the record.
This provides a coded reference to an entry in the Data Format Dictionary Blockette [30], which describes the internal
representation of the data in the Standard Data Description Language.

DGlossary

Glossary

Glossary

Abbreviation Dictionary Control Header. A set of control headers that define volume-wide abbreviations, especiallyfor data format descriptions and station channel comments.
Accelerator Index. A periodic index used to locate a specific time segment within a time series.
Auxiliary Information. Supplementary information about a seismic station or a logical volume that may be needed toprocess the raw data completely.
Block Multiplexing. Interspersing data records for different channels. Normally, network volumes require that timeseries data be recorded as a straight sequence of data records for each time span. Some station processors at fieldstations are not capable of this (especially for multiplexed time series data). This means that these processors have towrite, at specific times, data records that contain various time series. Block multiplexed data are the result.
Blockette. A data structure consisting of an identification code, a length specification, and a sequence of related data
fields. Formatted blockettes are used in control headers and unformatted blockettes are used in the header portions ofdata records. Blockettes are strung together in specific sequences to make up much of the SEED format.
Calibration. Also, cal. An operation on equipment such as field station instrumentation which determines the sensitivity of the instrumentation to ground motion.
Calibration Information. Raw data from a calibration signal generator. Some calibration techniques require calibration information to be recorded while the output channels of the instrument is calibrated.
Cascade. The response of a channel may be separated into a series of generalized filter sections. Such a separation
assumes that each section behaves independently. The filter sections may be analog or digital, but one section will
include the response of the instrument itself, making the series “generalized.” To determine the overall response of thecascaded filters, the individual sections are convolved in time.
Standard for the Exchange of Earthquake Data - Reference Manual • 129

Glossary
Channel. Also, station channel. Recorded digitized output that forms a time series from a field station instrument througha particular set of filters.
Concatenate. To string together, one item after another.
Continuous Time Series. Continuously recorded raw data. A continuous time series is arbitrarily divided into a number oftime series, each written into a different time span. Continuous time series appear only on station oriented network volumes.
Control Header. Related auxiliary information, formatted according to rules specifying one of four types, and designed tomake SEED data self defining.
Corner. The point at which the slope of the logarithm of the frequency response curve changes.
Data Field. One item of auxiliary information. Data fields are formatted (ASCII) or unformatted (binary). Formatted data
fields may be of fixed or variable length. Unformatted data fields are always fixed in length.
Data Piece. A time series represented in one or more data records. A data piece contains no time tears, and is therefore
continuous. Time span control headers contain entries that indicate where data pieces are located within the SEED format.
Data Record. A SEED data structure that consists of a data record identification block, a fixed header section, a variable
header section, and a data section. One or more data records make up a logical record. Time series and multiplexed timeseries are written as a sequence of one or more data records.
Data Record Identification Block. A fixed length block of bytes containing a sequence number (usually set to zero), a
format object type flag, and a blockette continuation flag. The first data record identification block in a logical record is thelogical record identification block; its sequence number is never zero.
Data Section. The portion of a data record actually containing time series data.
Dynamic Information. Continuously changing information. All raw data, status, and log information are dynamic.
Event. A part of continuous time series data that is denoted by an algorithm-declared trigger event flag set in the data
header.
Event Oriented Network Volume. A logical volume in which event triggered time series from each station channel areorganized into separate time spans for each event (or perhaps a small number of nearly concurrent events).
Event Triggered Time Series. A recorded time series of finite length, initiated or triggered by some external event. Onlya fraction of the raw data from an event triggered channel is recorded in a number of discrete event triggered time series.
Event triggered time series may appear on network (station oriented) volumes or event (event oriented) volumes.
Event Volume. See: Event Network Volume.
Field Recording Format. The original binary representation of recorded raw data. In most cases, the recording format andthe format in which raw data are originally acquired are identical.
Field Station. A physical site where instruments and recording equipment are located.
Field Station Volume. A logical volume that contains channel data recorded by or transmitted from one field station. It
differs from a station oriented network volume in that its control headers may be incomplete, time series may be block
multiplexed, several of its data structures differ, and data block sizes may vary from channel to channel.
FIR filter. A finite impulse response digital filter.
Fixed Header Section. A SEED data structure that contains unformatted identification and status information that appears
in a fixed sequence at the beginning of every data record.
Format Object. A control header, a time series, or a multiplexed time series. Format objects appear as a sequence of one
or more logical records.
Formatted. Information coded as a character string. A formatted write from a high level computer language will produce
formatted data.
Geophysical Information. Raw data from field station instruments.

130 • Standard for the Exchange of Earthquake Data - Reference ManualGlossary
Header Flushing. When writing a logical volume, you can flush all time series logical records, repeat all control
headers, and resume writing time series data periodically. In effect, this creates a number of logical sub-volumes
within one logical volume. Header flushing provides redundant control header information on station volumes, andsynchronizes the start times of data records for all station channels. SEED preserves channel synchronization on
network volumes, although the redundant headers are discarded.
IIR filter. An infinite impulse response digital filter.
Index. An index to a specific logical record. Indices stored in control headers allow a data user to directly use a logicalrecord, skipping over information not of immediate interest. Time series data may have sub-indices. These represent
data records of interest within the indexed logical records.

Logical Record Identification Block. The identification block of a logical record containing a control header, or the
first data record identification block appearing in a logical record; a fixed length block of bytes containing the absolutesequence number of the logical record within the logical volume, a format object type flag, and a blockette continuation
flag.
Logical Sub-Volume. One of several complete logical volume structures within a station logical volume. Each logicalsub-volume begins with a complete set of control headers.
Logical Volume. One complete data set, usually comprising all raw data and all auxiliary data from a set of stations
during one or more time intervals. One or more logical records make up a logical volume. Use a complete, internallyconsistent implementation of the SEED format to write a logical volume. One or more logical volumes may appear
on one physical volume, but a logical volume may not span more than one physical volume. (Control headers can be
duplicated from one physical volume to another, allowing very large amounts of data to be stored on more than one
physical volume.)
Multiplexed Time Series. More than one time series stored in a sequence of multiplexing frames.
Multiplexing Frame. Raw data samples from more than one channel, taken at nearly the same time and stored one
after the other in a fixed sequence.
Network Volume. See: Station Oriented Network Volume and Event Oriented Network Volume.
One’s Complement. Also: 1’s complement. A means of storing numbers in a computer or on a mass storage device,whereby a negative number is created from its positive counterpart by inverting all the number’s bits.
Physical Record. The amount of data accessed on a computer mass storage device in one input or output (I/O)
operation. Depending on the device, the length of the physical record can be either fixed or variable. Logical records
usually occupy a sequence of one or more physical records, although one physical record may contain several shorter
logical records. Logical records may begin and end within a physical record.
Physical Volume Control Header. Physical volume control information that locates separate logical volumes. This
information is always device- and often operating system-dependent, and may not exist for some devices (particularly
sequential devices). The physical volume control header can be created on some devices under user control, but is notpart of the SEED standard.
Physical Volume. One unit of dismountable computer mass storage media (e.g., a magnetic tape reel). One or more
physical records make up a physical volume.
Raw Data. Data samples in the original field recording format.
Sequence Number. A unique, sequential identifying number given to a data record when it is equal to or larger than alogical record.
State-of-Health Information. Raw data relevant to the operation of the station equipment or the station environment.
Static Information. Information that does not change for long periods of time. Most control header information is
static (comments are not).
Station Channel. See: Channel.
Standard for the Exchange of Earthquake Data - Reference Manual • 131

Glossary

Logical Record. A SEED data structure that can be individually located and that begins with a logical record identification block. A sequence of logical records make up a format object.

Glossary
Station Control Header. Static auxiliary information about one station and all of its channels, particularly station
location and channel transfer function information.
Station Log Information. A station volume’s formatted auxiliary information that describes the station processor’s
status and/or the interactions between station operators and station processors; often printed on a console.
Station Oriented Network Volume. A logical volume in which station channels are organized into arbitrary time spans.
One continuous time series, or a sequence of event triggered time series with time gaps between them (in which no data
were recorded), are included for each entire time span for each station channel.
Station Processor. A dedicated computer system at a digital seismic station. This processor controls the station and canbe reprogrammed as needed. It typically controls digital data acquisition, data buffering, calibration, event detection, data
formatting, local data storage, and data telemetry to a central site.
Station Volume. See: Field Station Volume.
Status Information. Auxiliary information pertaining to a station channel for a particular time interval.
Time Pointer. See: Accelerator index.
Time Series. Raw data from one station channel which have been continuously recorded during a finite time interval.
Time Span Control Header. A SEED data structure that contains information pertaining to a fixed time interval,
including hypocenter and phase arrival time information, as well as indices to time series.
Time Tear. A time gap, greater than an allowed tolerance, in a time series.
Transfer Function. The response of a channel, usually in counts per physical units as a function of frequency. This
response may appear in several ways, the most precise being a complete description of the Laplace transform of the impulse
response of the analog system, cascaded with a complete description of the digitizing and digital filtering performed.
Two’s Complement. Also: 2’s complement. A means of storing numbers in a computer or on a mass storage device,whereby a negative number is created from its positive counterpart by inverting all the number’s bits, and adding 1 to theresult.
Unformatted. Information coded as a sequence of binary data types. Character data mixed with binary data are also
unformatted. An unformatted write from a high level computer language will produce unformatted data.
Variable Header Section. A sequence of optional unformatted blockettes following the fixed header section andpreceding the data section of a data record.
Volume Index Control Header. A control header containing information about a complete logical volume, including
indices to station control headers and time span control headers.

132 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix A

AppendixA

Appendix A: Channel Naming
Contributed by Scott Halbert

Seismologists have used many conventions for naming channels. Usually, these conventions are designed to meet theparticular needs of one network. But general recording systems — such as the various Global Seismographic Network(GSN) systems that can record many channels at high sample rates — create a need for a standard to handle thevariety of instruments that can be recorded. Modern instrumentation and the need for conformity among cooperating
networks have greatly complicated the problem. Sensors are available in narrow band and broadband configurations
with pass bands in very different parts of the spectrum of interest. Each sensor may have several different outputs withdifferent spectral shaping. In addition, station processors often derive several data streams from one sensor channel bydigital filtering. These possibilities require a comprehensive convention. The desire to combine data from cooperating
networks and to search for like channels automatically requires standardization.
The SEED format uses three letters to name seismic channels, and three letters to name weather or environmental
channels. In the following convention, each letter describes one aspect of the instrumentation and its digitization.
SEED does not require this convention, but we recommend it as a usage standard for Federation members to facilitate
data exchange.

Standard for the Exchange of Earthquake Data - Reference Manual • 133

Appendix A

Band CodeThe first letter specifies the general sampling rate and the response band of the instrument. (The “A” code is reserved foradministrative functions such as miscellaneous state of health.)Band code
F
G
D
C
E
S
H
B
M
L
V
U
R
P
T
Q
A
O

Band type
...
...
...
...
Extremely Short Period
Short PeriodHigh Broad Band
Broad BandMid PeriodLong Period
Very Long Period
Ultra Long Period
Extremely Long Period
On the order of 0.1 to 1 day1
On the order of 1 to 10 days1
Greater than 10 days1
Administrative Instrument Channel
Opaque Instrument Channel

Sample rate (Hz)≥ 1000 to < 5000
≥ 1000 to < 5000
≥ 250 to < 1000
≥ 250 to < 1000
≥ 80 to < 250≥ 10 to < 80
≥ 80 to < 250≥ 10 to < 80
> 1 to < 10≈1
≈ 0.1
≈ 0.01≥ 0.0001 to < 0.001≥ 0.00001 to < 0.0001≥ 0.000001 to < 0.00001< 0.000001
variablevariableCorner period (sec)≥ 10 sec< 10 sec< 10 sec≥ 10 sec< 10 sec< 10 sec≥ 10 sec≥ 10 sec

NANA

1. These are approximate values. The sample rate should be used for the correct Band Code.

Instrument Code and Orientation CodeThe second letter specifies the family to which the sensor belongs. In essence, this identifies what is being measured.
Each of these instrument types are detailed in this section.
The third letter in the channel name is the Orientation Code, which provides a way to indicate the directionality of thesensor measurement. This code is sometimes used for a purpose other than direction, which is instrument-specific. Whenorthogonal directions are used, there are traditional orientations of North (N), East (E), and Vertical (Z), as well as otherorientations that can readily be converted to traditional ones. These options are detailed with each instrument type. Use N
or E for the orientation when it is within 5 degrees of north or east. Use 1 or 2 when orientations are more than 5 degrees
from north or east. Put the actual orientation of the sensor in the dip and azimuth fields of blockette 52.
Seismometer:

Measures displacement/velocity/acceleration along a line defined by the dip and azimuth.

Instrument CodeH
High Gain SeismometerL
Low Gain Seismometer
G
Gravimeter
M
Mass Position SeismometerN*
Accelerometer* historically some channels from accelerometers have used instrumentation codesof L and G. The use of N is the FDSN convention as defined in August 2000.
Orientation Code
ZNE
Traditional (Vertical, North-South, East-West) (see 5 degree convention above)
ABC
Triaxial (Along the edges of a cube turned up on a corner)
TR
For formed beams (Transverse, Radial)
123
Orthogonal components but non traditional orientations(see 5 degree convention above)
UVW
Optional components
Dip/Azimuth:
Ground motion vector (reverse dip/azimuth if signal polarity incorrect)
Signal Units:
M, M/S, M/S**2, (for G & M) M/S**2 (usually)
Channel Flags:G
134 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix A
Tilt Meter:

Measures tilt from the horizontal plane. Azimuth is typically N/S or E/W.

Instrument CodeA
Orientation CodeNE
Traditional
Dip/Azimuth:
Ground motion vector (reverse dip/azimuth if signal polarity incorrect)
Signal Units:
Radians
Channel Flags:
G

The orientation and therefore the dip and azimuth would be perpendicular to the measuring beam (lightor metal), which would be along the average travel vector for the fault. Positive/Negative travel would bearbitrary, but would be noted in the dip/azimuth. Another type of Creep Meter involves using a wire that is
stretched across the fault. Changes in wire length are triangulated to form movement vector.
Instrument CodeB
Orientation CodeUnknown
Dip/Azimuth:
Along the fault or wire vector
Signal Units:
M
Channel Flags:
G
Calibration Input: Usually only used for seismometers or other magnetic coil instruments. This signal
monitors the input signal to the coil to be used in response evaluation. Usually tied to a specific instrument.
Sometimes all instruments are calibrated together, sometimes horizontals are done separately from verticals.
Instrument CodeC
Orientation CodeA B C D.
for when there are only a few cal sources for many devices.
Blank if there is only one calibrator at a time or, Match Calibrated Channel (is. Z, N or E)
Pressure:
A barometer, or microbarometer measures pressure. Used to measure the weatherpressure or sometimes for state of health monitoring down hole. This includes infrasonic and hydrophonemeasurements.
Instrument CodeD
Orientation Code
O
I
D
F
H
U
Dip/Azimuth:
Signal Units:
Channel Flags:

OutsideInsideDown Hole
InfrasoundHydrophone
UndergroundNot applicable — Should be zero.
Pa (Pascals)
W or H

Standard for the Exchange of Earthquake Data - Reference Manual • 135

Appendix

Creep Meter:
Measures the absolute movement between two sides of a fault by means of fixing a metal
beam on one side of the fault and measuring its position on the other side. This is also done with light beams.

AAppendix A
Electronic Test Point:
Used to monitor circuitry inside recording system, local power or seismometer.
Usually for power supply voltages, or line voltages.
Instrument CodeE
Orientation code
Designate as desired, make mnemonic as possible, use numbers for test points, etc.
Dip/Azimuth:
Not applicable
Signal Units:
V, A, Hz, Etc.
Channel Flags:
H
Magnetometer:
Measures the magnetic field where the instrument is sitting. They measure the part of the field
vector that is aligned with the measurement coil. Many magnetometers are three axis. The instrument will typicallybe oriented to local magnetic north. The dip and azimuth should describe this in terms of the geographic north.
Example: Local magnetic north is 13 degrees east of north in Albuquerque. So if the magnetometer is pointed
to magnetic north, the azimuth would be + 103 for the E channel. Some magnetometers do not record any
vector quantity associated with the signal, but record the total intensity. So, these would not have any dip/
azimuth.
Instrument CodeF
Orientation Code
ZNE
Magnetic
Signal Units:
T — Teslas
Channel Flags:G
Humidity:
Absolute/Relative measurements of the humidity. Temperature recordings may also beessential for meaningful results.
Instrument CodeI
Orientation CodeO
Outside Environment
I
Inside Building
D
Down Hole
1234
Cabinet Sources
All other letters available for mnemonic source types.
Dip/Azimuth:
Not applicable — Should be zero.
Signal Units:%
Channel Flags:
W
Rotational Sensor: Measures solid-body rotations about an axis, commonly given in “displacement” (radians),velocity (radians/second) or acceleration (radians/second^2).
Instrument CodeJ
High Gain Seismometer
Orientation Code
ZNE
Traditional (Vertical, North-South, East-West)ABC
Triaxial (Along the edges of a cube turned up on a corner)
TR
For formed beams (Transverse, Radial)
123
Orthogonal components but non traditional orientations
UVW
Optional components
Dip/Azimuth:
Axis about which rotation is measured following right-handed rule.
Signal Units:rad, rad/s, rad/s^2 – following right-handed rule
Channel Flags:G

136 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix A
Temperature:

Measurement of the temperature at some location. Typically used for measuring:

1. Weather
2. State of Health- Outside Temperature- Inside recording building- Down hole
- Inside electronics

Water Current:This measurement measures the velocity of water in a given direction. The measurement
may be at depth, within a borehole, or a variety of other locations.
Instrument CodeO
Orientation CodeUnknown
Dip/Azimuth:
Along current direction
Signal Units:
M/S
Channel Flags:
G
Geophone:

Very short period seismometer, with natural frequency 5 - 10 Hz or higher.

Instrument CodeP
Orientation CodeZNE
Dip/Azimuth:
Signal Units:
Channel Flags:

Traditional
Ground Motion Vector (Reverse dip/azimuth if signal polarity incorrect)
M, M/S, M/S
GElectric Potential: Measures the Electric Potential between two points. This is normally done using a highimpedance voltmeter connected to two electrodes driven into the ground. In the case of magnetotelleuric
work, this is one parameter that must be measured.
Instrument CodeQ
Orientation CodeUnknown
Signal Units:
V — Volts
Channel Flags:
GStandard for the Exchange of Earthquake Data - Reference Manual • 137

Appendix

Instrument CodeK
Orientation CodeO
Outside Environment
I
Inside Building
D
Down Hole
1234
Cabinet sources
All other letters available for mnemonic types.
Dip Azimuth:
Not applicable — Should be zero.
Signal Units:
deg C or deg K
Channel Flags:
W or HA

Appendix A
Rainfall:

Measures total rainfall, or an amount per sampling interval.

Instrument CodeR
Orientation CodeUnknown
Dip/Azimuth:
Not applicable — Should be zero.
Signal Units:
M, M/S
Channel Flags:
W
Linear Strain:
One typical application is to build a very sensitive displacement measuring device,typically a long quartz rod. One end is affixed to a wall. On the free end, a pylon from the floor reaches
up to the rod where something measures the position of the pylon on the rod (like a large LVDT).
There are also some interferometry projects that measure distance with lasers. Dip/Azimuth are the line of the
movement being measured. Positive values are obtained when stress/distance increases, negative, when they
decrease.
Instrument CodeS
Orientation CodeZNE
Dip/Azimuth:
Signal Units:
Channel Flags:

Vertical, North-South, East-West
Along axis of instrument
M/M
G

Tide :
Not to be confused with lunar tidal filters or gravimeter output. Tide instruments measure
the depth of the water at the monitoring site.
Instrument CodeT
Orientation CodeZ
Always vertical
Dip/Azimuth:
Always vertical
Signal Units:
M — Relative to sea level or local ocean depth
Channel Flags:

G

Bolometer:
Infrared instrument used to evaluate average cloud cover. Used in astronomy to determine
observability of sky.
Instrument CodeU
Orientation CodeUnknown
Dip/Azimuth:
Not applicable — Should be zero.
Signal Units:
Unknown
Channel Flags:
W
Volumetric Strain: Unknown
Instrument CodeV
Orientation CodeUnknown
Dip/Azimuth:
Not Applicable — Should be zero.
Signal Units:
M**3/M**3
Channel Flags:G
138 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix A
Wind:

Measures the wind vector or velocity. Normal notion of dip and azimuth does not apply.

Wind speed
Wind Direction Vector — Relative to geographic North
Not Applicable — Should be zero.
W

Derived or Generated Channel:
computer aseismograms.

Time series derived from observational data or entirely generated by a

Appendix

Instrument CodeW
Orientation CodeS
D
Dip/Azimuth:
Channel Flags:A

Instrument CodeX
Orientation Code
Similar to the observable data that was modified or the observable equivalent for generated
time series (synthetics). See Orientation Codes for the corresponding observed channel.
Further Usage:
In order to document the provenance of the data, SEED header information must be available that
documents the algorithms, processes, or systems that modified or generated the time series. A Channel
Comment Blockette (059), providing a Uniform Resource Locator (URL), must be included. The information available at the URL must identify the processes that were applied to modify or generate
the time series. This information must reference the FDSN web site (http://www.fdsn.org/synthetic).
In addition to the requirement to include a B059, it is required to put a short descrition of the process/instrument in the 30 character channel comment (field 7 of B052).
Non-specific Instruments: The instrument code in SEED format covers most commonly used instrumentsthat generate time series. For instruments not specifically covered by an existing instrument code the Y
instrument code can be used.
Instrument CodeY
Orientation CodeInstrument Specific. Should be documented in the URL referenced below.
Further Usage:
In order to document the instrument type and provenance of the data, SEED header information must be
available that documents the instrument that was used to generate the time series. A Channel Comment
Blockette (059) must be provided in the SEED metadata. The Channel Comment Blockette should provide
a short description of the instrument, the type of measurement it makes and provide a Uniform Resource
Locator (URL) referencing the FDSN web site (http://www.fdsn.org/) that fully describes the instrumentation.
In addition to the requirement to include a B059, it is required to put a short description of the process/instrument in the 30 character channel comment (field 7 of B052).

Standard for the Exchange of Earthquake Data - Reference Manual • 139

Appendix A

Synthesized Beams:

This is used when forming beams from individual elements of an array. Refer toblockettes 35, 400, & 405.
Instrument CodeZ
Orientation CodeI
CFO
Dip/Azimuth:
Signal Units:
Channel Flags:

Incoherent Beam
Coherent Beam
FK Beam
Origin Beam
Ground motion vector (reverse dip/azimuth if signal polarity incorrect)
M, M/S, M/S**2, (for G & M) M/S**2 (usually)G

Channel CodeWe suggest that two sequences be reserved for special channels: the “LOG” channel for the console log, and the “SOH”
channel for the main state of health channel. Subsidiary logs and state of health channels should begin with the “A” code;
the source and orientation fields can then be used in any way.
Here are some typical channel arrangements used by a GSN system:
ChannelDescription

EHZ/EHN/EHE
BHZ/BHN/BHE
LHZ/LHN/LHE
VHZ/VHN/VHE
BCI
ECI
LOG
ACE
LCQ
OCF

Short Period 100 sps
Broad Band 20 sps
Long Period 1 sps
Very Long Period 0.1 sps
Broad Band Calibration Signal
Short Period Cal
Console Log
Administrative Clock Error
1hz Clock Quality
Opaque Configuration FileNOTE: Log Records: Log records has a channel identifier code of “LOG” and a sample rate of zero. The number ofsamples field is the number of characters in the record (including the carriage return and line feed that terminates eachline). Log messages are packed into records until a message falls into a new minute. Log records have no blockettes, so
the strings start at offset 48. For examples of Log Records, ACE, and OCF channels, refer to the end of Appendix E.

140 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix B

Appendix

B

Appendix B: Compression Algorithms
Steim1 Compression Scheme
Contributed by C.R. Hutt
Within a time series of signed 32-bit integers (2’s complement format), each data sample or integer consists of four
bytes (1 byte = 8 bits). Such a time series representing seismometer output data under normal seismic background conditions is usually highly correlated — that is, each data sample is highly predictable, given the previous few samples.
Also, the normal seismic background tends to be of a fairly low frequency compared to the sample rate, so that differences between consecutive samples are generally quite small compared to a full-scale 32- bit number. In fact, suchdifferences seldom require more than four or five bits to represent them to the same accuracy found in the original
32-bit number. These differences, then, can easily be represented as 1-byte quantities without any information loss. If
we do this, we can significantly compress the data and reduce the space required to store it.
Significant seismic activity, however, can create consecutive differences larger than an 8-bit quantity. In such infrequent cases (less than one per cent of the time), a 2-byte or a 4-byte quantity can be used to represent the sample
difference. But we would need some kind of code to tell us when a sample difference is fully represented by one byte,
two bytes, or four bytes. Given this code and the first data sample (not the difference), we could then reconstruct theoriginal 32-bit series of data samples with a series of differences that are each only eight bits wide more than 99 percent of the time. If such a scheme is used to store data on magnetic tape or some other storage medium, we can achieve
a compression ratio of greater than 3.5 to 1, compared to storing all of the original data samples in 32-bit format.
Let the original time series be the samples x-1, x0, x1, …, where each xi is a 32-bit (or smaller) signed integer. Let d0, d1,…, be the first difference time series ,where:
d0 = x0 – x-1’
d1 = x1 – x0’:
Standard for the Exchange of Earthquake Data - Reference Manual • 141

Appendix B
di = xi – xi-1’
di+1 = xi+1 – xi’:
dn = xn – xn-1
The di are all 32 bits wide. Now we look at each di to see if we can represent them with eight bits or 16 bits instead of 32
bits. If we can represent four consecutive di with eight bits, then we can form a single 32-bit word wk that represents four
8-bit quantities:(di)1, (di+1)1, (di+2)1, (di+3)1
where the subscript “1” means “the 1-byte version of what is in the parentheses.” We can keep track of the fact that wk
represents four 8-bit quantities with a 2-bit code, ck = 012.
Suppose now that one or both of the first two consecutive di will not fit within eight bits, but both will fit within 16 bits.
That is, if di is positive, greater than 127 and less than or equal to 32,767, or if di is negative, greater than or equal to-32,768 and less than -128, then we will construct a wk that consists of two 16-bit quantities:(di)2’ (di+1)2’
where the subscript “2” means “the 2-byte version of what is in the parentheses.” Again, we keep track of the fact that wk
represents two 16-bit quantities with a 2-bit code, ck = 102.
Now suppose that di is greater than 32,767 or less than -32,768. This means that we need more than 16 bits to represent
it with no loss of information, so we let wk equal (di)4, where the subscript “4” means “the 4-byte version of what is in theparentheses.” We keep track of the fact that wk represents one 32-bit quantity with the 2-bit code, ck = 112.
In cases where ck does not correspond to any of the 1-byte, 2-byte, or 4-byte sample differences, we let ck = 002. This is a
special two-bit code standing for anything other than data differences, such as header information.
Next, we need a convenient record format for storing ck, wk, and header information on the volume. Since the wk contains
only the difference di, the header must include a forward integration constant: the 32-bit quantity x0, so that all subsequentvalues in the time series (x1,x2, …) can be calculated, as follows:
x0 = x-1 + d0,
x1 = x0 + d1,:
xi = xi-1 + di,:
xn = xn-1 + dn
We also include the reverse integration constant x n , so that the time series could be calculated backwards from the lastdifference in the record, in case of bit errors in the middle of the record:
The reverse integrating constant also provides for a quick data integrity check when compared with the last computed
sample. A discrepancy indicates that the contents of the data are garbled.
xn-1 = xn - dn,:
xi = xi+1 - di+1,

142 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix B
xi-1 = xi - di,:x0 = x1 - d1
The reverse integrating constant also provides for a quick data integrity check when compared with the last computed
sample. A discrepancy indicates that the contents of the data are garbled.

d0 = x0 - x-1 = x0.
The following figure shows the volume format used for the compressed data. Place the data in a data record starting at
byte 64. The records’ size should be 4096 bytes, but if memory constraints disallow such a buffer size, use a smaller
size. The first 64 bytes will always contain the fixed data header (bytes 0 through 47 will contain the actual data
header, and the following 16 bytes will be set to zeros). 63 data frames will follow.

Figure 13: Compressed Data Format
Each ck is a 2-bit nibble code that corresponds to a 4-byte quantity in the frame:
ck = 002 = special: wk contains non-data information, such as headers or w0
ck = 012 = four 1-byte differences contained in wk (four 8-bit samples)
ck = 102 = two 2-byte differences contained in wk (two 16-bit samples)
ck = 112 = one 4-byte difference contained in wk (one 32-bit sample)
Standard for the Exchange of Earthquake Data - Reference Manual • 143

Appendix

Note that any given record will contain n + 1 differences (d0 - dn), and that xn for this record will be equal to x-1 for the
next record. Note also that, when the recording system is cold-started, x-1 is not known and so is set to zero. This meansthat on a volume’s first record, when the system is cold-started or re-initialized, we will have:BAppendix B
c0 corresponds to w0 (which always contains the code bits), so c0 always equals 002. In frame 0, c0 = c1 = c2 = 002; c3through c15 correspond to w3 through w15. In frame 0, w1 = x0 (the forward integration constant) and w2 = xn (the reverse
integration constant).
The figure above has a 64-byte header — followed by 63 data frames, each of which is 64 bytes wide — so that the record
is 4096 bytes long. The first four bytes (w0) of each frame contain 16 2-bit codes c0 through c15 for that frame. The first
frame (frame 0) contains the integration constants in the next 8 bytes (w1 and w2). w1 = x0, the forward integration constant,
and w2 = xn, the reverse integration constant. In Frame 0, w3 through w15 contain sample differences di as specified by the
2-bit codes c3 through c15. Subsequent frames (1 through 62) each contain codes c0 through c15 in w0, and w1 through w15
each contain four 1-byte, two 2-byte, or one 4-byte difference as specified by codes c1 through c15. Since each frame cancontain a maximum of 60 differences (frame 0 has eight less due to the constants stored there), each data record cancontain a maximum of (63 X 60) - 8 = 3,772 differences, corresponding to 3,772 original data samples (including x0 fromthe header). The very first difference (d0) of the data actually represents the difference between the last sample of theprevious record, and x0, the first sample of the current record.
On the other extreme, if every wk corresponds to only one 32-bit difference (no compression at all), then all frames cancontain 15 differences (except for frame 0 which has 13). The minimum number of differences is (63 X 15 ) - 2 = 943 differences. This corresponds to 943 original data samples (including x0). The data format, however, allows the record to be
any length shorter than this. So, when the number of samples (in the fixed data header) have been read, everything in therecord after that number is ignored.
If differencing and compression are not used and we record, instead, the original data samples in 32-bit format, using four
bytes for every sample and no code, then all frames would contain16 data samples for a total of (63 X 16) = 1,008 data
samples per record. If all of the data samples were compressible to 8-bit differences, the same information could havebeen recorded in 1,008/3,772 of a record, or 0.267 records. This is a compression ratio of about 3.75 to 1; that is, about 3.75
compressed data samples can be put into the same space as one uncompressed data sample. If we assume that the data arecompressible to eight bits 99% of the time and must be represented as 32 bits 1% of the time (this is worst case, since partof this 1% would be 16- bit compressed data), the compression works out to be approximately 3.72 to 1 — still well over
3.5 times more data per volume than without compression.
This example assumes a header length of 64 bytes followed by 63 data frames. A situation such as an event detection ora calibration could force the header to be larger then 64 bytes. In this case, create a 128-byte header, followed by 62 data
frames.
Several differences exist between compressed and uncompressed tape formats, but these do not seem to be great disadvantages:•

Data must be “decompressed” or converted to original 32-bit data samples before analysis.

•

Only one single channel of data should be contained in a record. Several seismic data channels should not be multiplexed into a single record, since the compression ratios for channels will usually differ.

•

Although the records are often fixed in length at 4096 bytes, they are not required to be that size, and they are also
not fixed in the number of samples per record. With Steim1 compression, each record may contain from 943 to 3,772
samples. The maximum number of samples a 4096 seed record could contain with Steim 2 is 6601. This meansthat the header time differences between consecutive records of the same data channel will not be fixed, but can becalculated easily by using the sample rate and the number of samples represented in each record. Consequently, therecording system computer must place the number of samples for each record in the header of that record.
Note: This algorithm is copyrighted by Dr. Joseph Steim.

144 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix B

Steim2 Compression Scheme
Contributed by Caryl Peterson

ck =

002 =

same as Steim1, special: wk contains non-data information

ck =

012 =

same as Steim1, four 1-byte (8 bit) differences contained in wk

ck =

102 =

look in dnib, the high order two bits of wk

ck =dnib =

012 = one 30-bit difference in wk

dnib =

102 = two 15-bit differences in wk

dnib =

112 = three 10 bit differences in wk

112 =look in dnib, the high order two bits of wk

dnib =

002 = five 6-bit differences in wk

dnib =

012 = six 5-bit differences in wk

dnib =

102 = seven 4-bit differences in wk

If the difference between two samples is between -8 and +7, that difference can be expressed in 4 bits. If seven consecutive differences are in this range, the compression algorithm puts seven of these 4-bit differences in a single 32 bit
word using 28 of the available 32 bits. The ck in w0 would be 112 indicating that either seven 4-bit differences, six 5-bit
differences, or five 6-bit differences are in wk. The high order two bits of wk would contain 102 to indicate that seven
4-bit differences are in the last 28 bits of wk. The two bits following dnib would not be used.
Negative differences between -16 and -8 or positive differences between +7 and +15 would take 5 bits to represent. Sixconsecutive differences in this range could be placed in a 32-bit word. Again, ck in w0 would contain 112, but the highorder two bits in wk would contain 012 meaning that wk contains six 5-bit differences.
Six bits could represent differences that fall in the range between -32 and -16 or +15 and +31. The ck bits in w0 would
still be 112, but dnib, the high order two bits of wk, would be 002, and the remaining bits would contain the five differences.
Differences lying between -128 and -32 or +31 and +127 would be represented by 8 bits. In this case, all 32-bits of theword are used by four of these 8-bit differences. No further decoding of ck is necessary in the case of 8-bit differences.

Standard for the Exchange of Earthquake Data - Reference Manual • 145

Appendix

The second Steim compression scheme, called “Steim2”, allows for a greater variety in the number of bits used torepresent the differences. In all the cases except one (8 bit differences), the high order two bits in the 32-bit word (wk)of compressed data samples is needed for further decoding of the compression scheme. These high order two bits will
be referred to as dnib, for “decode nibble”. In the following description, ck is the same as described in Figure 13, anddnib refers to the high order two bits of wk.

BAppendix B

Figure 14: Steim2 compression data format
Ten bits would represent differences that are negative and greater than or equal to -512 but less than -128 or positive andgreater than +127 but less than or equal to +511. In this case, ck would be 102 to indicate either one 30-bit difference,
two 15-bit differences, or three 10-bit differences; dnib would be 112 indicating that three 10-bit differences are in theremaining 30 bits.
If the differences are between -16384 and -512 or between +511 and 16383, 15 bits represent those differences. Two ofthese differences would be placed in wk. ck would be 102 and dnib would be 102.
The largest differences that could be represented by Steim2 are those differences that are between -229 and -214 andbetween +214-1 and +229-1. These differences are represented by 30 bits. If a difference is in this range, one 30 bit difference is placed in wk; ck is 102 and dnib is 012.
Figure 14 shows an example of a frame of compressed data where each of the first eight wk are comprised of unique sized
differences.
The best compression ratio is achieved with Steim2 if all the differences can be expressed in 4 bits. In this case, the compression ratio is 6.74 to 1. In a comparative study of data compression schemes, the best compression ratio for Steim2 was
6.07 to 1. This compression ratio was achieved on 20 Hz low noise seismic data. The same data was compressed using the
146 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix B
Steim1 compression scheme. In that case, the compression ratio was 3.67 to 1. In a seismically noisy environment or
during large events, the compression ratio for both schemes is reduced.

USNSN Data Compression
Contributed by Ray Buland

In USNSN compression, preprocessing is a simple first differencing that requires at least one integration constant to be
recoverable. Encoding is patterned on a scheme developed at the Geological Survey of Canada by Ken Beverly. Eachkey field corresponds to a fixed number of fixed length data fields. Taken together, the data fields belonging to one key
field always begin and end on an (8-bit) byte boundary in the computer storage, but will, in general occupy different
numbers of bytes for different key values. The organization and definitions of the key values has been modified fromthe Canadian scheme to adapt it for fixed length records and to achieve less key overhead for small data values. A
fixed length header section is provided for at the beginning of each record as part of the header. Only the first constantis actually required. In addition, back pointers are imbedded into the encoded data and a reverse integration constantadded at the end of each time series. This redundant information has been added to permit the recovery of as muchdata as possible should any portion of the compressed data be corrupted.
Before describing the algorithm in detail, it is useful to define some specialized terms to avoid ambiguity.
Data Value: The digitally encoded value of a sensor output. Note that the data values acquired by an analog-to-digitalconverter and the data values used in a computer must be numerically identical, but may be encoded differently (e.g.
fixed versus floating point or different sign representations). The format of a data value encoded into a data field may
be different again and will have been preprocessed as well.
Time Series: A time series is a number of data values acquired from one sensor output at contiguous, equally spaced
time intervals.
Byte: A number of contiguous bits in computer storage. Standardization in the computer industry has specialized theuse of the term byte to mean eight contiguous bits. A byte is generally the smallest individually addressable unit ofcomputer storage.
Record: A fixed length logical record of computer mass storage. Because of the organization of most modern massstorage devices, a moderately large power-of-two number of 8-bit bytes will provide both rapid access and compact
storage.
Header: A fixed length section of user defined information located at the beginning of each record. Note that a portionof the header is reserved for information required by the compression algorithm.
Standard for the Exchange of Earthquake Data - Reference Manual • 147

Appendix

The United States National Seismic Network data compression scheme follows the same philosophy as all other datacompression methods in common use for seismological data today. Compression depends on the fact that seismological
data acquisition systems are designed to record very large values of ground motion that are very rarely attained. Thus,
the compression results from eliminating as much of the sign extension portion of each raw data value as possible insuch a way that the original value is exactly recoverable. The algorithm is divided into two portions: preprocessing tominimize the fluctuations of the (preprocessed) data about zero as much as possible, and encoding of the data values
into variable length data fields and adding information in accompanying key fields to permit decoding. In addition,
the algorithm makes provisions for effective use of fixed length (computer storage) records, imbedded header information (channel identification, time, status, etc.) and redundant information to promote fault recovery. The NEIC has
programmed this algorithm in FORTRAN for little endian machines and in C for big endian machines. Conversion toother systems is not difficult.

BAppendix B
Trailer: A fixed length section of compression algorithm defined information located at the end of the last record of a timeseries.
Nibble: A variable number of contiguous bits of computer storage (a generalized byte). Thus, while all bytes henceforthwill be 8-bit bytes, nibbles may be 4-bits, 6-bits, 8-bits, etc. The largest nibble used will be 32-bits (the length of astandard integer (long integer, longword, etc.).
Data Field: A nibble containing one preprocessed, encoded data value.
Data Section: A number of contiguous data fields.
Key Value: An unsigned integer constant specifying the encoding of a data section.
Key Field: A nibble containing one key value.
Key Section: A number of contiguous key fields.
Frame: A key section and all of its corresponding data sections.
Block: A number of frames preceded by block header information and/or followed by block trailer information.
In USNSN compression, each time series is preprocessed and encoded into a number of 2048- byte (211) records. Notethat this implies that all data is demultiplexed. Demultiplexing is required as it is the continuity of data from one sourcethat make the first differencing preprocessing effective. All data values are presumed to be representable as fixed point
numbers (integers) for encoding purposes. The length of the header is user definable but must be constant once set. Six
bytes of the header are required by the algorithm for a 4-byte, 2’s complement forward integration constant and a 2-byte,
unsigned number of first differences encoded in the record (subsequently called the record sample count). In the USNSN
telemetry scheme, there is the 14-byte general header, the 6-byte data header, the 6-byte compression header (for 26 bytes),and 10-bytes reserved for the X25 protocol. Therefore, there are 2012 bytes left for the compressed data (including keys,
block delimiters, and the trailer). The trailer is 5-bytes long and includes a 1-byte, unsigned number of first differences
encoded in the last frame (hereafter called the last frame sample count) and a 4-byte, 2’s complement reverse integration
constant. Note that the trailer appears only at the end of the last record of a time series and is used only for backwards
decompression in the case that the last record has been corrupted.
With the exception of user defined information in the header, all information stored by the compression algorithm is in theform of fixed point numbers. All data values (integration constants and first differences) are represented in 2’s complement notation and all control information (sample counts, key values, and back pointers) are unsigned.
If the time series is denoted by A(0), A(1), A(2),...A(n) then the preprocessed series can be denoted by A(0) plus B(1)=A(i)A(i-1), i=1, 2,...,n, where A(0) is the first integration constant and A(n) is the reverse integration constant. Only the B(i)are encoded into the compression frames. If B(i),i=1, 2,...,m first differences will fit into the first record, then the record
sample count (in the header) will be m. However, there will actually be m+1 data values in the record as the first integration constant is an independent datum. The forward integration constant in the second record will be A(m) and the firstdifferences in the second record will begin with B(m+1). Note that integration constants after the first are redundant.
They are provided to permit maximal data recovery should any portion of the compressed data be corrupted. They arealso useful as consistency checks. Because the forward integration constant is redundant, the record sample count in
the header of the second record is the actual number of data in the record. Succeeding records are encoded in the same
way with the trailer (including the reverse integration constant) added to the end of the last record. USNSN time codes
attached to compression blocks reflect the fact that the first record of a compression set will return one more data value
148 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix B
than subsequent packets. If it is necessary to begin decompression with a packet other than the first one, the time code
must be corrected by minus one digitizing interval.

The key values and their meaning is as follows:
key value
0
1
2
3
4
5
6
7
8
9
10
11

number ofdata fields
4
8
12
4
8
4
8
4
8
4
4
4

nibble length(in bits)
4
4
4
6
6
8
8
10
10
12
14
16

data section length(in bytes)
2
4
6
3
6
4
8
5
10
6
7
8

As in all compression algorithms, encoding the last record poses special problems. For all records except the last, theforward integration constant for the following record provides a reverse integration constant. Also, the sum of the data
field length (specified by the keys) and the record sample count (specified in the record header) are redundant. This
redundancy is needed for backward decompression. It is possible because of the zero fill at the end of the record andthe fact that the back pointers must be non-zero (thus, the last non-zero byte of each record, except the last, is the backpointer for the last block). Because, in general, the amount of data in the time series will not fill the last record, thetime series must be padded with zero first differences in order to fill the last frame of the last block. Note that this may
require the entire second data section of the last frame to be padding. In forward decompression, the record sample
count in the header will specify the true last point in the original time series. For backward decompression, a trailer isadded to provide the desired redundancy. The trailer consists of a 1-byte last frame sample count (the actual numberof first differences, not padding, encoded in the last frame) and the reverse integration constant. The count is placed
immediately after the back pointer for the last block and the reverse integration constant is placed in the last four bytesof the record. The byte between the count and the reverse integration constant must be zero.
NOTE: When data compression packets are sent over the network, the reverse integration constant is stored as the last
four bytes of the packet. The receiving program must check for an ’end-of-file’ bit in the packet and if it is found, movethe last four bytes of the packet to the end of the compression buffer and zero fill any bytes between where the reverse
integration constant was stored and where it is moved. Hence, if the compression block length is 2012 and a packet
received via the satellite system is marked with end-of-file and indicates the compression block portion of the packet(i.e. the total packet length less non-compression block overhead) is 2006 bytes long, bytes 2003-2006 are copied to
2009-2012 and bytes 2003-2008 are zero filled. This is done so that packets going through the satellite system do notneed to send the needless zero filled bytes. This is, of course, more important when the satellite packet is considerably
shorter than a full packet.
Standard for the Exchange of Earthquake Data - Reference Manual • 149

Appendix

The compression algorithm encodes sequences of 4, 8 of 12 successive first difference values into a data section
comprised of consecutive data fields of the same nibble size and assigns the data section a 4-bit key value. Nibble sizesof 4-bits, 6-bits, 8-bits, 10-bits, 12-bits, 14-bits, 16- bits, 20-bits, 24-bits, 28-bits, and 32-bits are supported. Note thatdata sections are an integral, but variable number of bytes long. The key section is made up of two keys and is thus,
1-byte long. A frame consists of one key section followed by the two corresponding data sections. A block consistsof seven frames followed by a 1-byte block trailer containing a back pointer. The back pointer is an unsigned integer
specifying the number of bytes in the block. The back pointer can be used to decompress backward (from the reverse
integration constant) and it provides a consistency check when decompressing in the forward direction. All records
except the last consist of a header section and as many blocks as will fit. The last block may contain less than sevenframes, but should contain as many frames as will fit in the record. All frames, including the last, must be completely
filled with data values. The remainder of the record, following the last block trailer, must be zero filled.

BAppendix B
Compressing data using the USNSN algorithm is straightforward. Each record is constructed in memory and then written
out. The data is first differenced as needed and is analyzed in groups of four first differences to determine the nibble sizethat may be used. A four first difference look ahead is maintained at all times to determine whether a longer run can be
encoded (for small nibble sizes) and if the record is full. Each time enough data is available, a frame is encoded. Every
seven frames, the back pointer is computed and added. Determining the forward integration constants after the first is alittle tricky due to the look ahead. Constructing the trailer is obvious. Problems with determining when a record is full are
eliminated by the simplicity of the algorithm and the look ahead.
Forward decompression is also straightforward. Beginning with the first forward integration constant, frames are decoded
and the first differences integrated to recover the input data values. At the end of each block, the back pointer should bechecked for consistency. The number of first differences in the record can be used to determine when the last frame in
the record has been processed. At the end of the record, the number of samples and the forward integration constant at
the beginning of the next record should also be checked for consistency. In the last record, the number of first differencesin the record should be used to determine both when the last frame has been reached and how many first differences in
the last frame are data and not padding. The number of samples in the frame should be checked using the number of firstdifferences in the last frame from the trailer and the reverse integration constant should be checked for consistency.
In fact, the presence of the number of first differences in the last frame count (which must be non-zero) is a flag for the lastrecord (and hence, the end of the time series). Note that decompression may begin from any record in the time series ifnecessary.
Backward decompression is not quite as easy. In this case, decompression begins from the end of a record. If this record
is the last record, the integration constant is available from the trailer. The number of first differences in the last frame
count can be found by skipping over the zero fill. The next byte backwards will be the last block back pointer. The backpointer is used to compute the location of the start of the block. From this point all of the key fields in the block may belocated and decoded (to give the location of the next key field and the number of first differences in the frame). In thisway, the number of first differences in the block can be computed (using the actual number of first differences in the last
frame from the count). Note that the number of frames can be determined from the back pointer position. In fact, if thelast frame does not end on the byte before the back pointer position, then the block is inconsistent. Once the number of firstdifferences is known, the data can be decoded and backwards integrated to recover the original data values. Successive
blocks are decoded in the same way, but are somewhat easier as there will always be 7 frames in each block and the last
frame count is not needed. If they are available, the number of first differences in the record and the forward integration
constant in the header can be checked for consistency. If backwards decompression begins in a record that is not thelast, the procedure is the same except that the forward integration constant in the next record must be used as the reverse
integration constant. Also the last frame count will not be available, but will not be needed as the last frame will be fullof data.
Note that the consistency checks are available to determine where the data may have been corrupted. If such a place isfound, forward decompression cannot continue until the next uncorrupted header. Some of the data between the next
header and the corrupted location can be recovered by backwards decompression. Care must be exercised, however, as
the backwards decompression uses the back pointer, which may also be corrupted.

150 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C

Appendix

C

Appendix C: Specifying and Using
Channel Response Information
Contributed by C.R. Hutt

Introduction
SEED volumes usually use complex-valued functions of frequency in response functions. Usually, these functions
will not be single expressions, but rather the products of several expressions. Most seismic systems can be regarded as
cascades of stages — for example, a seismometer, followed by an amplifier, followed by an analog filter, followed byan analog/ digital converter, followed by a digital filter. A blockette’s stage sequence number shows the order of thestages, as shown in figure 1 below:

Figure 1: Example of a sequence of stages.
Before the age of high speed digital computers and digital signal processing (DSP) chips, all low-pass filtering (for the
purpose of preventing aliasing) was performed in the analog stages before digitizing. The digitizer would operate ata fairly low sample rate equal to the sample rate being recorded. Typically, the corner frequency of the low-pass filter
would be 1/8 to 1/20 of the sample rate (1/4 to 1/10 of the Nyquist frequency). Therefore, the low-pass anti-alias filter
response would typically begin to attenuate at frequencies well within the band of interest.
Modern seismic data acquisition systems make use of over-sampling and decimation (to grossly over-simplify the innerworkings of high resolution ADC’s) to achieve high resolution. This technique relaxes the analog anti-alias filtering
requirement and moves the low-pass filtering job into the digital domain. Decimation (sample rate reduction) must be
preceded by sufficient low-pass filtering to prevent aliasing at the new lower sample rate. Many modern high resoluStandard for the Exchange of Earthquake Data - Reference Manual • 151

Appendix Ction ADC’s include two or more stages of Finite Impulse Response (FIR) filters to accomplish this task. These may befollowed by further low-pass filter and decimate stages within the data acquisition computer to derive lower sample rate
data streams (such as deriving Long Period data from Broadband data).
FIR filters are simply weighted averages of some number of data samples — the “weights” are the coefficients specified in
Blockette (54) (for a “D” type stage). FIR filters are usually designed to approximate a “boxcar” response. That is, they
typically have a very flat in-band response and a sharp, steep cut-off at their corner frequency, which may be set at 70% to
90% of the Nyquist frequency. In-band ripple is usually only a few percent. Also, FIR filters are usually designed to havelinear phase, and the data acquisition systems usually time-tag the data so that the phase shift appears to be nearly zero.
All of this means that the average data user probably doesn’t need to correct for the effect of such FIR filters.
Examples of some common FIR filter amplitude responses for 20 sps data are shown in Figures 2 through 5 following.
Note that in-band ripple can be several percent, but corner frequencies (-3 db points) are usually very close to the Nyquist
frequency (which is 1/2 the sample rate). Also note that stop band gain can vary significantly: from -75 db to -120 db inthese three examples.
It was previously stated that modern data acquisition systems using digital FIR filters usually time tag the data so that thefilter delay (phase lag) appears to be nearly zero. Figure 2.B. contains a plot of the phase shift that results when the data
are time tagged in such a way as to correct precisely for the theoretical filter delay (which is 1.625 seconds in this case).
As is stated later in this Appendix, Blockette [57] should always be used when specifying a digital filter to completely
describe how the time tag is applied. Some data acquisition systems (those installed through August 1992 by the USGS)
correct for the FIR filter delays, resulting in near-zero phase shift, but did not specify this in a Blockette [57]. A data user
may take the absence of Blockette [57] to mean that there exists a phase lag in the data that is really not there in thesesystems. That is, a Fourier transform of the FIR coefficients would indicate a pure delay, when in fact there is really nodelay. The absence of Blockette [57] in USGS-supplied data will be remedied as soon as possible after August 1992.
Anyone specifying digital filters in SEED format should always include the complete specification, including Blockette[57].

152 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C

AppendixC

Figure 2A

Figure 2b
Figure 2: Amplitude response of combined FIR filters used in Martin-Mariette digitizers of IRIS/USGS IRIS-2
systems, 20 sps (BB) data. Gain has been normalized to OdB at O Hz (DC). Note the different scales in thetwo figures above.

Standard for the Exchange of Earthquake Data - Reference Manual • 153

Appendix C

Figure 3A

Figure 3B
Figure 3: Amplitude response of combined FIR filters used in “Quantagrator” model digitizers built by
Quanterra, Inc. for 20 sps (BB) data. Gain has been normalized to Odb at OHz (DC).

154 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C

AppendixC

Figure 4A

Figure 4B
Figure 4: Amplitude response of combined FIR filters used in Q380 and Q680 model digitizers built by
Quanterra, Inc. for 20 sps (BB) data. Gain has been normalized to Odb at O Hz (DC).

Standard for the Exchange of Earthquake Data - Reference Manual • 155

Appendix C

Figure 5A

Figure 5B
Figure 5: Amplitude response of Ormsby FIR filter used in the Reftek 24-bit digitizers of the IRIS/IDA
IRIS-3 systems. 20 sps (BB) data. Gain is 0 dB at 0 Hz (DC). Note the different scales in the two figures
above.

156 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C
In Figure 1, the seismometer response would have stage sequence number 1 and the digital filter would have stage
sequence number 5. If there are K stages and the complex frequency response of the i-th one is Gi (f), the system
response is:K∏ Gi (f)(1)

i=1Appendix

This appendix will show how to represent the stages (Gi’s) using SEED blockettes. In Figure 1, each stage can be
described by one or a combination of blockettes. Analog stages may be partially described by either Blockette [55](Response List) or by Blockette [56] (Generic Response), but must also be described fully by using either the Poles andZeros Blockette [53] or the Coefficient Blockette [54] along with [58] Channel Sensitivity/Gain Blockette:

C

Figure 6: Example Analog Stage Using Poles and Zeros Representation
Note that Ao is chosen so that, at the normalization frequency, f n, |H(i2πf n) | A0 = 1.0. Also note that it is most convenient, and strongly recommended, that fn = fs.

Figure 7: Example Analog Stage Using Coefficients Representation
Note that the coefficients of H(s) are chosen so that at the frequency of sensitivity fs.|H(i2πfs).=1.0. Here fs should beequal to fs and f n for all previous stages in the sequence, if possible.

Figure 8: Example Digital Stage Using Coefficients Representation
The coefficients are chosen so that at the frequency of sensitivity fs’ |H (e2πifs∆t)| =1.0. Here, fs should be equal to fs and f n
for previous analog stages in the sequence, if possible. If the digital stage is a FIR filter, it is also convenient to use fs =0 Hz (DC), because the DC gain of a FIR filter is just the sum of the coefficients. However this should only be done if
the DC gain is within 1% or 2% of the gain at fs in previous stages.

Standard for the Exchange of Earthquake Data - Reference Manual • 157

Appendix C

Conventions
At any frequency, the modulus (absolute value) of the complex response function is the amplitude response of that stage.
The phase of the complex response function is the phase response of that stage, with negative phase (output phaselagging the input) indicating a delay. Analog stages are represented by the Laplace transform of the linear system impulse
response:
H (s) = ∫0∞ h (t) e-st d t(2)h(t) is called the stage impulse response function, and its transform, H (s), is called the stage transfer function. H(s) may
be specified in polynomial form (Blockette [54]) or in factored form (Blockette [53]).
Digital stages are represented by the Z-transform of the sampled time series corresponding to the stage impulse response:∞
H (z) =
hm z-mm = -∞∑(3)

hm is called the stage impulse response function, and its transform, H (Z), is called the stage transfer function. H(z) may
be specified in polynomial form (Blockette [54], usually used for FIR filters) or in factored form (Blockette [53], usuallyused for IIR filters).

Normalization
For most stages, the frequency response is given in the form:
G (f) = Sd R (f)(4)

where R (f) is a function of frequency (usually complex-valued), specified by some combination of Blockettes [53], [54],[55], [56], and [57] (see below for which combinations are preferred for particular systems). R (f) is normalized so that
| R (fs) | = 1.0, where fs is the frequency specified in Blockette [58]. Sd is the stage gain at that frequency. Using frequency
response normalization helps by providing a check (you can compute G (fs) and make sure that it is indeed Sd), and bykeeping track of the response functions of analog systems.
In cases where G(f) corresponds to an analog-type stage, a Poles and Zeros type response Blockette [53] is normally used
to specify this stage. In this case, R(f) is expressed in this form:
R (f) = A0 H p (s)(5)

where s = i 2 π f or s = i f (i = √ -1 ) as specified below equation (6) and Hp (s) represents the transfer function ratio of
polynomials specified by their roots, as in equation (6). For proper normalization, we chose A0 such that | R(fs) | =1.0; thatis A0 = 1/|Hp(ss) |, where ss= i2πfs rad
sec or ss= i fs (depending on whether we have represented the poles and zeros of Hp interms of radians per second or Hz).
In cases where G(f) corresponds to an analog-type stage and the coefficient representation is used, as in equation (7), thenthe coefficients aj and bj of Hc(s) are chosen such that Hc(ss)|=1.0, where ss= i 2 π fs
or ss = i fs Hz.
When G(f) corresponds to a digital-type stage and is represented with poles and zeros, as is usually the case with IIR
filters (those with feedback), we again chose A0 =1/|Hp(zs)| where Hp(z) is defined as the ratio of polynomials in equation(11), and zs = e2 π i fs∆t, where ∆t is the sample interval and fs is specified in the stage description.

158 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C
Finally, when G(f) specifies a digital-type filter and is represented with coefficients, as is usually the case with FIR
filters (those without feedback), the coefficients bn of Hc(z) in equation (9) are chosen such that |Hc(zs)| = 1.0, where zs
is defined as in the previous paragraph.

A possible exception is when the stage is a low pass digital FIR filter. The stage sensitivity for a FIR stage may bestated at fs = 0 Hz (DC) if the in-band ripple is less than say, 1 or 2%. The DC gain of an FIR filter is the sum of thecoefficients and so is easy to calculate.

Analog Stages
The first part of any seismic sensor will be some sort of linear system that operates in continuous time, rather than
discrete time. Usually, any such system has a frequency response that is the ratio of two complex polynomials, eachwith real coefficients. These polynomials can be represented either by their coefficients or by their roots (poles andzeros). The latter is the preferred mode, but either is acceptable.

Pole-Zero Representation for Analog Stages
The polynomials are specified by their roots. The roots of the numerator polynomial are the instrument zeros, and theroots of the denominator polynomial are the instrument poles. Because the polynomials have real coefficients, complex
poles and zeros will occur in complex conjugate pairs. By convention, the real parts of the poles and zeros are negative,
which leads to the form of function given below.
The fullest possible specification will utilize Blockettes [53] and [58]. Blockette [53] will specify N zeros, r1, r2,…, rN,
M poles p1, p2,…,pM, a normalization factor A0, and a reference frequency. The reference frequency is 1 radian/second
if field 3 of Blockette [53] is the character A, and 1 Hz if field 3 of Blockette [53] is the character B. Blockette [58] will
specify a scaling factor Sd. Then at any frequency f (in Hz), the response is:N

G(f) = Sd A0∏ (s - r )
n=1
M

n

= Sd A0 Hp (s)(6)∏ (s - p )m=1m

where s = i 2 π f if the reference frequency is 1 radian/second, and s =i f if the reference frequency is 1 Hz.
Using two multiplicative coefficients, A0 and Sd, in the equation above appears to be redundant, but we suggest that you
partition the response by choosing A0 so that the modulus of A0 times the modulus of the ratio of polynomials equals
1.0 at the normalizing frequency f n (also specified in Blockette [53]); the Sd specified in Blockette [58] is then the stage
gain at that frequency, so | G (f n) | = Sd. This division allows Blockette [53] to remain the same for many systems, withStandard for the Exchange of Earthquake Data - Reference Manual • 159

Appendix

This normalization works for stages 1 through K. If Blockette [58] has a stage number of 0, SEED assumes that thesensitivity Sd given in field 4 of Blockette [58] applies to the system as a whole, at the frequency fs given in field 5of Blockette [58]. Note that fs should, if possible, be equal to the normalization frequency f n given in any of stages 1
through K. In fact, within any stage, fs should be equal to f n. If no other stages are specified, SEED programs should
conclude that this is our total knowledge of the system response. If we specify other stages, the stage-zero sensitivity
will serve as a check on the sensitivity we can arrive at by multiplying together the responses G1, …, GK. In this case,the stage-zero sensitivity is not multiplied together with the gains of the other stages. Rather, the stage-zero sensitivity
should be equal to the product of the gains of the other stages at frequency fs= f n. If we have not used the same frequencies, fs and f n, for all stages 1 through K, then we can only say that the product of the sensitivities for each stage may
be approximately equal to the stage 0 sensitivity. Note that this idea is much more intuitive and easier to work with if fs
and f n are the same for all stages.

CAppendix C
the small differences between them expressed by the single number Sd in Blockette [58]. This simplifies keeping trackof system responses. The “frequency of sensitivity factor” in Blockette [58] (fs) should be the same as the normalizing
frequency f n in Blockette [53].
If Blockette [53] is omitted, SEED assumes that A0 will be 1. This would be appropriate for an amplifier with no significant departure from a fixed gain Sd, or for a stage about which nothing was known but its gain at one frequency. SEED
allows these combinations of blockettes for a stage of this type: [53], [58] or [58] by itself. Blockette [58] by itself would
correspond to an amplifier with a flat response.

Coefficient Representation for Analog Stages
The polynomials are specified by their coefficients. The fullest possible specification will utilize Blockettes [54] and [58].
Blockette [54] will specify N+1 numerator coefficients, a0, a1,…, aN, M +1 denominator coefficients b0, b1, …, bM. Blockette[58] will specify a scaling factor Sd. Then, at any frequency f (in Hz) the response is:N

G(f) = Sd∑(an sn)n=0

M= Sd Hc (s)(7)∑(bm sm)m=0where s = i 2 π f if field 3 of [54] = A, and s = i f if field 3 of [54] = B.
As in the pole-zero case, the coefficient Sd appears to be redundant, but the response should be partitioned as describedabove by choosing polynomial coefficients so that the ratio of polynomials have a magnitude of 1 at f = fs, so that | G (fs)
| = Sd at the frequency fs (in this case specified only in Blockette [58]); the Sd specified in Blockette [58] is then the stage
gain at that frequency.
If Blockette [54] is omitted, SEED will assume the ratio of polynomials equals 1.
SEED allows these combinations of blockettes for a stage of this type: [54], [58] or [58] by itself.

Analog-Digital Converter
This stage is the transition between the analog stage (for which the input units are ground behavior and the output someother analog signal, usually volts), and the purely digital stages. This stage has no frequency response (except for a possible
delay between the sample-and-hold time and the time-tagging), but it does have a gain (in digital counts per analog unitin). Use Blockettes [54], [57], and [58] to specify the nature of this stage. In Blockette [54], fields 5 and 6 of Blockette[54] give the units involved; fields 7 and 10 of Blockette [54] should both be set to zero. In Blockette [57], field 4 gives
the sample rate, with field 5 set to 1 to indicate that this is also the output sample rate. Fields 7 and 8 of Blockette [57]describe any empirically determined delays and applied time shifts respectively. (Use the delay field, field 7 of Blockette[57], only in this case.) In Blockette [58], field 4 gives the digitizer response (in counts/analog unit); and field 8 may be
any frequency.
Note that it is acceptable (but discouraged) to combine the digitizer description with the first FIR stage. In this case, theinput units would be volts and the output units would be counts.

160 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C

Digital Stages
These stages operate on sampled data, and thus operate in discrete time rather than continuous time. All operations
are digital, done to finite precision; however, SEED does not describe the level of precision actually used, and, for most
purposes, all arithmetic is assumed to be done to infinite precision. In general, a digital stage will consist of:
A discrete-time filter, either FIR (finite impulse response, also called convolution filter), or IIR (infinite impulse
response, also called recursive filter).

2.

Resampling of the filter output to a new rate. Usually this rate is lower, in which case this operation is called decimation.

3.

Time-shifting of the decimated series by assigning a time-tag to each value that corresponds not to the time at which
it was computed, but to some other time. The difference between these times is the time-shift, which is usually
non-positive (where the assigned time is earlier than the actual time) to minimize the phase shift introduced by thedigital filter.

Coefficient Representation for Digital Stages
This type of stage is usually used to specify Finite Impulse Response (FIR) filters. In this type (- ∞ ≤ k ≤ ∞) is
convolved with the L+1 weights or coefficients b0, b1,…,bL to produce the output series yk:
yk =L∑ bn xk - n

(8)

n=0

Filters of this type are specified by Blockettes [54], [57], and [58] (or, in a special case, by using only Blockette [58]).
Blockette [54] contains the weights bn as the numerator coefficients. (There are no denominator coefficients in thiscase.) Blockette [57] specifies the input sample rate and the decimation factor. (Use a decimation factor of 1 if theoutput rate equals the input rate). Blockette [58] specifies a scaling factor, Sd. The transfer function for this filter is:
G (f) =

LSd ∑ bn z-n = SdHc(z)
n=0

(9)

where the z-transform variable is z = e2 π i f Δt, with Δt = the input sample interval specified in Blockette [57], and f is thefrequency in Hz.
Scale the coefficients bn so that | Hc (zs) | = 1.0 where zs = e2 π i fs Δt, fs is specified in Blockette [58]. The Sd specified in
Blockette [58] is then the stage gain at fs.
If Blockette [53] is omitted, SEED will assume that the polynomial is 1.0; this would be appropriate for a pure multiplication.

Pole - Zero Representation for Digital Stages
This type of stage is usually used to specify Infinite Impulse Response (IIR) filters (those with feedback). In this typeof digital filter, the input series x k (- ∞ ≤ k ≤ ∞) is convolved with the LB + 1 weights b0, b1, …, bLB; and past values ofthe output series yk are convolved with the LA weights a1, a2, …, aLA, to produce the output value yk:yk =LB∑ bn xk – nn=0LAan yk – n
n=1

∑

(10)

The transfer function of this filter is:H(z) =

B(z)_________A(z)=b0 +b1z-1+…+bLB z-LB_________________________________(11)

1+a1z-1+…+aLA z-LA

Standard for the Exchange of Earthquake Data - Reference Manual • 161

Appendix

1.

CAppendix C
where the z-transform variable is z = e2 π i f Δt, with ∆t = the input sample interval specified in Blockette [57].
Specify filters of this type with Blockettes [53], [57], and [58]. (Blockette [54] could be used to provide the coefficients,
but because of the loss of precision possible in this case, we recommend not using it.) Blockette [53] will specify LB zeros,
r1, r2, …, rLB; LA poles p1, p2,…, pLA , and a normalization factor A0. The transfer function for the stage is:
(12)

LB

∑ (z – rn)
n=1_____________________

G (z) = Sd A0LA= Sd A0 Hp (z)∑ (z – pm)
m=1

where z is as defined above. Choose A0 so that A0 • | Hp(zn) | = 1.0, where zn =. e2 π i fn Δt. Here f n is the f n from Blockette [53],and should be equal to the fs in Blockette [58]. The Sd, specified in Blockette [58], is then the stage gain at that frequency,with . G (f n). = . G (fs).= Sd.
The zeros rn are the solutions of the equation:
b0 +b1 z-1 +...+bLB z-LB = 0(13)while the poles pm are the solutions of:
1 + a1z -1 …+ aLA z-LA = 0(14)

If Blockette [53] is omitted, A0 will be considered to equal 1.0 (this would be appropriate for a pure multiplication).

Decimation
Blockette [57] specifies this operation. If the input series is y m, the output series is w n, with:
wn = yLn + l , n = 0, 1, 2, ...

(15)

where L is the decimation factor and l is the offset (both are integers). The output sample interval is L times the input
sample interval.

Time-shifting
As the data stream w n emerges from the decimator, at time tT each term is tagged (at least implicitly) with a nominal timetN. Blockette [57] gives the time shift δ = tN - tT implied by this, in seconds. The effect of this time shift is to introduce aphase shift of ei 2 p f δ.

ExamplesIn the following three examples, we will assume we have a seismometer (Stage 1) followed by a digitizer (stage 2) followedby an FIR filter (Stage 3). We will then show an example Stage 0 specification summarizing these 3 stages.

Example of Specifying an Analog Stage 1.
Suppose we have a seismometer with a natural frequency fo of 1 Hz ± 1%, a damping factor λ = 0.7 ± 3%, and a sensitivityof 150 volts per meter per second per second at 1 Hz. The acceleration transfer function would be (ignoring any constantgains):
162 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C
H (s) =s(16)________________________

s + 2 λ ω0 s + ω0
2

2

There is one zero of H (s) at s = 0.The two poles of H (s) are at:s = λ ω0 ± i ω0 √1-λ2(17)

In our example, ω0 = 2π • (1) rad/sec, λ = 0.7, so we have the poles:(18)

r1 = 0 +i 0

(19)

and the zero:

Note that both the real and imaginary parts of p1 and p2 may be in error by 4%, because f 0 was ±1% and λ was ±3%.
However, it is known that both parts of r1 are exactly 0. These errors are specified in Blockette [53], along with the realand imaginary parts of the poles and zeros. For this example, Blockette [53] would be filled out as follows:
Note

Field nameType

Length

Mask or Flags

1
2
3
4
5

Blockette type — 053
Length of blockette
Transfer function typeStage sequence number
Stage signal input units

D

3

6

Stage signal output units

7

AO normalization factor (1.0 if none)

8
9
10
11
12
13

Normalization frequency fn(Hz)Number of complex zeros
Real zero
Imaginary zero
Real zero error
Imaginary zero error

F
D
F
F
F
F

12
3
12
12
12
12

+0.10000E+01
001+0.00000E+00+0.00000E+00+0.00000E+00+0.00000E+00

14
15
16
17

Number of complex poles
Real pole #1
Imaginary pole #1
Real pole error #1

D
F
F
F

3
12
12
12

18

Imaginary pole error #1

F

12

15
16
17

Real pole #2
Imaginary pole #2
Real pole error #2

F
F
F

12
12
12

002
-0.43982E+01+0.44871E+01+0.17593E+00 ( = 4%
of 0.43982E+01)+0.17948E+00 ( = 4%
of 0.44871E+01)

18

Imaginary pole error #2

F

12

053
(length in bytes)
A
1
A
D
2
01
D
3
[M/S ** 2]**NOTE: What goes here is not “M/S **2”, but rather a 3
digit unit look-up code such as “004” that refers to thecorresponding (field #3) code in Blockette [34], the Units
Abbreviations Blockette where “M/S**2” is defined.
D
3[V]**NOTE: see note aboveF
12+0.87964E+01
NOTE: See EXAMPLE OF CALCULATINGAN ANALOG STAGE RESPONSE for information on how to calculate AO.

}}}-0.43982E+01-0.44871E+01+0.17593E+00 ( = 4%
of 0.43982E+01)+0.17948E+00 ( = 4%
of 0.44871E+01)}

From (19)Becauseboth partsof r1 areexactly zeroP1 from (18)

P2 from (18)Standard for the Exchange of Earthquake Data - Reference Manual • 163

Appendix

p1 = - 4.3982 + i 4.4871
p2 = - 4.3982 - i 4.4871

CAppendix C
Note that the errors listed are positive, but represent a plus/minus (±) error expressed in the same units (either rad/sec
or Hz) as the units of the real and imaginary parts of the pole listed in fields 15 and 16. Blockette [58] would be filled asfollows:
Note

Field nameType

Length

Mask or Flags

1
2
3
4
5

Blockette type — 058
Length of blockette
Stage sequence number
Sensitivity/gain (Sd)Frequency (Hz) (fs)

D
D
D
F
F

3
4
2
12
12

6

Number of history values

D

2

058
(length in bytes)
01+0.15000E+03
0.10000E+01
NOTE: fs = fn of Blockette [53].
00This blockette stops here because there are no history values.

Example of Specifying a Digital Stage 2
ANALOG DIGITAL CONVERTER:
Suppose the analog-to-digital converter (ADC) we are using is a 24-bit ADC for which full scale is ±20v = ±223 counts.
We use Blockettes [54], [57], and [58] to describe this stage. We assume the ADC is producing 40 samples per second.
Blockette [54] would be filled out as follows:
Note

Field name

1
2
3
4
5
6
7

Blockette type — 054
D3
Length of blockette
D
4
Response typeA
1
Stage sequence numberD
2
Signal input units
D
3
Signal output units
D
3
Number of numerators
D
4
REPEAT fields 8 — 9 for the Number of numerators:
Not Present
Not Present
Number of denominators
D4
Not Present
Not Present

8
9
10
11
12

Type

Length

Mask or Flags
054(length in bytes)D
02[V] (by reference)[counts] (by reference)
0000

0000

Blockette [57] (We need this one to specify the sample rate.)
Note

FieldnameType

Length

Mask or Flags

1
2
3
4
5
6
7
8

Blockette type
Length of blockette
Stage sequence number
Input sample rate(Hz)Decimation factor
Decimation offset
Estimated delay (seconds)
Correction applied (seconds)

D
D
D
F
D
D
F
F

3
4
2
10
5
5
11
11

057
(Length in bytes.]
02
0.4000E+02
00001
00000
+0.0000E+00+0.0000E+00

Blockette [58]:164 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C
Field nameType

Length

Mask or Flags

1
2
3
4

Blockette type — 058
Length of blockette
Stage sequence number
Sensitivity/gain (Sd)5Frequency (Hz) (fs)6

Number of history values

D
3
058
D
4
(length in bytes)
D
2
02
F
12
+4.19430E+05**NOTE: This number equals 223 counts
divided by 20 volts, in this case.
F
12+0.10000E+01**NOTE: We have specified the sensitivity at fs = 1 Hz, the same frequency at which
we specified the seismometer sensitivity andthe same frequency at which we calculated
the normalization constant AO in stage 1.
D
2
00

Appendix

Note

C

We end the blockette here if there are no history values.

Example of Specifying a Digital Stage 3
FIR FILTER:
Suppose the ADC in stage 2 is followed by a simple running 2-point averager, and we throw away every other sample(decimate by 2) at the output of this stage 3. A simple 2- point average is an example of a FIR filter, with both coefficients equal to 0.5. Suppose further that we want the gain of this FIR filter to be 2 at 0 Hz. One way to accomplish thisin a real implementation is to let both of the coefficients be equal to 1.0 instead of 0.5. (This results in a gain of 2.00 at
0 Hz, or a gain of 1.9938 at 1 Hz. See “EXAMPLE OF CALCULATING A DIGITAL STAGE RESPONSE” below foran example of calculating this gain.)Note: In July 2007, the FDSN adopted a convention that requires the coefficients to be listed in forward order as usedin equation 8. As a reference, minimum-phase filters (which are asymmetric) should be written with the largest values
near the beginning of the coefficient list.
In the form of equation (8), this FIR filter may be written as
y0 = b0 x0 + b1 x-1 = b0 x0, (assume x-1 = 0)y1 = b0 x1 + b1 x0,
:
:
:

(20)

where b0 = 1.0 and b2 = 1.0. The decimation process would keep y0, throw away y1, keep y2, and so on. The delay of thisfilter would appear to be about one-half of the original sample interval of 0.025 seconds, or 0.0125 seconds (the midway point of a plot of the symmetrical coefficients).
We would specify this stage 3 FIR filter by using Blockettes [54], [57], and [58]. Since Blockette [58] needs to specify
the gain separately, assuming that the coefficients listed in Blockette [54] have been normalized to produce a gain of
1.00 at fs = 1 Hz, we list b0 = b1 = 0.50155=1/1.9938.
Blockette [54]NoteField nameType

Length

Mask or Flags

1
2
3
4
5
6
7
8
9

Blockette type — 054
Length of blockette
Response typeStage sequence number
Signal input units
Signal output units
Number of numerators
Numerator coefficient #1
Numerator error #1

8
910

Numerator coefficient #2
Numerator error #2
Number of denominators

D
3
054
D
4
[Length in bytes.]
A
1
D
D
2
03
D
3
[counts] (by reference)D3[counts] (by reference)
D
4
0002
F
12
+0.50155E+00(b0)F
12+0.00000**(error in b0 -- assume zero for accurately stored digital values.)
F
12+0.50155E+00 (b1)F
12+0.00000 (error in b1)
D
4
0000*
*NOTE: Even though we list zero denominator coefficients for FIR filters, we assume that there is a
non-zero denominator value of 1.0, to avoid divisionby zero, when evaluating the filter transfer function.

Standard for the Exchange of Earthquake Data - Reference Manual • 165

Appendix C
Blockette [57]Note

Field nameType

Length123
45

Blockette type — 057
Length of blockette
Stage sequence number
Input sample rate (Hz)
Decimation factor

D
D
D
F
D

3
4
2
10
5

6

Decimation offset

7
8

Estimated delay (seconds)
Correction applied (seconds)

Length

Mask or Flags

057[Length in bytes.]
03
0.4000E+02
00002 (we are throwing
away every other sample)
D
500000 ( we are keeping
the first sample)
F11+0.1250E-01
F11+0.1250E-01**NOTE: We are assuming here that the data acquisition
system is time tagging the data at the output of this FIR
filter in such a way as to correct for the estimated delay.

Blockette [58]NoteField nameType

Mask or Flags

1
2
3
4
5

Blockette type — 058
Length of blockette
Stage sequence number
Sensitivity/gain (Sd)Frequency (Hz) (fs)

D
3
058
D
4
[Length in bytes.]
D
2
03
F
12
+0.19938E+014F12+0.10000E+01**NOTE: We are again quoting the gain at the same
frequency as in previous stages. We could also havequoted the gain as 2.00 at 0 Hz, because it is within 1%of the gain at 1 Hz. (The gain is easy to calculate at 0
Hz because it is just the sum of the coefficients bi.)

6

Number of history values

D

2

00

Example Stage O Specification
Blockette [58] must be used to summarize the overall (stages 1 through 3 in this case) gain, or system sensitivity, at agiven frequency. It is best to specify this sensitivity at the same frequencies fs and f n used in the previous stages. Then thestage 0 sensitivity should be equal to the product of the stage 1 through K sensitivities, if there are K stages in total.
For our 3-stage example, Blockette [58] for stage 0 should be filled in as follows:
Note

Field nameType

Length1
2
3
4

Blockette type — 058
Length of blockette
Stage sequence number
Sensitivity/gain (Sd)

D
3
058
D
4
[Length in bytes.]
D
2
00
F
12
+1.25439E+084*Note: This sensitivity is assumed to be expressedin counts per m/s * * 2; that is, in terms of output
units for stage K per input units for stage 1
at fs = 1 Hz. In this case, it is equal to56Frequency (Hz) (fs)Number of history values

F
D

12
2

Mask or Flags+0.10000E+0100

166 • Standard for the Exchange of Earthquake Data - Reference Manual(21)Appendix C

Example of Calculating Analog Stage 1 Gain and Phase
For our 1 Hz seismometer in the stage 1 example given, we have, using the form in equation (6):Hp(s) =

s+0(22)______________________________________________________________(s + 4.3982 + i 4.4871) (s + 4.3982 – i 4.4871)
A0 = 8.79640 @ fn = 1 Hz
Sd = 0.15000E+03 @ fs = 1 Hz

(23)
(24)

| Hp (i 2 π · fn) | =|0 + i 2 π · fn_________________________________________________________________[4.3982 + i (2 π fn + 4.4871)] [4.3982 + i (2 π fn
–4.4871)] = 0.11368

|

(25)

fn = 1

Then
A0 =

1
__________
0.11368(26)= 8.79640

Of course, equation (25) may be used to evaluate Hp(s) at any frequency other than f n. The phase of Hp (s) at f may beobtained by:
Ø (f) = tan-1(

N Im (s - rn)∏ -----------n=0 Re (s – rn)

)

- tan

-1

(

M

Im (s – pm)∏ ---------------m=0 Re (s – pm)

)

(27)

s=iπf

Where “Im” denotes the imaginary part of the argument and “Re” denotes the real part.
The symbol means everything to the left of the symbol is evaluated at the equation that follows it.

Example of Calculating Digital (FIR Filter) Stage Gain and Phase
For the FIR filter in the stage 3 example above, we have b1 = b0 = 0.50155 and Sd = 1.9938 at fs = 1 Hz. Using the form ofequation (9), the transfer function of this filter is
G (f) = Sd

L∑ bn z-n = Sd Hc (z)n=0= 1.9938 (0.50155 z0 + 0.50155 z-1)

(28)

So
Hc (z) = 0.50155 + 0.50155 (z-1)(29)

In order to evaluate Hc (z), we substitute z = e 2 π i f ∆t, where f is the frequency at which we wish to evaluate Hc (z) and∆t is the sample interval, defined as the inverse of the sample rate listed in Blockette [57] for the stage. Using f = 1 Hz
and ∆t =1/40 sec = 0.025 secs, we have
Hc (e2 π i (1) (.025) ) = 0.50155 (1 + e –2 π i (1) (.025) )(30)

Standard for the Exchange of Earthquake Data - Reference Manual • 167

Appendix

How did we find A0? To evaluate Hp (s) at f n = 1 Hz, we substitute for s the value s = iωn = i 2 π f n, and then calculate
the modulus of Hp (i 2 π f n):CAppendix C
Using the indentity
eiO = cos O + i sin O(31)

Equation (30) can be written

Hc = 0.50155 {1 + cos [-2 π (1) (.025)] + i sin [-2 π (1) (.025)]}

(32)

f=1

So the real part of Hc at f = 1 is

f = 1Re(Hc) = 0.50155 {1 + cos (-.05 π) } = 0.996925(33)

And the imaginary part of Hc at f = 1 is

f = 1Im(Hc) = 0.50155 { sin (-.05π } = 0.07846(34)

The magnitude of Hc at f = 1 is then
| Hc |f=1= {[Re(Hc)]f=12 +[Im (Hc)] f=12}1/2 = {(.996925)2 + (0.07846)2}1/2 =1.00000(35)

So we see that the coefficients b0 = b1 = 0.50155 chosen in the example really did normalize the magnitude of Hc (z) to avalue of 1.0 at f = 1 Hz.
How did we know to choose the coefficients to be b0 = b1 = 0.50155? If we express Hc (z) in equation (29) in its moregeneral form we have:
Hc (z) = b0 + b1 z-1(36)

Hc (e i 2 π f ∆ t )= b0 + b1 -i 2 π f ∆ t(37)

Hc f=1 = b0 + b1 cos [ -2 π f ∆ t] + sin [ -2 π f ∆ t]} f=1(38)

Equation (30) then becomes:and (32) becomes

If we then substitute in the actual FIR filter coefficient values of b0 = b1 = 1 from our example, we find that actual magnitude
of Hc at f = 1 isActual | Hc |f=1= 1.9938(39)

To normalize the coefficients bi so that the resulting Hc has a value of 1.0 at f = fs = 1 then, we must divide all of the bi by
this actual magnitude value in equation (39). These new values of bi are then used in Blockette [54]:New b0 =New b1 =Actual b0_______________

1.9938Actual b1_______________

1.9938= 0.50155(40)= 0.50155

Note that this step of normalization before entry of the coefficients into the SEED blockettes is equivalent to the introduction of the AO normalization constant for analog stages (AO is the inverse of | Hp (i 2 π f n) | ).

168 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix C
If we write equation (37) for L + 1 terms we have
Hc (e i 2 π f ∆ t )= b0 + b1 e -i 2 π f ∆ t + b2 e -i 2 π f ∆ t + … + bL e -i 2 π L f ∆ t(41)

If we now let f = 0 in equation (41), we see that the magnitude of Hc is just the sum of the coefficients:
Hc (e0 )= b0 + b1 + … bL

(42)

Appendix

CStandard for the Exchange of Earthquake Data - Reference Manual • 169

Appendix C

170 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix D

AppendixD

Appendix D:
The Data Description Language
Contributed by Ray Buland and Scott Halbert
Most existing data distribution formats limit data producers to creating only one of a few data formats. Producers must
contrive to produce data in the intended format, or convert data from the native format into the distribution format.
Conversion is generally unpalatable because it is costly to perform and results in a format that is either less compact orless precise than the original format. Also, some data problems can only be dealt with in the original recording format.
Unfortunately, adding new recording formats creates problems for data users as knowledge of the supported recording
formats is usually implied.
The data description language or DDL used with SEED lets the data producer use the native data format by describing
it in an unambiguous language that will ultimately drive a data parser and disassembler. The data producer may thenplace data directly into the SEED format with much less processing and manipulation.
Data Format Dictionary Blockette [30] uses the data description language. One blockette [30] must appear in the
Abbreviation Dictionary Control Header for each different data format appearing on the volume. As many different
formats may be defined as are needed. When defining the Channel ID Blockette [52], the unique number of the correct
Data Format Dictionary Blockette must be placed in the Data Format ID Code field.
The actual language is composed of several records, called keys. Each key describes some aspect of the language
for that family. Each family has its own arrangement and interpretation of keys. A key is made up of different fields
that contain the actual parser information. A field is typically a single letter code, followed by numeric parameters
determined by punctuation. Numeric parameters are always base 10. Braces (“{” and “}”) in the fields imply optional
sections. Two special codes specify exponentiation: #n denotes 2n, and %n denotes 10n. Keys are separated by tildes;
fields within keys are separated by spaces. White space should not be embedded within fields (see the listings ofBlockette [30] in Appendix E for sample data).
Standard for the Exchange of Earthquake Data - Reference Manual • 171

Appendix D
Several different data families are supported, including integer, gain ranged, integer differences compression, and text.
For each family, the keys are arranged in a logical sequence from the least specific to the most specific. For example,
for integer and gain ranged formats (families 0 and 1), key 1 describes the multiplexing of data from different channels.
Within this multiplexing scheme, key 2 describes how to extract and interpret the subsequent bits as a signed, fixed point
number. For integer formats, this value is the datum. For gain-ranged formats, it is the datum mantissa and keys 3 and4 describe how to acquire and interpret the characteristic. In both cases, it is implied that the rules for extracting andinterpreting the bit stream will be repeated until the number of samples specified in the Fixed Section of the Data Header
have been converted.
For the integer differences compression (family 50), key 1 gives instructions on accessing the integration constants, key 2
shows how to interpret the compression keys, and keys 3-m describe how to decompress data for all possible compression
key values. Optional key m+1 describes the grouping of frames (if necessary). In this case, keys 2-m provide a complete
description for interpreting all of the data packed into one compression frame. The interpretation of compression framesis then repeated until a group of frames is completed. The interpretation of groups of frames is repeated until all data
values have been decompressed. Note that multiplexing is not currently supported for compression formats.
The text formats (families 80, etc.), describe how to interpret free form text material embedded into a data record (suchas a console log). The interpretation is straightforward as shown below, primarily because the character codes used torepresent text are generally byte aligned and already have their own well-publicized international standards.
All of the binary data types (families 0, 1, and 50) rely on the fundamental operations of copying the next group of bits
into a temporary “working buffer” and then interpreting subsets of these bits as signed fixed point numbers. Because thisbasic set of operations is family and key independent, it will be described here. The description of the family dependent
keys will be given with each family. The fields defined for these extraction primitives fall into four groups: 1) copy andreorder bytes or bits from the input data stream into a temporary “working buffer”, 2) extract a subset of bits from theworking buffer with optional scaling and offset, 3) add sign information, and 4) miscellaneous operations. The extraction
primitive fields are common to all binary data type families and should not be redefined in these families.
By convention, all DDL fields operate on bytes and bits in big-endian order as described elsewhere in this manual. Thatis, bytes are encountered in big-endian or most significant byte first while bits are numbered in little endian order with theleast significant bit (LSB) in a word being numbered zero. Thus, big-endian bit numbering is only meaningful relative
to a particular word length, say in consecutive bits, in which case these bits are numbered 0, 1, 2, …, n+1 from the LSB
to the most significant bit (MSB). For the purpose of the copy/reorder operations, the binary data portion of a data record
is considered to be a stream of bytes that are processed in the order encountered. Alternatively, the byte stream can beconsidered to be a bit stream. In this case, the first bit in the bit stream will be the MSB of the first byte. Successive bits
are taken from the MSB to the LSB with the LSB of the first byte followed by the MSB of the second byte and so forth.
Note that bits in the bit stream are encountered in the opposite order from that implied by the big-endian bit numbering
within each byte. For example, if both the bytes and bits in the byte/bit streams were numbered consecutively from zero
we would have:
Bit Stream Bit Order
bit stream

byte stream

big-endian bit #

bit #
0

byte #
0

within each byte
7

1

0

6

:

:

:

7

0

0

8

1

7

9

1

6

:

:

:

172 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix D

Extraction Primitives
These primitives are used in the binary data families to interpret fixed point values from the data stream.

Copying/Reordering Primitives:
Wx{,n{,...}}

Wx{,n{,...}} - x bytes are copied from the input data stream:
Copy the next x 8-bit bytes from the input data stream into the working buffer, optionally reordering them as specified by the n’s. If the n’s are given, there must be x ofthem specified. The first n specifies which byte to take from the data stream first, thesecond n specifies which byte to take second, etc. The next x bytes in the byte stream
are numbered 0, 1, 2, ..., x-1 for the purpose of specifying the n’s.

Appendix

For example:

D

W4, 3, 2, 1, 0: Copy 4 bytes reversing them end-for-end in the working buffer. This
would reorder a little-endian longword into big-endian order.
W3: Copy 3 bytes into the working buffer without reordering. This is equivalent to
W3, 0, 1, 2

Bx{,t{,n{-m},...}}

Bx{,t{,n{-m},...}} - x bits are copied from the input data stream:
t=0: Groups of bits crossing byte boundaries take the remaining bits from the left sideof the next byte. This implies 68000 bit order (as described above).
t≠1: Reserved for future use.
Copy the next x bits from the input data stream into the working buffer, optionally
reordering groups of bits as specified by the “n-m’s”. If the “n-m” specifications are
given, they must reference each bit copied to the working buffer once and only once.
Omitting the “-m” implies “n-n”. Note that for the purpose of specifying the n-m’s,
the bits are numbered in big-endian (Motorola 68000) word order relative to the x-bit
long nibble just copied (i.e. the first bit copied will be bit number x-1 and the last will
be bit number 0.
For example:
B3, 0, 0-1, 2-3, 4-5: Copy six bits into the working buffer, last two bits first, middle
two bits next, and first two bits last.
B4, 0, 0, 1, 2, 3: Copy four bits into the working buffer in reverse order.
B5: Copy 5 bits into the working buffer without reordering. Equivalent to B5, 0 or
B5, 0, 4, 3, 2, 1, 0 or B5, 0, 4-4, 3-3, 2-2, 1-1, 0-0Standard for the Exchange of Earthquake Data - Reference Manual • 173

Appendix D

Extraction primitive:
D{n{-m}} {:b{:o:a}}D{n{-m}} {:b{:o:a}} - extract bits n-m from the working buffer to form unsigned
integer value k and then apply offset a and scale factors b as specified by code o.
If o=0, then add a to k and multiply the sum by b. If o=1, then multiply k by b andadd a. If b is negative, then divide by | b | instead of multiplying. Note that either theoffset or both the offset and the scale may be omitted. If n-m is omitted, extract allbits from the working buffer (and optionally apply the offset and scale). If -m is omitted, extract the “next” n bits from the working buffer from the “current position” (andoptionally apply the offset and scale.) By default these, “relative” mode extractions
are done in bit stream order beginning from the MSB of the working buffer. For moredetails, see the discussion following the Miscellaneous Primitives. The extraction
operator may be applied more than once to the same working buffer. If the extraction
operator is applied more than once to the working buffer in the same key, it is impliedthat all extracted (and possibly offset and scaled) values are to be added together. If
the extraction operator is applied more than once to the working buffer in successive
keys (or via the repeat operator), then each extracted value will be a distinct datum.
For example:
W1 D0-5: Copy one byte into the working buffer and extract the low order six bits as
an unsigned integer.
W2 D8-15:26:0:-65 D0-7:1:0:-65: Copy two bytes into the working buffer andextract each byte separately interpreting the pair such that two upper case alphabetic
ASCII characters becomes a two digit base 26 unsigned number.
B10 D: Copy 10 bits into the working buffer and extract them all. This could also be
written as B10 D0-9.
W1 D4 ~ D4: Copy one byte into the working buffer and extract two successive
4-bit quantities. This is equivalent to W1 D4-7 ~ D0-3 or to B4 D ~ B4 D. Note that
because the relative mode D operation works in bit stream order, it is a close analogueof the B operation.

Sign primitives:
C {t{,n}}C {t{,n}} — the number has a “complement” sign:
t = 1: use 1’s complementt = 2: use 2’s complementn = 1: the resultant number is always multiplied by -1
n ≠ 1 or omitted: the resultant number is left unchanged
Note that the C specification refers to the bits extracted by the preceding D specification. It only makes sense if the D specification includes no offset or scale that mightchange the sign bit.
For example
B12 D C2: Interpret the next 12 -bits as a 2’s complement number.

174 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix D

S b{,n}S b{,n} — the number has a sign bit:
if bit b is set: the number is negativen = 1: the resultant number is multiplied by -1
n ≠ 1 or omitted: the resultant number is left unchanged

For example:
W1 D0-6 S7: Interpret the next byte as a signed integer.
W1 D4-6:%1 D0-3 S7: Interpret the next byte as a two digit BCD integer using thehigh order bit as a sign bit for the sum of the two digits.

Ab

A b — the number uses a bias type sign:
The factor b is added to the formed number. (This number is almost always negative,
and is usually a power of 2 minus 1.)
The A specification will generally apply to the aggregate of all extraction operations
applied in the same key. Note that in some cases, the A specification can be redundantwith the D specification offset.
For example:
W1 D A-127: Interpret the next byte as an unsigned 8-bit integer with an offset of-127(yielding a range of [-127, 128]). Equivalent to W1 D:1:0:-127.
W1 D4-7%1 D0-3 A-49: Interpret the next byte as a two digit unsigned BCD integer
and then apply the sign bias (yielding a range of [-49, 50]).
A complete specification must include one copying/reordering primitive followed byat least one extraction specification. As noted above, if multiple extraction primitives
are given in one key, it is implied that the integers extracted should be added together.
It is possible for an extraction to reference bits copied into the working buffer in aprevious key. For example, in the gain-ranged family, the working buffer is filledwith both the characteristic and the mantissa during the mantissa extraction, while thecharacteristic extraction is performed in the next key. Another example would be tocopy/reorder enough bits to represent three fixed point numbers and then to extract
them in three successive keys or in one repeat operation. Only one of the possible
sign specification will usually be used in any one key and it will usually appear only
once. However, there are common cases in which no sign field is needed (e.g., an
unsigned integer or a sign offset included in the extraction field.

Miscellaneous Primitives:

Standard for the Exchange of Earthquake Data - Reference Manual • 175

Appendix

Note that the sign bit designated by the S specification is a bit in the working buffer.
The sign then applies to the aggregate of all extraction operations performed in thesame key. The sign bit itself should not be extracted in any D specification.

DAppendix D

Yx

Yx - repeat the following fields (to the end of the key) x times and interpret theresults as x distinct and successive data values. Repeating is never necessary but isvery convenient for complex specifications that would otherwise require many keys.
For example:
Y2 W1 D C2: Interpret the next two bytes as two 8-bit, twos complement, fixed
point numbers. This could also be written as W2 Y2 D8 C2

X

X - discard the result of the following operation. If a copy/reorder operation follows, discard the contents of the working buffer. If an extraction operation follows,
discard the result.
For example:
X W1: Skip one byte
X B2 B6 D C2: Skip two bits and then interpret the following six bits as a twos
complement, fixed point number. This could also be written as W1 X D2 D6 C2.

O{t}O{t} - specify the manner in which the relative mode extraction current position is
updated:t=0
t=1

or omitted use bit stream orderuse big-endian bit order

The O field affects the operation of all relative mode D fields that follow until another O field is encountered. O 0 is the default until the first O field in encountered.
In bit stream order, the current position defaults to the MSB following each copy/reorder operation and successive relative mode extractions proceed from MSB toward
LSB (from left to right). In big-endian bit order, the current position defaults to the
LSB following each copy/reorder operation and successive relative mode extractions
proceed from LSB toward MSB (from right to left).
For Example:
W1 Y2 D4 C2 is equivalent to W1 D4-7 C2 ~ D0-3 C2. While O1 W1 Y2 D4 C2 isequivalent to W1 D0-3 C2 ~ D4-7 C2.

176 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix D

Jx

Jx - set the relative mode extraction current position to big-endian bit number x
within the working buffer. Note that in bit stream order, the current position refers
to the high order bit of the next nibble extracted while in big-endian bit order it
refers to the low order bit of the next nibble extracted.
For example:
W1 J5 D4 C2 is equivalent to W1 D2-5 C2. This would also be equivalent to O1
W1 J2 D4 C2.

B6 D C2The same specification would be appropriate had the data words been packed into
successive 32-bit (long) words on a big-endian style machine. However, if the data
was packed into little-endian long words in bit stream order, the data is not describable at all unless blocks of 16 data words are first copied and byte reordered asfollows:
W12, 3, 2, 1, 0, 7, 6, 5, 4, 11, 10, 9, 8, Y16 D6 C2
In this case, the extraction of successive independent data values from one working buffer makes interpretation possible, while the repeat specification makes it
compact. If the same data was packed into long words in big-endian bit order, thespecification would be:
W12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 O1 Y16 D6 C2
Here the order instruction, supported by the byte reordering, makes the repeat possible. Finally, if the data was packed into big-endian 32 bit words in big-endian bit
order, then the specification would be:
W12, 8, 9, 10, 11, 4, 5, 6, 7, 0, 1, 2, 3, O1 Y16 D6 C2
Establishing and modifying the relative mode extraction current position also requires some additional discussion. The initial current position is set depending on
the bit orders selected as described above. This position is updated by each relativemode extraction as described. However, the current position could also be modified
by an absolute mode extraction (i.e. where n-m is specified). In bit stream order,
the new current position would be the bit just to the right of the bits first extracted(equivalent to issuing a Jn-1). In big-endian bit order, the new current position
would be the bit just to the left of the bits first extracted (equivalent to issuing aJm+1). The current position set operation is provided when the default or the resetting due to an absolute mode extraction is not what is desired. Note that the current
position could also be reset by discarding an absolute mode extraction except when
it is necessary to return to the default value.

Standard for the Exchange of Earthquake Data - Reference Manual • 177

Appendix

The repeat, discard, relative mode extract, and the relative mode extraction direction
and position fields provide a powerful facility in DDL for compactly describing nonbyte aligned data words packed into bytes under different assumptions. Althoughthese packings are natural under particular computer architectures, many of themwere previously not describable using DDL. For example, 6-bit twos complement
data words packed in bit stream order into successive bytes (on either a big-endianor little-endian style machine) can be described by:DAppendix D

Integer Format — Family 0
The integer format allows you to describe many kind of integer data. The multiplexing key fields described are also usedin the gain ranged family. This family has two keys:

Key 1

In integer format, key 1 describes sample multiplexing That is, samples, all recorded at the same time and sample rate, but from different channels appearing inthe same data record. We discourage sample multiplexing in the SEED format, but
you can describe it. If you use multiplexing, you must describe one sub-channel in
the Channel ID Blockette [52] for each multiplexed channel. “1” denotes the firstmultiplexed channel, “2” the second, and so on. Multiplexed samples will appear in
the data record in order of increasing sub-channel numbers.

Mx

M x — Multiplexed data code:x ≠ 0 or 1: data are multiplexed for x subchannels
x = 0 or 1: data are not multiplexed, and the data record contains data from only one
channelIx

I x — Data interleave (mandatory if more than 1 subchannel):x = 0: data are interleaved
x = 1: data are non-interleaved
When data are interleaved, the first sample of each sub-channel are written sequentially into the data record to form the first data frame. Then the second sample ofeach sub-channel are written sequentially to form the second data frame and so on.
Multiplexed, but non-interleaved data means that all samples from the first sub-channel for this record are written into the data record followed by all samples for thesecond sub-channel and so forth. The number of samples must always be an integer
multiple of the number of sub-channels. That is, there must be the same numberof samples for each sub-channel. Thus, if there are three multiplexed sub-channels
with 100 samples each , the number of samples shown in the Fixed Section of the
Header will be 300.

Lx

L x — Interleave size (optional):
x = number of bytes for each subchannel
Each subchannel begins on an x-byte boundary. (The x-byte block does not have to
be full.)
If not specified, SEED assumes that the first sample of the next subchannel exists
immediately after the last sample of the previous subchannel

178 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix D

Key 2

Key 2 describes the actual interpretation of the integer values using the extraction
primitives defined above.
The following examples illustrate the use of the integers format family.
Here is an example of DWWSSN data usage:
Key 1: M0
Key 2: W2 D0-15 C2 (or W2 D C2)

Key 1: M0
Key 2: W2 D0-3 D4-7:%1 D8-11:%2 D12-15:%3 or (W2 D4 D4:%1 D4:%2
D4:%3)

Gain Ranged Format — Family 1
Use this format to describe data stored as a fraction and multiplied by a gain factor. You can also use this format todescribe the native floating point systems of most computers. This family has four keys:

Key 1

This key is identical to key 1 of the integer type family.

Key 2

The second key describes how to form the mantissa, and is identical to key 2 of
the integer family except that the characteristic is copied into the working buffer
here, but is interpreted in key 3.

Key 3

Use this key to describe how to form the exponent (gain code). It, too, uses theextraction primitives. Note that the W or B fields are established in key 2 and cannot be set again in key 3.

Key 4This key describes the evaluation of the exponent. It uses the following fields todescribe the rules:

P gc:mlP gc:ml,... — describes the multiplier tables:
gc =a possible gain code value
ml > 0: If the gain code value extracted by key 3 equals gc, the mantissa extracted by key 2 is multiplied by the multiplier factor, ml.
ml < 0: If the gain code value extracted by key 3 equals, gc, the mantissa extracted by key 2 is divided by |ml|.
Specify any number of code/multiplier combinations. If a gain code is seen thatwas not defined, SEED assumes it to be a multiplier of 1.

Standard for the Exchange of Earthquake Data - Reference Manual • 179

Appendix

Here is a 4-nibble (2-byte) unsigned BCD format:

DAppendix DE b{:a{:m{:p}}}

E b{:a{:m{:p}}} — describes the exponent:b = the basea = an optional value added to the exponent (usually used as a bias in floating
point systems)
m = an optional value multiplying the sum of the exponent and a
p = an optional value added to the result of the operations just described
In other words:
sample = mantissa X bm(exponent+a)+p.

H

H — the mantissa has a hidden bit:
The number has been normalized such that the mantissa always has the high bit
set; it has therefore been implied without explicitly appearing in the data word.
Therefore, the hidden bit must be restored to the mantissa before applying thecharacteristic.

Z e{:m}Z e{:m} — the number system uses a “clean zero”:
Normalized floating point cannot normally express zero without extra information. If the exponent of the number being decoded is e, and optionally, the mantissa is equal to m, then this is a special code for exactly zero.
Here are some examples of the use of the gain ranged family:•

CDSN example (without multiplexing):
Key 1: M0
Key 2: W2 D0-13 A-8191
Key 3: D14-15
Key 4: P0:#0,1:#2,2:#4,3:#7•

SRO example (without multiplexing):
Key 1: M0
Key 2: W2 D0-11 C2
Key 3: D12-15
Key 4: E2:0:-1:10•

DEC F floating format:
Key 1: M0
Key 2: W4, 1, 0, 3, 2, D0-22 S31,0
Key 3: D23-30
Key 4: E2:-#7 H Z0

Integer Differences Compression — Family 50
This language describes some possible schemes for integer differences compression. While it cannot describe them all,it does describe those that resemble the Steim Compression Algorithm. This family uses 2 keys, plus a number of control
type keys (keys 3—n), which carry out the action required by the control code derived in key 2.
180 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix D

Key 1

The first key describes the integration constants and where they will be found:Pn

P n — determines which byte, relative to the start of the data, is the first byte of thenext integration constant.

Fn

F n — forward integration constant for the difference of order n:n = 1: the integration constant for the first differencen = 2: the integration constant for the second differenceRn

R n — the reverse integration constant for difference n; same as F above, exceptthat it is used primarily for error recovery and error checking.

Key 2

This key provides the description, location, and configuration of the control code
(compression key) bits for one compression frame. Note that a group of one ormore control codes are accessed in this key. Keys 3-m provide the interpretation for
the value of each key and result in the decompression of the data. The control codes
and the data associated with them make up one compression frame. Summation to
undo the differencing is implied.

Px

P x — the first control code section will be found x bytes after the start of data.
Use this to skip over header information that precedes data. The P specification isfollowed by a copying/ reordering primitive to place all of the control bits for thiscompression frame into the working buffer.

S n,l{,s}S n,l{,s} — the control code bits are n bits wide:l = 0: control codes start at the leftmost control code read left to rightl = 1: start at the rightmost code and read right to lefts ≠ 0: skip s control code positions before starting to extract control codesNx

N x — the number of usable control codes in this group, not including the codesskipped over by the command above.
Together the S and N specifications provide a description of all of the control codegroups for the compression frame at the same time. Note that S and N refer to thebits placed in the working buffer by the previous copying/reordering primitive. Operationally, the control code fields are interpreted one at a time in the order specified
in the S field. Each control code is interpreted as an unsigned integer value. The
keys 3-m provide instructions for decompressing data corresponding to each control
code value.

Keys 3-m
Tx

Select the key corresponding to each control code value derived above:
T x — describes how to decode data when a control code with the value x is encountered (derived by using key 2).

I

I - indirection. The next value extracted will be interpreted as unsigned sub-control
code.

Kx

Kx - analogous to Tx, but referring to the sub-control code value derived in theindirect specification.
Standard for the Exchange of Earthquake Data - Reference Manual • 181

Appendix

The fields that follow will describe interpreting this difference using the extraction
primitives until another F or R field is encountered. Note that, by default, the F1and R1 constants are data values while the F2 and R2 constants are first differences,etc.

DAppendix DNx

N x — the sequence identifier for the next difference to be decoded. One control
code or sub- control code value can result in unpacking many first differences. The
instructions for decoding the first difference value is preceded by N 0 to identify
it. The instructions for decoding the second difference value is preceded by N1,
etc. Note that if successive Nx fields in the same key use the same interpretation
specification, then they can all be replaced by a repeat operation.

Key m + 1

Optionally specify the action to take at the end of a block of compression frames.

Gx

Gx - a block is x compression frames long. The following extraction primitives
describe what action to take in collecting the block trailer information.
Notice the structure provided by DDL for the integer compression family: 1) data
records are divided into blocks, 2) blocks are divided into compression frames, 3)
compression frames are divided into a control code section and a data section. The
control code section may have many different control code values that are interpreted one at a time. Each control code results in the interpretation of one or moredifference values from the data section of the compression frame. The control code
section and all associated difference values in the data section define the lengthof a compression frame. Each compression frame is followed immediately byanother until a block is completed at which point the block trailer information mustbe skipped. One block follows another until all samples have been decompressed.
Note that the last block and compression frame may be incomplete. Control codes
after the control code in which the data is completed may be meaningless and theirassociated difference values may be missing. Note that not all family 50 formats use
the block structure concept making key n + 1 optional.
Some examples of the integer compression formats are:
The Steim 1 data format was originally described this way:
Key 1: F1 P4 W4 D0-31 C2 R1 P8 W4 D0-31 C2
Key 2: P0 W4 N15 S2,0,1
Key 3: T0 X N0 W4 D0-31 C2
Key 4: T1 N0 W1 D0-7 C2 N1 W1 D0-7 C2 N2 W1 D0-7 C2 N3 W1 D0-7 C2
Key 5: T2 N0 W2 D0-15 C2 N1 W2 D0-15 C2
Key 6: T3 N0 W4 D0-31 C2
The Steim 1 format could be described more compactly by using the repeat operation:
Key 1:
Key 2:
Key 3:
Key 4:Key 5:Key 6:F1 P4 W4 D C2 R1 P8 W4 D C2
P0 W4 N15 S2, 0, 1
T0 X W4
T1 Y4 W1 D C2
T2 Y2 W2 D C2
T3 N0 W4 D C2

182 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix D
The Steim 2 compression format can be described by:
F1 P4 W4 D C2 R1 P8 W4 D C2
P0 W4 N15 S2, 0,1
T0 X W4
T1 Y4 W1 D C2
T2 W4 I D2
K0 X D30
K1 N0 D30 C2
K2 Y2 D15 C2
K3 Y3 D10 C2
T3 W4 I D2
K0 Y5 D6 C2
K1 Y6 D5 C2
K2 X D2 Y7 D4 C2
K3 X D30

The USNSN data format looks like this:Key 1:
Key 2:
Key 3:
Key 4:Key 5:Key 6:Key 7:Key 8:Key 9:
Key 10:
Key 11:
Key 12:
Key 13:
Key 14:
Key 15:
Key 16:
Key 17:
Key 18:
Key 19:F1 P0 W4 D C2
P6 W2 N2 S4, 0, 0
T0 Y4 B4 D C2
T1 Y8 B4 D C2
T2 Y12 B4 D C2
T3 Y4 B6 D C2
T4 Y8 B6 D C2
T5 Y4 W1 D C2
T6 Y8 W1 D C2
T7 Y4 B10 D C2
T8 Y8 B10 D C2
T9 Y4 B12 D C2
T10 Y4 B14 D C2
T11 Y4 W2 D C2
T12 Y4 B20 D C2
T13 Y4 W3 D C2
T14 Y4 B28 D C2
T15 Y4 W4 D C2
G7 X W1

ASCII text — Family 80
You can also use the data records to record any ASCII text. Such data can come from console interaction by theoperator, from error logs, or from modem and telemetry transactions and audits. The number of samples in the fixeddata header simply refers to the number of text bytes used. The time of the data is approximately the time of the firstbytes in the record.
Use combinations of carriage returns (CR — ASCII 13) or line feeds (LF —ASCII 10) for the end-of-line characters.
We recommend using CRLF, LFCR, CR or LF. SEED allows nulls(NUL — ASCII 0), form feeds (FF —ASCII 12) andbells (BEL — ASCII 7), but we discourage using other control characters.

Non-ASCII text — Family 81
This data type is reserved for the non-ASCII text sequences of various languages.

Standard for the Exchange of Earthquake Data - Reference Manual • 183

Appendix

Key 1:
Key 2:
Key 3:
Key 4:Key 5:Key 6:Key 7:Key 8:Key 9:
Key 10:
Key 11:
Key 12:
Key 13:
Key 14:D

Appendix D

ASCII “Opaque” miniSEED - Family 90
When you only use the combination of Blockette 1000’s and Blockette 2000’s, use this data format identifier in theabbreviation dictionary, Blockette 30. These refer to data like GPS.

“Blockette” only - Family 91
When you only use the combination of Blockette 500’s and Blockette 2000’s, use this data format identifier in theabbreviation dictionary, Blockette 30. These refer to things like VCO corrections, and have channel names like ACE.

184 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix E

Appendix

E

Appendix E:
Sample Logical Volumes
Contributed by IRIS DMC

This appendix reproduces some actual blockettes from a sample SEED volume. It contains data for 5 stations in one
logical volume. Each logical volume is one day in length. The output has been edited to clarify the contents, where
two breaks in the sequence, for the sake of brevity, are noted in this output. The original SEED volume consisted of
92 discreet 4k records, but what is shown here are the first 10 logical 4k records, followed by logical records 52 and 53
which illustrates Blockette [61] and Blockette [62] placement, and finally the Blockette [74] time span, in record 92. It
shows the relative placement of volume index control headers, abbreviation dictionary control headers, station control
headers and time span control headers. The left-most fields of this output, to the left of the colon character, are thelocical record numbers and the Blockette type, followed by the length of the line following.
The records listed display the important information. “Type” refers to the blockette type, and “len” is the length of theblockette (including the type and length fields).
We hope this reproduction will clearly illustrate most details of the SEED implementation, and that it will assist yourorganization in developing SEED reading and writing utilities.

Standard for the Exchange of Earthquake Data - Reference Manual • 185

Appendix E
LOGICAL VOLUME 1 BEGINS HERE
logrec 1 type ‘V ‘
type 010 len 0096 : 02.4122004,366,23:27:49.2843~2005,002,00:29:41.2906~2005,214,09:17:00.0000~IRIS DMC~SEED~
type 011 len 0065 : 005ANMO 000003CMB 000052RAYN 000061UNM 000081VNDA 000088
type 012 len 0063 : 00012004,366,23:27:49.2843~2005,002,00:29:41.2906~000092
logrec 2 type ‘A ‘
type 030 len 0237 : Steim2 Integer Compression Format~000105014F1 P4 W4 D C2 R1 P8 W4 D C2~P0 W4 N15 S2,0,1~T0 X W4~T1 Y: 4 W1 D C2~T2 W4 I D2~K0 X D30~K1 N0 D30 C2~K2 Y2 D15 C2~K3 Y3 D10 C2~T3 W4 I D2~K0 Y5 D6 C2~K1 Y6 D5: C2~K2 X D2 Y7 D4 C2~K3 X D30~
type 030 len 0232 : Steim Integer Compression Format~000205006F1 P4 W4 D0-31 C2 R1 P8 W4 D0-31 C2~P0 W4 N15 S2,0,1~T0 X: N0 W4 D0-31 C2~T1 N0 W1 D0-7 C2 N1 W1 D0-7 C2 N2 W1 D0-7 C2 N3 W1 D0-7 C2~T2 N0 W2 D0-15 C2 N1 W2 D0: -15 C2~T3 N0 W4 D0-31 C2~type 030 len 0028 : Console Log~000308000
type 030 len 0238 : Steim-2 Integer Compression Format~000405014F1 P4 W4 D C2 R1 P8 W4 D C2~P0 W4 N15 S2,0,1~T0 X W4~T1: Y4 W1 D C2~T2 W4 I D2~K0 X D30~K1 N0 D30 C2~K2 Y2 D15 C2~K3 Y3 D10 C2~T3 W4 I D2~K0 Y5 D6 C2~K1 Y6 D
: 5 C2~K2 X D2 Y7 D4 C2~K3 X D30~
type 031 len 0069 : 0001CChannel has high frequency cultural background noise.~000
type 031 len 0032 : 0002CChannel is down.~000
type 031 len 0047 : 0003CChannel has occasional spiking.~000
type 031 len 0025 : 0004CTEST DATA~000
type 031 len 0050 : 0005CSeismometer mass is against stops.~000
type 031 len 0067 : 0006CChannel exibits high levels of low frequency noise.~000
type 031 len 0044 : 0007CInvalid instrument response.~000
type 031 len 0057 : 0008CTime uncertain; error less than 1 second.~000
type 031 len 0059 : 0009SError on sensors poles may reach 2 percent.~000
type 031 len 0057 : 0010SSensors responses contain nominal values.~000
type 031 len 0031 : 0011STime Uncertain.~000
type 033 len 0055 : 001(GSN) Global Seismograph Network (IRIS/USGS)~
type 033 len 0048 : 002Geotech KS-54000 Borehole Seismometer~
type 033 len 0047 : 003Guralp CMG3-T Seismometer (borehole)~
type 033 len 0043 : 004IU Paroscientific Microbarograph~
type 033 len 0041 : 005Vaisala PTA 427 Microbarograph~
type 033 len 0059 : 006Crossbow Technology 3-axis fluxgate magnetometer~
type 033 len 0045 : 007Kinemetrics FBA-23 Low-Gain Sensor~
type 033 len 0053 : 008Handar model 425A wind direction indicator~
type 033 len 0049 : 009Handar model 425A wind speed indicator~
type 033 len 0054 : 010(GSN) Global Seismograph Network (IRIS/IDA)~
type 033 len 0040 : 011Streckeisen STS-2 Seismometer~
type 033 len 0034 : 012Console Log - Error Log~
type 033 len 0019 : 013GEOSCOPE~
type 033 len 0027 : 014STRECKEISEN STS1~
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Standard for the Exchange of Earthquake Data - Reference Manual • 187

Appendix

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188 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix E: 0E+00 2.68281E-03 0.00000E+00-2.88342E-03 0.00000E+00-5.03823E-03 0.00000E+00 1.32459E-03 0.00000E+0: 0 7.31891E-03 0.00000E+00 1.80785E-03 0.00000E+00-8.72253E-03 0.00000E+00-6.49492E-03 0.00000E+00 8.
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…………… A break in the record sequence is arbitrarily set here, so that logical records 52 and 53 can be shown………………
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Standard for the Exchange of Earthquake Data - Reference Manual • 189

Appendix

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type 058 len 0035 : 01 2.41685E+03 1.50000E-0100
type 054 len 0024 : D0200100200000000
type 057 len 0051 : 025.1200E+030000100000 6.1520E-03-6.2500E-03
type 058 len 0035 : 02 4.19075E+05 1.50000E-0100
type 061 len 0487 : 03FIR_QDP380900616S1~C0020020032-1.1132811E-03-1.0080021E-03-1.3528608E-03-1.7304537E-03-2.0841800E: 03-2.3853772E-03-2.6095563E-03-2.7335226E-03-2.7331619E-03-2.5847244E-03-2.2641171E-03-1.7484681E-03: -1.0140331E-03-3.5168174E-05 1.2378203E-03 3.1598317E-03 6.9994498E-03 9.0995990E-03 1.2542364E-02 1: .6312301E-02 2.0263240E-02 2.4317261E-02 2.8405109E-02 3.2460414E-02 3.6414284E-02 4.0198740E-02 4.3: 745048E-02 4.6987325E-02 4.9857292E-02 5.2279573E-02 5.4113958E-02 5.4390285E-02
type 057 len 0051 : 035.1200E+030001600000 6.1520E-03-6.2500E-03
type 058 len 0035 : 03 1.01477E+00 0.00000E+0000
type 061 len 0543 : 04FIR_QDP380900616S2~C0020020036 1.5048734E-04 3.0592416E-04 4.4294869E-04 3.8711738E-04-4.7378693E: 05-9.7077183E-04-2.3031710E-03-3.7063768E-03-4.6250466E-03-4.4648014E-03-2.8698447E-03 7.0086089E-06: 3.3851995E-03 6.0035284E-03 6.5509360E-03 4.2599519E-03-5.7602394E-04-6.4341645E-03-1.0921375E-02-1: .1636412E-02-7.2651519E-03 1.5372745E-03 1.1933105E-02 1.9615697E-02 2.0351628E-02 1.1868029E-02-4.6: 436903E-03-2.4112536E-02-3.8638294E-02-3.9849922E-02-2.1868395E-02 1.6161226E-02 6.8962365E-02 1.260: 0332E-01 1.7422935E-01 2.0183417E-01
type 057 len 0051 : 043.2000E+020000400000 9.8611E-02-1.0000E-01
type 058 len 0035 : 04 9.78112E-01 0.00000E+0000
type 061 len 0487 : 05FIR_QDP380900616S3~C0020020032 2.8804955E-04 1.5531398E-03 2.9823051E-03 2.5171447E-03-5.0292682E: 04-2.8120584E-03-8.0870837E-04 3.2154298E-03 2.7126600E-03-2.9155032E-03-5.0942907E-03 1.3393303E-03: 7.4003437E-03 1.8279653E-03-8.8195829E-03-6.5671932E-03 8.3860857E-03 1.2426868E-02-5.1297885E-03-1: .8486859E-02-1.7923677E-03 2.3360418E-02 1.3047730E-02-2.5170945E-02-2.9313477E-02 2.1266930E-02 5.2: 189898E-02-6.6151735E-03-8.8353522E-02-3.6606237E-02 1.8627329E-01 4.0376449E-01
type 057 len 0051 : 058.0000E+010000200000 3.9375E-01-4.0000E-01
type 058 len 0035 : 05 1.01113E+00 0.00000E+0000
type 058 len 0035 : 00 1.01649E+09 1.50000E-0100
type 052 len 0120 : BHN 018~003012+38.034550-120.386510+0697.0002.0000.0+00.00004124.0000E+012.0000E-030000~2004,16: 7,00:00:00~~N
type 053 len 0334 : A01003001 3.94764E+03 1.50000E-01002 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.0: 0000E+00 0.00000E+00 0.00000E+00004-1.23412E-02 1.23415E-02 0.00000E+00 0.00000E+00-1.23412E-02-1.23: 415E-02 0.00000E+00 0.00000E+00-3.91757E+01 4.91234E+01 0.00000E+00 0.00000E+00-3.91757E+01-4.91234E: +01 0.00000E+00 0.00000E+00
type 058 len 0035 : 01 2.27515E+03 1.50000E-0100
type 054 len 0024 : D0200100200000000
type 057 len 0051 : 025.1200E+030000100000 6.1520E-03-6.2500E-03
type 058 len 0035 : 02 3.95638E+05 1.50000E-0100
type 061 len 0487 : 03FIR_QDP380900616S1~C0020020032-1.1132811E-03-1.0080021E-03-1.3528608E-03-1.7304537E-03-2.0841800E: 03-2.3853772E-03-2.6095563E-03-2.7335226E-03-2.7331619E-03-2.5847244E-03-2.2641171E-03-1.7484681E-03: -1.0140331E-03-3.5168174E-05 1.2378203E-03 3.1598317E-03 6.9994498E-03 9.0995990E-03 1.2542364E-02 1: .6312301E-02 2.0263240E-02 2.4317261E-02 2.8405109E-02 3.2460414E-02 3.6414284E-02 4.0198740E-02 4.3: 745048E-02 4.6987325E-02 4.9857292E-02 5.2279573E-02 5.4113958E-02 5.4390285E-02
type 057 len 0051 : 035.1200E+030001600000 6.1520E-03-6.2500E-03
type 058 len 0035 : 03 1.01477E+00 0.00000E+0000
type 061 len 0543 : 04FIR_QDP380900616S2~C0020020036 1.5048734E-04 3.0592416E-04 4.4294869E-04 3.8711738E-04-4.7378693E: 05-9.7077183E-04-2.3031710E-03-3.7063768E-03-4.6250466E-03-4.4648014E-03-2.8698447E-03 7.0086089E-06: 3.3851995E-03 6.0035284E-03 6.5509360E-03 4.2599519E-03-5.7602394E-04-6.4341645E-03-1.0921375E-02-1: .1636412E-02-7.2651519E-03 1.5372745E-03 1.1933105E-02 1.9615697E-02 2.0351628E-02 1.1
logrec 53 type ‘S*’E

Appendix E
type 057 len 0051 : 058.0000E+010000200000 3.9375E-01-4.0000E-01
type 058 len 0035 : 05 1.01113E+00 0.00000E+0000
type 058 len 0035 : 00 9.32278E+08 1.50000E-0100
type 052 len 0120 : LDS 020~004012+38.034550-120.386510+0697.0002.0000.0+00.00004121.0000E+001.0000E-040000~2004,16: 7,00:00:00~~N
type 062 len 0129 : P01004001MA 0.00000E+00 5.00000E-01-7.85200E+00 7.85200E+00 1.00000E-02002 0.00000E+00 0.00000E+00 3: .92600E-04 0.00000E+00
type 054 len 0024 : D0200100200000000
type 057 len 0051 : 025.1200E+030000100000 6.1520E-03-6.2500E-03
type 058 len 0035 : 02 4.30717E+05 1.00000E-0200
type 061 len 0487 : 03FIR_QDP380900616S1~C0020020032-1.1132811E-03-1.0080021E-03-1.3528608E-03-1.7304537E-03-2.0841800E: 03-2.3853772E-03-2.6095563E-03-2.7335226E-03-2.7331619E-03-2.5847244E-03-2.2641171E-03-1.7484681E-03: -1.0140331E-03-3.5168174E-05 1.2378203E-03 3.1598317E-03 6.9994498E-03 9.0995990E-03 1.2542364E-02 1: .6312301E-02 2.0263240E-02 2.4317261E-02 2.8405109E-02 3.2460414E-02 3.6414284E-02 4.0198740E-02 4.3: 745048E-02 4.6987325E-02 4.9857292E-02 5.2279573E-02 5.4113958E-02 5.
…………………… Another arbitrary break in the sequence is made here, for the sake of brevity……………………..
logrec 92 type ‘T ‘
type 070 len 0054 : P2004,366,23:27:49.2843~2005,002,00:29:41.2906~
type 074 len 0084 : ANMO 00BH12004,366,23:59:32.0108~000094012005,001,00:00:06.2108~00009401000IU
type 074 len 0084 : ANMO 00BH12005,001,00:00:00.0108~000095012005,001,23:59:59.9604~00038704000IU
type 074 len 0084 : ANMO 10BH12004,366,23:59:56.2483~000388012005,001,00:00:07.2983~00038801000IU
type 074 len 0084 : ANMO 10BH12005,001,00:00:00.0233~000389012005,001,23:59:59.9979~00126904000IU
type 074 len 0084 : ANMO 00BH22004,366,23:59:42.5608~001270012005,001,00:00:16.7608~00127001000IU
type 074 len 0084 : ANMO 00BH22005,001,00:00:00.0108~001271012005,001,23:59:59.9604~00156004000IU
type 074 len 0084 : ANMO 10BH22004,366,23:59:54.3233~001561012005,001,00:00:05.4983~00156101000IU
type 074 len 0084 : ANMO 10BH22005,001,00:00:00.0233~001562012005,001,23:59:59.9979~00242204000IU
type 074 len 0084 : ANMO 00BHZ2004,366,23:59:33.1108~002423012005,001,00:00:06.6108~00242301000IU
type 074 len 0084 : ANMO 00BHZ2005,001,00:00:00.0108~002424012005,001,23:59:59.9604~00272504000IU
type 074 len 0084 : ANMO 10BHZ2004,366,23:59:56.6483~002726012005,001,00:00:07.3233~00272601000IU
type 074 len 0084 : ANMO 10BHZ2005,001,00:00:00.0233~002727012005,001,23:59:59.9979~00362104000IU
type 074 len 0084 : ANMO 00LDO2004,366,23:57:31.0000~003622012005,001,00:09:31.0000~00362201000IU
type 074 len 0084 : ANMO 00LDO2005,001,00:00:00.0000~003623012005,001,02:42:57.0000~00362504000IU
type 074 len 0084 : ANMO 00LDO2005,001,02:43:16.0000~003626012005,001,03:46:07.0000~00362604000IU
type 074 len 0084 : ANMO 00LDO2005,001,03:46:26.0000~003627012005,001,04:28:13.0000~00362704000IU
type 074 len 0084 : ANMO 00LDO2005,001,04:28:30.0000~003628012005,001,19:52:35.0000~00363604000IU
type 074 len 0084 : ANMO 00LDO2005,001,19:52:54.0000~003637012005,001,20:40:47.0000~00363704000IU
type 074 len 0084 : ANMO 00LDO2005,001,20:41:04.0000~003638012005,001,20:53:01.0000~00363804000IU
type 074 len 0084 : ANMO 00LDO2005,001,20:53:20.0000~003639012005,001,23:59:59.0000~00364004000IU
type 074 len 0084 : ANMO 10LDO2004,366,23:55:56.0358~003641012005,001,00:01:45.0358~00364101000IU
type 074 len 0084 : ANMO 10LDO2005,001,00:00:00.0358~003642012005,001,23:59:59.0354~00367104000IU
type 074 len 0084 : ANMO 00LFZ2004,366,23:59:59.0358~003672012005,001,00:11:59.0358~00367201000IU
type 074 len 0084 : ANMO 00LFZ2005,001,00:00:00.0359~003673012005,001,23:59:59.0354~00368704000IU
type 074 len 0084 : ANMO 00LH12004,366,23:58:21.4858~003688012005,001,00:02:41.4858~00368801000IU
type 074 len 0084 : ANMO 00LH12005,001,00:00:00.4858~003689012005,001,23:59:59.4854~00372804000IU
type 074 len 0084 : ANMO 10LH12004,366,23:56:54.4858~003729012005,001,00:00:20.4858~00372901000IU
type 074 len 0084 : ANMO 10LH12005,001,00:00:00.4858~003730012005,001,23:59:59.4854~00377704000IU
type 074 len 0084 : ANMO 00LH22004,366,23:58:02.4858~003778012005,001,00:02:33.4858~00377801000IU
type 074 len 0084 : ANMO 00LH22005,001,00:00:00.4858~003779012005,001,23:59:59.4854~00381804000IU
type 074 len 0084 : ANMO 10LH22004,366,23:59:56.4858~003819012005,001,00:03:21.4858~00381901000IU
type 074 len 0084 : ANMO 10LH22005,001,00:00:00.4858~003820012005,001,23:59:59.4854~00386704000IU
type 074 len 0084 : ANMO 00LHZ2004,366,23:59:54.4858~003868012005,001,00:03:49.4858~00386801000IU
type 074 len 0084 : ANMO 00LHZ2005,001,00:00:00.4858~003869012005,001,23:59:59.4854~00391104000IU
type 074 len 0084 : ANMO 10LHZ2004,366,23:56:49.4858~003912012005,001,00:00:14.4858~00391201000IU
type 074 len 0084 : ANMO 10LHZ2005,001,00:00:00.4858~003913012005,001,23:59:59.4854~00396104000IU
type 074 len 0084 : ANMO 20LNE2004,366,23:59:58.0358~003962012005,001,00:11:58.0358~00396201000IU
type 074 len 0084 : ANMO 20LNE2005,001,00:00:00.0359~003963012005,001,23:59:59.0354~00397704000IU
type 074 len 0084 : ANMO 20LNN2004,366,23:59:58.0358~003978012005,001,00:11:58.0358~00397801000IU
type 074 len 0084 : ANMO 20LNN2005,001,00:00:00.0359~003979012005,001,23:59:59.0354~00399304000IU
type 074 len 0084 : ANMO 20LNZ2004,366,23:59:59.0358~003994012005,001,00:11:59.0358~00399401000IU
type 074 len 0084 : ANMO 20LNZ2005,001,00:00:00.0359~003995012005,001,23:59:59.0354~00400904000IU
type 074 len 0084 : ANMO 00LWD2004,366,23:58:51.0000~004010012005,001,00:08:24.0000~00401001000IU
type 074 len 0084 : ANMO 00LWD2005,001,00:00:00.0000~004011012005,001,19:51:00.0000~00402704000IU
type 074 len 0084 : ANMO 00LWD2005,001,19:51:17.0000~004028012005,001,23:59:59.0000~00403104000IU
type 074 len 0084 : ANMO 00LWS2004,366,23:54:15.0000~004032012005,001,00:06:08.0000~00403201000IU
type 074 len 0084 : ANMO 00LWS2005,001,00:00:00.0000~004033012005,001,19:51:59.0000~00404604000IU
type 074 len 0084 : ANMO 00LWS2005,001,19:52:16.0000~004047012005,001,23:59:59.0000~00404904000IU
logrec 93 type ‘T ‘
type 074 len 0084 : CMB BHE2005,001,00:00:00.0107~004050012005,001,23:59:59.9858~00481304000BK
type 074 len 0084 : CMB BHN2005,001,00:00:00.0107~004814012005,001,23:59:59.9858~00551604000BK
type 074 len 0084 : CMB BHZ2005,001,00:00:00.0107~005517012005,001,23:59:59.9858~00612604000BK
type 074 len 0084 : CMB LDS2005,001,00:00:00.6482~006127012005,001,23:59:59.6483~00616004000BK
type 074 len 0084 : CMB LEP2005,001,00:00:00.4501~006161012005,001,23:59:59.4501~00617604000BK
type 074 len 0084 : CMB LHE2005,001,00:00:00.6482~006177012005,001,23:59:59.6483~00621004000BK
type 074 len 0084 : CMB LHN2005,001,00:00:00.6482~006211012005,001,23:59:59.6483~00624404000BK
type 074 len 0084 : CMB LHZ2005,001,00:00:00.6482~006245012005,001,23:59:59.6483~00627904000BK
type 074 len 0084 : CMB LKS2005,001,00:00:00.6482~006280012005,001,23:59:59.6483~00630404000BK
type 074 len 0084 : RAYN 00BHE2005,001,00:00:00.0072~006305012005,001,00:00:04.4072~00630504000II
type 074 len 0084 : RAYN 00BHE2005,001,00:00:06.5244~006306012005,001,23:59:59.9826~00677504000II
type 074 len 0084 : RAYN 10BHE2005,001,00:00:00.0198~006776012005,001,00:00:05.3698~00677604000II
type 074 len 0084 : RAYN 10BHE2005,001,00:00:05.3894~006777012005,001,23:59:59.9976~00769804000II
type 074 len 0084 : RAYN 00BHN2005,001,00:00:00.0072~007699012005,001,00:00:04.4072~00769904000II
type 074 len 0084 : RAYN 00BHN2005,001,00:00:06.5244~007700012005,001,23:59:59.9826~00816804000II
type 074 len 0084 : RAYN 10BHN2005,001,00:00:00.0198~008169012005,001,00:00:05.3698~00816904000II
type 074 len 0084 : RAYN 10BHN2005,001,00:00:05.3894~008170012005,001,18:07:41.3706~00886704000II
type 074 len 0084 : RAYN 10BHN2005,001,18:07:53.3927~008868012005,001,23:59:59.9947~00909204000II
type 074 len 0084 : RAYN 00BHZ2005,001,00:00:00.0072~009093012005,001,00:00:04.5072~00909304000II
type 074 len 0084 : RAYN 00BHZ2005,001,00:00:06.6244~009094012005,001,23:59:59.9826~00956604000II
type 074 len 0084 : RAYN 10BHZ2005,001,00:00:00.0198~009567012005,001,00:00:05.4198~00956704000II
type 074 len 0084 : RAYN 10BHZ2005,001,00:00:05.4394~009568012005,001,23:59:59.9976~01048904000II
type 074 len 0084 : RAYN 00LHE2005,001,00:00:00.4423~010490012005,001,00:00:03.4423~01049004000II
type 074 len 0084 : RAYN 00LHE2005,001,00:00:26.4744~010491012005,001,23:59:59.4846~01053704000II
type 074 len 0084 : RAYN 00LHN2005,001,00:00:00.4423~010538012005,001,00:00:03.4423~01053804000II
type 074 len 0084 : RAYN 00LHN2005,001,00:00:26.4744~010539012005,001,23:59:59.4846~01058504000II
type 074 len 0084 : RAYN 00LHZ2005,001,00:00:00.5423~010586012005,001,00:00:03.5423~01058604000II
type 074 len 0084 : RAYN 00LHZ2005,001,00:00:26.5744~010587012005,001,23:59:59.5846~01063304000II
type 074 len 0084 : RAYN 00LNE2005,001,00:00:00.7348~010634012005,001,23:59:59.7392~01065704000II
type 074 len 0084 : RAYN 00LNN2005,001,00:00:00.7348~010658012005,001,23:59:59.7392~01068104000II
type 074 len 0084 : RAYN 00LNZ2005,001,00:00:00.7348~010682012005,001,23:59:59.7392~01070504000II

190 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix E
type 074 len 0084 : UNM BHE2004,366,23:57:49.5844~010706012005,001,00:00:36.6844~01070604000G
type 074 len 0084 : UNM BHE2005,001,00:00:36.7344~010707012005,002,00:01:55.6906~01117004000G
type 074 len 0084 : UNM BHN2004,366,23:59:43.6344~011171012005,001,00:02:28.2844~01117104000G
type 074 len 0084 : UNM BHN2005,001,00:02:28.3344~011172012005,002,00:01:59.4906~01164004000G
type 074 len 0084 : UNM BHZ2004,366,23:58:24.4844~011641012005,001,00:01:09.8344~01164104000G
type 074 len 0084 : UNM BHZ2005,001,00:01:09.8844~011642012005,002,00:02:02.5406~01210704000G
type 074 len 0084 : UNM LHE2004,366,23:27:49.2843~012108012005,001,00:03:27.2843~01210804000G
type 074 len 0084 : UNM LHE2005,001,00:03:28.2844~012109012005,002,00:20:54.2906~01214904000G
type 074 len 0084 : UNM LHN2004,366,23:31:15.2843~012150012005,001,00:06:20.2843~01215004000G
type 074 len 0084 : UNM LHN2005,001,00:06:21.2844~012151012005,002,00:29:41.2906~01219204000G
type 074 len 0084 : UNM LHZ2004,366,23:32:29.2843~012193012005,001,00:14:56.2843~01219304000G
type 074 len 0084 : UNM LHZ2005,001,00:14:57.2844~012194012005,002,00:23:29.2906~01222804000G
type 074 len 0084 : VNDA 00BHE2005,001,00:00:00.0000~012229012005,001,23:59:59.9750~01298604000GT
type 074 len 0084 : VNDA 00BHN2005,001,00:00:00.0000~012987012005,001,23:59:59.9750~01373404000GT
type 074 len 0084 : VNDA 00BHZ2005,001,00:00:00.0000~013735012005,001,23:59:59.9750~01455804000GT

Example Log Channel Blockette (header) Summary
logrec 2 type ‘A ‘
type 030 len 0067 : ASCII Quanterra Baler14 log files, State of Health~000208000
type 033 len 0055 : 002Streckeisen STS-2/Quanterra 330 Linear Phase~logrec 3 type ‘S ‘
type 050 len 0100 : C16A -77.124400+167.898400+2.00001000Iceberg C16 Station A~0013210102003,291,00:00:00~~NXV
type 052 len 0120 : LOG 002~000000-77.124400+167.898400+0002.0000.0000.0+00.00002120.0000E+000.0000E+000000~2003,291,00:43:50~~N
Example Log Channel Fixed Section of Data Header Contentslogrec type ‘D ‘
STATION
C16A

LOCATIONCHANNEL NETWORK TIME
LOG
XV
2003,353,032406.6200# samples in record: 4021
sample_rate: 0
multiplier: 1
activity flags:
I/O and clock flags:
data quality flags:# of blockettes: 1time correction: 0
begin data offset: 56
begin blkette offset: 48
BLOCKETTE 1000:
encoding format: ASCII text (val:0)
word order: big endian word orderdata record length: 12
reserved: 0

Example of an ACE Channel, which has blockette 500:
logrec 2 type ‘A ‘
type 030 len 0038 : Quanterra ACE Channel~000109100
STATION
C16A

LOCATIONCHANNEL NETWORK TIME
ACE
XV
2003,355,000000.0000 [1]# samples in record: 0
sample_rate: 0
multiplier: 1
activity flags:
I/O and clock flags:
data quality flags:# of blockettes: 2time correction: 0
begin data offset: 0
begin blkette offset: 48
BLOCKETTE 1000:
encoding format: ASCII text (val:0)
word order: big endian word orderdata record length: 12
reserved: 0
BLOCKETTE 500:
VCO correction: 35.9863

Standard for the Exchange of Earthquake Data - Reference Manual • 191

Appendix

Examples of Log and Opaque Data Records

EAppendix E
Example of an “Opaque” Channel, which has blockette 2000’s:
logrec type ‘D ‘
STATION
C16A

LOCATIONCHANNEL NETWORK TIME
OCF
XV
2003,355,03:08:01.0000 :# samples in record 0
sample_rate 0
multiplier 1
activity flags
I/O and clock flags
data quality flags# of blockettes 7
time correction 0
begin data offset 0
begin blkette offset 48
BLOCKETTE 1000
encoding format ASCII text (val:0)
word order big endian word orderdata record length 12
reserved 0
BLOCKETTE 2000
blockette length 178
offset to data 18
record number 0
data word order 1
opaque data flags (0) Record oriented (val:0)(1) May contain multiple data records (val:0)(2-3) Record completely contained (val:0)(4-5) Not file oriented (val:0)
number header fields 1
opaque data header L~

192 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix F

Contributed by Tim Ahern
Some abbreviation dictionaries in a SEED volume contain fields that reference other blockettes. Here is a list:
Blockette

Field

Blockette Name

References
Blockette

Field

Blockette Name

31
41
41
43
43
44
44
45
45
46
46
49
49
50
51
52
52
52
52
53
53
54
54
55
55
56
56
59
60
60
60
60
60
60
60

6
6
7
6
7
6
7
5
6
5
6
6
7
10
5
6
8
9
16
5
6
5
6
4
5
4
5
5
6
6
6
6
6
6
6

Comment Description
FIR Dictionary
FIR Dictionary
Response (Poles & Zeros) Dictionary
Response (Poles & Zeros) Dictionary
Response (Coefficients) Dictionary
Response (Coefficients) Dictionary
Response List Dictionary
Response List Dictionary
Generic Response Dictionary
Generic Response Dictionary
Response (Polynomial) Dictionary
Response (Polynomial) Dictionary
Station Identifier
Station Comment
Channel Identifier
Channel Identifier
Channel Identifier
Channel Identifier
Response (Poles & Zeros)
Response (Poles & Zeros)
Response (Coefficients)
Response (Coefficients
Response List
Response List
Generic Response
Generic Response
Channel Comment
Response Reference
Response Reference
Response Reference
Response Reference
Response Reference
Response Reference
Response Reference

34
34
34
34
34
34
34
34
34
34
34
34
34
33
31
33
34
34
30
34
34
34
34
34
34
34
34
31
41
43
44
45
46
47
48

3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3

Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Generic Abbreviation
Comment Description
Generic Abbreviation
Units Abbreviations
Units Abbreviations
Data Format Dictionary
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Comment Description
FIR Dictionary
Response (Poles & Zeros) Dictionary
Response (Coefficients) Dictionary
Response List Dictionary
Generic Response Dictionary
Decimation Dictionary
Channel Sensitivity/Gain Dictionary

Standard for the Exchange of Earthquake Data - Reference Manual • 193

Appendix

Appendix F:
Cross Reference for Fields inAbbreviation Dictionaries

FAppendix F
61
61
71
71
71
72
400

6
7
4
11

11+pX3

11
5

FIR Response
FIR Response
Hypocenter Information
Hypocenter Information
Hypocenter Information
Event Phases
Beam

34
34
32
32
32
32
35

3
3
3
3
3
3
3

Units Abbreviations
Units Abbreviations
Cited Source Dictionary
Cited Source Dictionary
Cited Source Dictionary
Cited Source Dictionary
Beam Configuration

For example, field 4 of the Hypocenter Info Blockette [71] references field 3 of the Cited Source Dictionary Blockette [32].
NOTE: Field 11+pX3 of the Hypocenter Info Blockette [71] is the last field in the blockette’s group. In the equation, p =field 8 of the blockette.
Some fields are referenced by more than one blockette:
Blockette

Field

Blockette Name

30
31
31
32
32
32
32
33
33
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
34
35
41
43
44
45
46
47
48

4
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3

Data Format Dictionary
Comment Description
Comment Description
Cited Source Dictionary
Cited Source Dictionary
Cited Source Dictionary
Cited Source Dictionary
Generic Abbreviation
Generic Abbreviation
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Units Abbreviations
Beam Configuration
FIR Dictionary
Response (Poles & Zeros) Dictionary
Response (Coefficients) Dictionary
Response List Dictionary
Generic Response Dictionary
Decimation Dictionary
Channel Sensitivity/Gain Dictionary

Is Referenced
by Blockette
52
51
59
71
71
71
72
50
52
31
41
41
43
43
44
44
45
45
46
46
52
52
53
53
54
54
55
55
56
56
61
61
400
60
60
60
60
60
60
60

Field

Blockette Name

16
5
5
4
11

Channel Identifier
Station Identifier
Channel Comment
Hypocenter Information
Hypocenter Information
Hypocenter Information
Event Phase Blockette
Station Identifier
Channel identifier
Comment Description
FIR Dictionary
FIR Dictionary
Response (Poles & Zeros) Dictionary
Response (Poles & Zeros) Dictionary
Response (Coefficients) Dictionary
Response (Coefficients) Dictionary
Response List Dictionary
Response List Dictionary
Generic Response Dictionary
Generic Response Dictionary
Channel Identifier
Channel Identifier
Response (Poles & Zeros)
Response (Poles & Zeros)
Response (Coefficients)
Response (Coefficients)
Response List
Response List
Generic Response
Generic Response
FIR Response
FIR Response
Beam
Response Reference
Response Reference
Response Reference
Response Reference
Response Reference
Response Reference
Response Reference

11+pX3

11
10
6
6
6
7
6
7
6
7
5
6
5
6
8
9
5
6
5
6
4
5
4
5
6
7
5
6
6
6
6
6
6
6

194 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix G

AppendixG

Appendix G:
Data Only SEED Volumes(Mini-SEED)
Contributed by Tim Ahern

The SEED format consists of Volume Control Headers, Abbreviation Control Headers, Station Control Headers, Time
Span Control Headers and finally Data Records. At the 1991 FDSN meeting in Vienna, Austria the concept of Dataless
SEED volumes was introduced and accepted. In December of 1992, the data-only complement to the Dataless SEED,
called Mini-SEED, was adopted and incorporated into the Version 2.3 specification. The structure of SEED data
records is simple, straightforward, and much simpler to understand than the control header structure of SEED. Some
data loggers offer SEED data records as a method of transferring waveform information. The term Data Only SEED
Volumes (Mini-SEED) has come to be used to identify SEED data records without any of the associated control header
information. Data Only and Dataless SEED volumes are to a certain extent the two parts of a complete SEED volume.
Only Time Span Control Headers are not included in either of these components, however Time Span Control Headers
can be derived from the Data Only SEED.
The SEED format standard is defined by the FDSN Working Group on Data Exchange. This working group has recognized the need to more specifically address the definition and use of Data Only SEED as a data exchange format. Data
Only SEED also has potential for use as a data analysis format. In the SEED format, much of the information needed
to specify the time series in the data records is in the SEED control headers. In fact, the fixed header portion of the
SEED format does not contain information about the organization of the data in the Data Only SEED records. Missing
information includes
1) specification of the data encoding format as normally specified in the DDL2) ‘the word order of the data record as either big endian or little endian.
3) the data record length
Standard for the Exchange of Earthquake Data - Reference Manual • 195

Appendix G
With the inclusion of the above information, the Data Only format can be used to completely decode the time series
information in the data records. Of course response information and some other information remains unavailable and theneed to retain full SEED volume production is encouraged.
The Data Only SEED data blockette has been designed to include the needed information. The data blockette is defined
as follows;[1000] Data Only SEED Blockette (8 bytes)
Note
1

Field name
Blockette type - 1000

Type
B

Length2

3

Encoding Format

B

1

2
4
5
6

Next blockette’s byte number
Word order

Data Record Length
Reserved

B
B
B
B

Mask or Flags

2
1
1
1

1

UWORD : Blockette type (1000): Data Only SEED2

UWORD : Byte number of next blockette. (Calculate this as the byte offset from the beginning of the logical record- including the fixed section of the data header; use 0 if no more blockettes will follow.)

3

BYTE : A code indicating the encoding format. This number is assigned by the FDSN Data Exchange Working
Group. To request that a new format be included contact the FDSN through the FDSN Archive at the IRIS DataManagement Center. To be supported in Data Only SEED, the data format must be expressible in SEED DDL. A
list of valid codes at the time of publication follows.
CODES 0-9
0
1
2
3
4
5

GENERALASCII text, byte order as specified in field 4
16 bit integers
24 bit integers
32 bit integers
IEEE floating point
IEEE Double precision floating point

CODES 10 - 29
10
11
12
13
14
15
16
17
18
19

FDSN Networks
STEIM (1) Compression
STEIM (2) Compression
GEOSCOPE Multiplexed Format 24 bit integer
GEOSCOPE Multiplexed Format 16 bit gain ranged, 3 bit exponent
GEOSCOPE Multiplexed Format 16 bit gain ranged, 4 bit exponent
US National Network compression
CDSN 16 bit gain ranged
Graefenberg 16 bit gain ranged
IPG - Strasbourg 16 bit gain ranged
STEIM (3) Compression

CODES 30 - 49
30
31
32
33

OLDER NETWORKSSRO Format
HGLP Format
DWWSSN Gain Ranged Format
RSTN 16 bit gain ranged

4

The byte swapping order for 16 bit and 32 bit words. A 0 indicates little endian order and a 1 indicates big endian
word order. See fields 11 and 12 of blockette 50.

5

The exponent (as a power of two) of the record length for these data. The data record can be as small as 256 bytes
and, in Data Only SEED format as large as 2 raised to the 256 power.

196 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix G

Additional Considerations in Data Only SEEDAny SEED data blockette can be included in the Data Only SEED format except those that refer to abbreviation
dictionary blockettes. For instance blockette 100 is permitted but blockette 400 is not.

2

The Data Only SEED data blockette can be present in a full SEED volume. In this case the values in the Data
Only SEED blockette take precedence over values in the SEED control headers.

3

When combining Data Only SEED data records with a Dataless SEED volume to produce a SEED volume, Time
Span Control Headers must be constructed. The only other major consideration is that if the Data Only SEED
record length exceeds the maximum length of 4096 bytes allowed in SEED, then the longer Data Only SEED
data records must be blocked into data records of valid length.

4Much of the necessary information needed to make the time series decipherable is already well defined in the
fixed section of the data header. These fields remain unchanged.

5Each data record must have blockette 1000.

6

The order of the fixed section of the data header must be the same as field 4 of blockette 1000 implies.

The IRIS SEED reader, RDSEED, is now capable of processing Dataless SEED volumes and Data Only SEED volumes
simultaneously and therefore may provide a method of reading Mini- SEED data records that do not include blockette
1000.

Standard for the Exchange of Earthquake Data - Reference Manual • 197

Appendix

1

GAppendix G

198 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix H

Appendix

H

Appendix H
This appendix was intentionally left blank.

Standard for the Exchange of Earthquake Data - Reference Manual • 199

Appendix H

200 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix I

AppendixI
H

Appendix I
This appendix was intentionally left blank.

Standard for the Exchange of Earthquake Data - Reference Manual • 201

Appendix IH

202 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix J

AppendixJ
H

Appendix J:
Network Codes
Contributed by Tim Ahern

The following network codes are assigned by the FDSN archive (IRIS DMC) to provide uniqueness to seismological
data streams, and was introduced in v2.3. This is now a required field when submitting data to an archive.
You can register for a Network Code at the URL:
http://www.fdsn.org/getcode.html
The first line provides the network code and the network name. The second line of each entry provides the nameof the network operator or responsible organization. For example:
AA			

Anchorage Strong Motion Network

			Geophysical Institute, University of Alaska, Fairbanks

The current list of Network Codes is available online at:
http://www.iris.edu/stations/networks.txt

Standard for the Exchange of Earthquake Data - Reference Manual • 203

Appendix JH
Appendix

204 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix K

Appendix

K

Appendix K: Flinn-Engdahl Seismic
Regions
Code

Seismic Region

Description

1

1

Central Alaska

21Southern Alaska

3

1Bering Sea

4

1

Komandorsky Islands Region

5

1

Near Islands, Aleutians Islands

6

1

Rat Islands, Aleutian Islands

71

Andreanof Islands, Aleutian Islands

81

Pribilof Islands

91

Fox Islands, Aleutians Islands

101

Unimak Island Region

11

1Bristol Bay

121

Alaska Peninsula

13

1

Kodiak Island Region

14

1

Kenai Peninsula, Alaska

15

1

Gulf of Alaska

16

1

Aleutian Islands Region171South of Alaska

182Southern Yukon Territory, Canada

192Southeastern Alaska

20

2

Off Coast of Southeastern Alaska

21

2West Vancouver Island

22

2

Queen Charlotte Islands Region

23

2

British Columbia

24

2

Alberta Province, Canada

25

2

Vancouver Island Region

26

2

Off Coast of Washington

27

2

Near Coast of Washington

28

2

Washington-Oregon Border Region

29

2

Washington

30

3

Off Coast of Oregon

Standard for the Exchange of Earthquake Data - Reference Manual • 205

Appendix K
31

3

Near Coast of Oregon

88

7

Dominican Republic Region

32

3

Oregon89

7

Mona Passage

33

3Western Idaho

90

7

Puerto Rico Region

34

3

Off Coast of Northern California

91

7

Virgin Islands

35

3

Near Coast of Northern California

92

7

Leeward Islands
Belize36

3

Northern California

93

7

37

3

Nevada94

7

Caribbean Sea

38

3

Off Coast of California

95

7

Windward Islands

39

3

Central California

96

7

Near North Coast of Columbia

40

3

California-Nevada Border Region

97

7

Near Coast of Venezuela

41

3Southern Nevada

98

7

Trinidad

42

3Western Arizona

99

7

Northern Columbia

433Southern California

100

7Lake Maracaibo
Venezuela

44

3

California-Arizona Border Region

101

7

45

3

California-Mexico Border Region

102

7

Near West Coast of Columbia

46

3

W. Arizona-Mexico Border Region

103

8

Columbia

47

4

Off W. Coast of Baja California

104

8

Off Coast of Ecuador

48

4

Baja California

105

8Near Coast of Ecuador

49

4

Gulf of California

1068Columbia-Ecuador Border Region

50

4Northwestern California

107

8

Ecuador

51

4

Off Coast of Central Mexico

108

8

Off Coast of Northern Peru

52

4

Near Coast of Central Mexico

109

8

Near Coast of Northern Peru

53

5

Revilla Gigedo Islands Region

1108Peru-Ecuador Border Region

54

5

Off Coast of Jalisco, Mexico

111

8

Northern Peru

55

5Near Coast of Jalisco, Mexico

1128Peru-Brazil Border Region

56

5Near Coast of Michoacan, Mexico

113

8

Western Brazil

57

5

Michoacan, Mexico

114

8

Off Coast of Peru

58

5Near Coast of Guerrero, Mexico

115

8Near Coast of Peru

59

5

Guerrero, Mexico

116

8

Peru

60

5

Oaxaca, Mexico

117

8

Southern Peru

61

5

Chiapas, Mexico

118

8Peru-Bolivia Border Region

62

5

Mexico-Guatemala Border Region

119

8

Northern Bolivia

63

5

Off Coast of Mexico

120

8

Bolivia64

5

Off Coast of Michoacan, Mexico

121

8

Off Coast of Northern Chile

65

5

Off Coast of Guerrero. Mexico

122

8

Near Coast of Northern Chile

66

5Near Coast of Oaxaca

123

8Northern Chile

67

5

Off Coast of Oaxaca

124

8Chile-Bolivia Border Region

68

5

Off Coast of Chiapas

125

8Southern Bolivia

69

5

Near Coast Chiapas

126

8Paraguay

70

5

Guatemala127

8

Chile-Argentina Border Region

71

5

Near Coast of Guatemala

128

8Jujuy Province, Argentina

72

6

Honduras

129

8

Salta Province, Argentina

73

6

El Salvador

130

8Catamarca Province, Argentina

74

6

Near Coast of Nicaragua

1318

Tucuman Province, Argentina

75

6

Nicaragua1328Santiago Del Estero Province, Argentina

76

6

Off Coast of Central America

133

8Northeastern Argentina

77

6

Off Coast of Costa Rica

134

8

Off Coast of Central Chile

78

6

Costa Rica

135

8Near Coast of Central Chile

79

6

North of Panama

136

8Central Chile

80

6Panama-Costa Rica Border Region

137

8

San Juan Province, Argentina

81

6

Panama138

8

La Rioja Province, Argentina
Mendoza Province, Argentina

82

6Panama-Columbia Border Region

139

8

83

6

South of Panama

140

8

San Luis Province, Argentina

84

7

Yucatan Peninsula

141

8

Cordoba Province, Argentina

85

7

Cuba Region

142

8

Uruguay

86

7

Jamaica Region

143

9

Off Coast of Southern Chile

87

7

Haiti Region

144

9Near Coast of Southern Chile

206 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix K
145

9South Chile-Argentina Border Region

202

16

Papua New Guinea

146

10

Argentina

203

16

Bismarck Sea

147

10

Tierra del Fuego

204

16

Aroe Islands Region

148

10

Falkland Islands Region

205

16

Near South Coast of West Irian

149

10

Drake Passage

206

16

Near South Coast of Papua, New Guinea
East Papua, New Guinea Region

10

Scotia Sea

207

16

151

10

South Georgia Island Region

208

16

Arafura Sea

152

10

South Georgia Rise

209

17

West Caroline Islands

153

10

South Sandwich Islands Region

210

17

South of Mariana Islands

154

10

South Shetland Islands Region

211

18

South of Honshu, Japan

155

10

Antarctic Peninsula

212

18

Bonin Islands Region

156

10

Southwestern Atlantic Ocean

213

18

Volcano Islands Region

157

10

Weddell Sea

214

18

West of Mariana Islands

158

11

Off West Coast of North Island New Zealand

215

18

Mariana Islands Region

159

11

North Island, New Zealand

216

18

Mariana Islands

160

11

Off East Coast of North Island, New Zealand

217

19

Kamchatka

161

11

Off West Coast of South Island, New Zealand

218

19

Near East Coast of Kamchatka

162

11

South Island, New Zealand

219

19

Off East Coast of Kamchatka

163

11

Cook Straight, New Zealand

220

19

Northwest of Kuril Islands

164

11

Off East Coast of South Island, New Zealand

221

19

Kuril Islands

165

11

North of MacQuarie Island

222

19

Kuril Islands Region

166

11

Aukland Islands Region

223

19

Eastern Sea of Japan

167

11

MacQuarie Islands Region

224

19

Hokkaido, Japan Region

168

11

South of New Zealand

225

19

Off Coast of Hokkaido, Japan

169

12

Samoa Islands Region

226

19

Near West Coast of Honshu, Japan
Honshu, Japan

170

12

Samoa Islands

227

19

171

12

South of Fiji Islands

228

19

Near East Coast of Honshu, Japan

172

12

West of Tonga Islands

229

19

Off East Coast of Honshu, Japan

173

12

Tonga Islands

230

19

Near South Coast of Honshu, Japan

174

12

Tonga Islands Region

231

20

South Korea

175

12

South of Tonga Islands

232

20

Southern Honshu, Japan

176

12

North of New Zealand

233

20

Near South Coast of Southern Honshu

177

12

Kermadec Islands Region

234

20

East China Sea

178

12

Kermadec Islands

235

20

Kyushu, Japan

179

12

South of Kermadec Islands

236

20

Shikoku, Japan

180

13

North of Fiji Islands

237

20

Southeast of Shikoku, Japan

181

13

Fiji Islands Region

238

20

Ryukyu Islands

182

13

Fiji Islands

239

20

Ryukyu Islands Region

183

14

Santa Cruz Islands Region

240

20

East of Ryukyu Islands

184

14

Santa Cruz Islands

241

20

Philippine Sea

185

14

Vanuatu Islands Region

242

21

Near Southeastern Coast of China

186

14

Vanuatu Islands

243

21

Taiwan Region

187

14

New Caledonia

244

21

Taiwan188

14

Loyalty Islands

245

21

Northeast of Taiwan

189

14

Loyalty Islands Region

246

21

Southwestern Ryukyu Islands
Southeast of Taiwan

190

15

New Ireland Region

247

21

191

15

North of Solomon Islands

248

22

Philippine Islands Region

192

15

New Britain Region

249

22

Luzon, Philippine Islands

193

15

Solomon Islands

250

22

Mindoro, Philippine Islands

194

15

Dentrecasteaux Islands Region

251

22

Samar, Philippine Islands

195

15

Solomon Islands Region

252

22

Palawan, Philippine Islands

196

16

West Irian Region

253

22

Sulu Sea

197

16

Near North Coast of West Irian

254

22

Panay, Philippine Islands

198

16

Papua, New Guinea Region

255

22

Cebu, Philippine Islands

199

16

Admiralty Islands Region

256

22

Leyte, Philippine Islands

200

16

Near North Coast of Papua, New Guinea

257

22

Negros, Philippine Islands

201

16

West Irian

258

22

Sulu Archipelago

Standard for the Exchange of Earthquake Data - Reference Manual • 207

Appendix

150

KAppendix K
259

22

Mindanao, Philippine Islands

316

26

Bangladesh

260

22

East of Philippine Islands

317

26

Eastern India

261

23

Kalimantan

318

26

Yunnan Province, China

262

23

Celebes Sea

319

26

Bay of Bengal

263

23

Talaud Islands

320

27

Kirghiz-Xinjiang Border Region
Southern Xinjiang, China

264

23

North of Halmahera

321

27

265

23

Minahassa Peninsula

322

27

Gansu Province China

266

23

Molucca Passage

323

27

Northern China

267

23

Halmahera

324

27

Kashmir-Xinjiang Border Region

268

23

Sulawesi

325

27

Qinghai Province, China

269

23

Molucca Sea

326

28

Central USSR
Lake Baikal Region

270

23

Ceram Sea

327

28

271

23

Buru

328

28

East of Lake Baikal

272

23

Ceram

329

28

Eastern Kazakh SSR

273

24

Southwest of Sumatera

330

28

Alma-Ata Region

274

24

Southern Sumatera

331

28

Kazakh-Xinjiang Border Region

275

24

Java Sea

332

28

Northern Xinjiang Region

276

24

Sunda Strait

333

28

USSR-Mongolia Border Region

277

24

Java

334

28

Mongolia

278

24Bali Sea

335

29

Ural Mountains Region

279

24

Flores Sea

336

29

Western Kazakh SSR

280

24

Banda Sea

337

29

Eastern Caucasus

281

24

Tanimbar Islands Region

338

29

Caspian Sea

282

24

South of Java

339

29

Uzbek SSR

283

24

Bali Island Region

340

29

Turkmen SSR
Iran-USSR Border Region

284

24

South of Bali Island

341

29

285

24

Sumbawa Island Region

342

29

Turkmen-Afghanistan Border Region

286

24

Flores Island Region

343

29

Turkey-Iran Border Region

287

24

Sumba Island region

344

29

North West Iran-USSR Border Region

288

24

Savu Sea

345

29

Northwestern Iran

289

24

Timor

346

29

Iran-Iraq Border Region
Western Iran

290

24

Timor Sea

347

29

291

24

South of Sumbawa Island

348

29

Iran

292

24

South of Sumba Island

349

29

Northwestern Afghanistan

293

24

South of Timor

350

29

Southwestern Afghanistan

294

25

Burma-India Border Region

351

29

Eastern Arabian Peninsula

295

25

Burma-Bangladesh Border Region

352

29

Persian Gulf

296

25

Burma

353

29

Southern Iran

297

25

Burma-China Border Region

354

29

Pakistan298

25South Burma

355

29

Gulf of Oman

299

25

Southeast Asia

356

29

Near Coast of Pakistan

300

25

Hainan Island

357

30

Southwestern USSR

301

25

South China Sea

358

30

Romania

302

26

Eastern Kashmir

359

30

Bulgaria

303

26

Kashmir-India Border Region

360

30

Black Sea

304

26

Kashmir-Tibet Border Region

361

30

Crimea Region

305

26

Tibet-India Border Region

362

30

Western Caucasus

306

26

Tibet

363

30

Greece-Bulgaria Border Region

307

26

Sichuan Province, China

364

30

Greece308

26

Northern India

365

30

Aegean Sea

309

26

Nepal-India Border Region

366

30

TurkeyTurkey-USSR Border Region

310

26

Nepal

367

30

311

26

Sikkim368

30

Southern Greece

312

26

Bhutan369

30

Dodecanese Islands

313

26

India - China Border Region

370

30

Crete

314

26

India

371

30

Eastern Mediterranean Sea

315

26

India-Bangladesh Border Region

372

30

Cyprus208 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix K
30

Dead Sea Region

430

33

South of Africa

374

30

Jordan - Syria Region

431

33

Prince Edward Islands Region

375

30

Iraq

432

33

Crozet Islands Region

376

31

Portugal433

33

Kerguelen Islands Region

377

31

Spain

434

33

Amsterdam-Naturaliste Ridge

378

31

Pyrenees435

33Southeast Indian Rise

379

31

Near South Coast of France

436

33

Kerguelen-Gaussberg Rise

380

31

Corsica

437

33South of Australia

381

31

Central Italy

438

34

Saskatchewan Province, Canada

382

31

Adriatic Sea

439

34

Manitoba Province, Canada

383

31

Yugoslavia

440

34

Hudson Bay
Ontario384

31West of Gibraltar

441

34

385

31

Strait of Gibraltar

442

34

Hudson Strait Region

386

31

Balearic Islands

443

34

Northern Quebec

387

31

Western Mediterranean Sea

444

34

Davis Strait

388

31

Sardinia

445

34

Labrador389

31

Tyrrhenian Sea

446

34

East of Labrador

390

31

Southern Italy

447

34

Southern Quebec

391

31

Albania

448

34

Gaspe Peninsula

392

31

Greece-Albania Border Region

449

34

Eastern Quebec

393

31

Madeira Islands Region

450

34

Anticosti Island, Canada

394

31

Canary Islands Region

451

34

New Brunswick

395

31

Morocco452

34

Nova Scotia

396

31

Algeria453

34

Prince Edward Island, Canada

397

31

Tunisia454

34

Gulf of Saint Lawrence

398

31

Sicily455

34

Newfoundland

399

31

Ionian Sea

456

34

Montana400

31Mediterranean Sea

457

34

Eastern Idaho

401

31

Near Coast of Libya

458

34

Hebgen Lake Region

402

32

North Atlantic Ocean

459

34

Yellowstone National Park, Wyoming

403

32

North Atlantic Ridge

460

34

Wyoming404

32

Azores Islands Region

461

34

North Dakota

405

32

Azores Islands

462

34

South Dakota

406

32

Central Mid-Atlantic Ridge

463

34

Nebraska407

32

North of Ascension Islands

464

34

Minnesota

408

32

Ascension Islands Region

465

34

Iowa

409

32

South Atlantic Ocean

466

34

Wisconsin

410

32

South Atlantic Ridge

467

34

Illinois

411

32

Tristan Da Cunha Region

468

34

Michigan412

32

Bouvet Island Region

469

34

Indiana413

32Southwest of Africa

470

34

Southern Ontario

414

32

Southeastern Atlantic Ocean

471

34

Ohio

415

33

Eastern Gulf of Aden

472

34

New York

416

33

Socotra Region

473

34

Pennsylvania

417

33

Arabian Sea

474

34

Northern New England

418

33

Laccadive Islands Region

475

34

Maine

419

33

Northeastern Somalia

476

34

Southern New England

420

33

North Indian Ocean

477

34

Gulf of Maine

421

33

Carlsberg Ridge

478

34

Utah

422

33

Maldive Islands Region

479

34

Colorado423

33

Laccadive Sea

480

34

KansasIowa-Missouri Border Region

424

33

Sri Lanka

481

34

425

33

South Indian Ocean

482

34

Missouri-Kansas Border Region

426

33

Chagos Archipelago Region

483

34

Missouri427

33

Mascarene Islands Region

484

34

Missouri-Arkansas Border Region

428

33

Atlantic-Indian Rise

485

34

Eastern Missouri

429

33

Mid-Indian Rise

486

34

New Madrid, Missouri Region

Standard for the Exchange of Earthquake Data - Reference Manual • 209

Appendix

373

KAppendix K
487

34

Cape Girardeau, Missouri Region

544

36

Switzerland

488

34

Southern Illinois

545

36

Northern Italy

489

34

Southern Indiana

546

36

Austria490

34

Kentucky

547

36

Czechoslovakia

491

34

West Virginia

548

36

Poland492

34

Virginia549

36

Hungary493

34

Chesapeake Bay Region

550

37

Northwest Africa
Southern Algeria

494

34

New Jersey

551

37

495

34

Eastern Arizona

552

37

Libya

496

34

New Mexico

553

37

Arab Republic of Egypt

497

34

Texas Panhandle Region

554

37

Red Sea498

34West Texas

555

37

Western Arabian Peninsula

499

34

Oklahoma

556

37

Central Africa

500

34

Central Texas

557

37

Sudan

501

34

Arkansas-Oklahoma Border Region

558

37

Ethiopia

502

34

Arkansas559

37

Western Gulf of Aden

503

34

Louisiana-Texas Border Region

560

37

Northwestern Somalia

504

34

Louisiana

561

37

Off South Coast of Northwest Africa

505

34

Mississippi

562

37

Cameroon

506

34

Tennessee563

37

Equatorial Guinea

507

34

Alabama

564

37

Central African Republic

508

34

Western Florida

565

37

Gabon

509

34

Georgia566

37

Congo Republic

510

34

Florida-Georgia Border Region

567

37

Zaire Republic

511

34

South Carolina

568

37

Uganda512

34

North Carolina

569

37

Lake Victoria Region

513

34

Off East Coast of United States

570

37

Kenya

514

34

Florida Peninsula

571

37

Southern Somalia

515

34

Bahama Islands

572

37

Lake Tanganyika Region

516

34

Eastern Arizona-Mexico Border Region

573

37

Tanzania

517

34

Mexico-New Mexico Border Region

574

37

Northwest of Madagascar

518

34

Texas-Mexico Border Region

575

37

Angola519

34Southern Texas

576

37

Zambia520

34

Texas Gulf Coast

577

37

Malawi

521

34

Chihuahua, Mexico

578

37

Namibia
Botswana Republic

522

34

Northern Mexico

579

37

523

34

Central Mexico

580

37

Zimbabwe524

34

Jalisco, Mexico

581

37

Mozambique

525

34

Vera Cruz, Mexico

582

37

Mozambique Channel

526

34

Gulf of Mexico

583

37

Malagasay Republic

527

34

Gulf of Campeche

584

37

Republic of South Africa

528

35

Brazil585

37

Lesotho529

35

Guyana586

37

Swaziland

530

35

Suriname

587

37

Off Coast of South Africa

531

35

French Guiana

588

38

Northwest of Australia

532

35

Eire

589

38

West of Australia

533

36

United Kingdom

590

38

Western Australia

534

36

North Sea

591

38

Northern Territory, Australia

535

36

Southern Norway

592

38

South Australia

536

36

Sweden593

38

Gulf of Carpenteria

537

36

Baltic Sea

594

38

Queensland, Australia

538

36

France595

38

Coral Sea

539

36

Bay of Biscay

596

38

South of Solomon Islands

540

36

Netherlands

597

38

New Caledonia Region

541

36

Belgium

598

38Southwest of Australia

542

36

Denmark

599

38

Off South Coast of Australia

543

36

Germany

600

38

Near South Coast of Australia

210 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix K
601

38

New South Wales, Australia

658

41

Northeastern China

602

38

Victoria, Australia

659

41

North Korea

603

38

Near South East Coast of Australia

660

41

Sea of Japan

604

38

Near East Coast of Australia

661

41

Near East Coast of Eastern USSR

605

38

East of Australia

662

41

Sakhalin Island
Sea of Okhotsk

606

38

Norfolk Island Region

663

41

607

38

Northwest of New Zealand

664

41

Eastern China

608

38

Bass Strait

665

41

Yellow Sea

38

Tasmania Region

666

41

Off Coast of Eastern China

610

38

Southeast of Australia

667

42

North of New Siberian Islands

611

39

North Pacific Ocean

668

42

New Siberian Islands

612

39

Hawaii Region

669

42

East Siberian Sea

613

39

Hawaii

670

42

Near North Coast of Eastern Siberia

614

39

Caroline Islands Region

671

42

Eastern Siberia

615

39

Marshall Islands Region

672

42

Chukchi Sea

616

39

Eniwetok Atoll Region

673

42

Bering Strait

617

39

Bikini Atoll Region

674

42

Saint Lawrence Island Region

618

39

Gilbert Islands

675

42

Beaufort Sea

619

39

Johnston Island Region

676

42

Alaska620

39Line Islands Region

677

42

Northern Yukon Territory, Canada

621

39

Palmyra Island Region

678

42

Queen Elizabeth Islands
Northwest Territories, Canada

622

39

Christmas Island Region

679

42

623

39

Ellice Islands Region

680

42

Western Greenland

624

39

Phoenix Islands Region

681

42

Baffin Bay

625

39

Tekelau Islands Region

682

42

Baffin Island Region
Southeast Central Pacific Ocean

626

39

Northern Cook Islands

683

43

627

39

Cook Islands Region

684

43

Easter Island Cordillera

628

39

Society Islands Region

685

43

Easter Island Region

629

39

Tubuai Islands Region

686

43

West Chile Rise

630

39

Marquesas Islands Region

687

43

Juan Fernandez Islands Region

631

39

Tuamotu Archipelago Region

688

43

East of North Island, New Zealand

632

39

South Pacific Ocean

689

43

Chatham Islands Region

633

40

Lomonosov Ridge

690

43

South of Chatham Islands

634

40

Arctic Ocean

691

43

South of Pacific Cordillera

635

40

Near North Coast of Greenland

692

43

Southern Pacific Ocean

636

40

Eastern Greenland

693

44

East Central Pacific Ocean

637

40

Iceland Region

694

44

Northern Easter Island Cordillera

638

40

Iceland695

44West of Galapagos Islands

639

40

Jan Mayen Island region

696

44

Galapagos Islands Region

640

40

Greenland Sea

697

44

Galapagos Islands

641

40

North of Svalbard

698

44

Southwest of Galapagos Islands

642

40

Norwegian Sea

699

44

Southeast of Galapagos Islands

643

40

Svalbard Region

700

45

South of Tasmania

644

40

North of Franz Josef Land

701

45

West of MacQuarie Island

645

40

Franz Josef Land

702

45

Balleny Islands Region
Andaman Islands Region

646

40

Northern Norway

703

46

647

40

Barents Sea

704

46

Nicobar Islands Region

648

40

Novaya Zemlya

705

46

Off West Coast of Northern Sumatera

649

40

Kara Sea

706

46

Northern Sumatera

650

40

Near Coast of Western Siberia

707

46

Malay Peninsula

651

40

North of Severnaya Zemlya

708

46

Gulf of Thailand

652

40

Severnaya Zemlya

709

47

Afghanistan

653

40

Near Coast of Central Zemlya

710

47

Pakistan

654

40

East of Severnaya Zemlya

711

47

Southwestern Kashmir

655

40

Laptev Sea

712

47

India-Pakistan Border Region

656

41

Eastern USSR

713

48

Central Kazakh SSR

657

41

East USSR-North East China Border Region

714

48

Southeastern Uzbek SSR

Standard for the Exchange of Earthquake Data - Reference Manual • 211

Appendix

609

KAppendix K
715

48

Tajik SSR

716

48

Kirghiz SSR

717

48

Afghanistan-USSR Border Region

718

48

Hindu Kush Region

719

48

Tajik-Xinjiang Border Region

720

48

Northwestern Kashmir

721

49

Finland722

49

Norway-USSR Border Region

723

49

Finland-USSR Border Region

724

49

European USSR

725

49

Western Siberia

726

49

Central Siberia

727

49

Victoria Land, Antarctica

728

50

Ross Sea

729

50

Antarctica

212 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix L

Appendix

L

Appendix L: FDSN Usage
Contributed by Ray Buland and updated by Rob Casey
The SEED format was created by seismologists, primarily interested in teleseismically recorded earthquakes, for the
purpose of facilitating the exchange of digitally recorded ground motion. The development and subsequent evolutionof SEED had been performed under the auspices of the Federation of Digital Seismographic Networks (FDSN). Thisdevelopment was based on extensive practical experience in digital waveform data exchange. However, the subsequentevolution has been heavily influenced by numerous real-world problems in the implementation of FDSN data collectionand exchange, some that were anticipated at the outset and some that were encountered later. Despite this orientation,
the original SEED designers had the foresight to make SEED very general. In fact, SEED should already encompass(or be easily extended to encompass) any type of equally sampled time series data recorded at discrete points on thesurface of a planet. For example, SEED is already being used to exchange temperature, barometric pressure, and windspeed data as part of the state-of -health information recorded at a seismic station. The format is also currently being
used to exchange tilt, strain, creep, magnetic field, or other geophysically interesting time series.
While experience indicates that the generality and flexibility designed into SEED have and will continue to serve
us well in warding off premature obsolescence, they also have their price. For example, the flexibility of SEED has
contributed significantly to its complexity. The generality of SEED has also created (unexpected) practical problems.
In particular, SEED is so general that access to similar types of information exchanged among the members of auser group (such as the FDSN) cannot be easily automated without additional usage conventions. The most obvious
example is in naming station channels. Without a standard (such as that described in Appendix A) it would be very
difficult (although possible in principle) to formulate and fill requests for similar types of data contributed by various
members of the FDSN to a unified data management center.
To understand this problem, consider a request for broadband, seismometer data. This request would be generally
understood by any FDSN member to refer to data with a sample rate between 10 and 80 samples per second, a sensitive
bandwidth of at least two decades in frequency, and a sensitivity sufficient to record earth noise over a significant
portion of the bandwidth.

Standard for the Exchange of Earthquake Data - Reference Manual • 213

Appendix L
Although all of this information is encoded in the Station Control Headers, it would be very difficult (and time consuming)
to analyze the response information, in particular, to glean the needed information each time a request for data was formulated. The channel naming convention summarizes this information in a human readable mnemonic shorthand that also
works with Relational Database schemas, making the request process natural and straightforward. In essence, by sacrificing some of the generality of SEED, a practical data distribution problem has been solved in such a way as to contribute tomutual understanding among users and to the automation and efficiency of the data request retrieval process.
The FDSN has found it convenient to codify a number of these usage conventions in order to facilitate the flow of data
among FDSN members and scientists using FDSN data. These conventions will be described in the following. Note that
it is very important to distinguish between SEED definitions and FDSN usage conventions. FDSN usage conventions
in no way restrict the generality of the SEED format for groups of users who deal with other types of data or who serve
different communities. However, it is important to understand the concept of such conventions as it is highly probable that
other groups will find it convenient or even necessary to formulate their own usage conventions for reasons similar to the
FDSN’s.
In general, information found in the main body of this Manual describes SEED standards. Information found in the appendices, however, falls into several categories. For example, Appendices C (Specifying and Using Channel Response
Information), D (The Data Description Language), F (Cross Reference for Fields in Abbreviation Dictionaries), H(Effective Times and Update Records), and K (Flinn-Engdahl Seismic Regions) all seek to explain, organize, or codify theusage of various SEED blockettes or fields and should be considered to be integral parts of the SEED specification. On theother hand, Appendix A(Channel Naming) and Appendix J (Network Codes) describe FDSN usage conventions while Appendix B (The Steim
Compression Algorithm) describes a data compression format used primarily by some FDSN members. Appendix E(Sample Logical Volumes) shows an example drawn from one FDSN member.
FDSN usages conventions fall into two classes: 1) common terminology and 2) channel description standards. The
channel naming and network code conventions falls into the first class. Other terminology conventions include standards
for unit naming (particularly non-SI units such as COUNTS) and standards for naming Data Description Language (DDL)
specifications. The former contributes to automation in interpreting instrument response descriptions by end users forchannels from various FDSN member networks. The latter provides a processing short cut as a DDL parser need not be
invoked for the handful of currently extant FDSN binary data formats. In other words, the DDL name is used to select abinary data interpretation routine, by-passing the more cumbersome DDL parser driven interpretation.
Channel description standards fall into two chronically troublesome areas: 1) time keeping and 2) response specification. These seem to be subjects that each seismological network operator has had to think a great deal about and, consequently, about which each operator has formed very definite ideas (and operational procedures). Some of the divergencein usage among FDSN members has resulted in more precise definitions of the SEED standard itself. However, otherissues were resolved by additional usage conventions. For time keeping, it was decided that the basic SEED definitions
were generally adequate with minor extensions. In particular, the clarification that the channel sample rate defined in
the Channel Identifier Blockette [52] and in the Fixed Section of the Data Header (FSDH) should be the nominal sample
rate resulted from this discussion. A new blockette (Data Record Blockette [100] was added for cases where the actual(average) sample rate deviated significantly from the nominal rate in the Blockette [52] and FSDH. Further, the FDSN
usage convention that short term deviations from the actual sample rate must be handled through the time correction fields
in the Fixed Section of the Data Header rather than by frequent changes of the nominal sample rate (through the channel
effective date mechanism) was adopted, so that repeated updates to the headers are not imposed, or required. These
clarifications act to make time keeping more uniform among FDSN members and more comprehensible to end users. The
convention concerning rate changes makes channel related information more manageable.
Usage conventions for response information were adopted both to make access to the data more consistent and convenient
and to establish minimum acceptable standards for completeness. In the former case, the clarification of the SEED
standards that the A0 constant must correctly normalize the relative transfer function at the given reference frequency in
the Response (Poles & Zeros) Blockette [53] coupled with the FDSN convention that a stage 0 Channel Sensitivity/ Gain
Blockette [58] must be given greatly simplifies the usage of response information by the end user. In the latter case, FDSN
usage requires that all digital FIR and IIR filter coefficients be given in addition to the poles and zeros of the Laplace
214 • Standard for the Exchange of Earthquake Data - Reference ManualAppendix Ltransform of the analogue response. This convention is highly specific to the FDSN. It is currently the most complete
and precise method of defining the hybrid analogue/digital transfer function of a seismological instrument. This convention was considered appropriate for the FDSN as FDSN networks are specifically designed to provide data for themost demanding waveform analysis work.

Appendix

In summary, while generality and flexibility of the SEED standard have many benefits, various SEED user groups
will probably find it desirable to superimpose usage conventions that limit the generality of SEED for their specificpurposes. The above discussion presents current FDSN usage conventions as a guide to FDSN members and as an
example of how such conventions might arise for other SEED user communities. As we have seen, usage conventions can have the following benefits: 1) establishing a minimum acceptable level of station/ channel documentation,2) providing mechanisms to facilitate the automation of data requests and retrieval, and 3) providing a consistentframework to facilitate the analysis of the data by the end user.

L

Standard for the Exchange of Earthquake Data - Reference Manual • 215

Appendix L

216 • Standard for the Exchange of Earthquake Data - Reference ManualBibliography

Bibliography

Bibliography

Duncan Carr Agnew, “Conventions for Seismometer Transfer Functions” 1987 Personal Correspondence with C. R.
Hutt of the Albuquerque Seismological Laboratory.
Robert R. Blandford, David Racine, and Raleigh Romine, Single Channel Seismic Event Detection, 1981 VELA
Seismological Center Report VSC-TR-81-8.
James N. Murdock, and Charles R. Hutt, A New Event Detector Designed for the Seismic Research Observatories,
1983 USGS Open File Report 83-785.
James N. Murdock, and Scott E. Halbert, A C Language Implementation of the SRO (Murdock) Detector/Analyzer,
1987 USGS Open File Report 87-158.
Bruce W. Presgrave, Russell E. Needham, and John H. Minsch, Seismograph Station Codes and Coordinates — 1985
Edition, 1985 USGS Open File Report 85-714.
Samuel D. Stearns, Digital Signal Analysis, 1975 Hayden Book Company, New Jersey.
Samuel D. Stearns and Ruth A. David, Signal Processing Algorithms, 1987 Prentice—Hall, New Jersey.

Standard for the Exchange of Earthquake Data - Reference Manual • 217

IndexAabbreviation dictionary 15, 41-62, 110-111
acceleration 124, 152
activity flags 181-182
administrative 124
aliasing 141
analog 1, 53-55, 71-72, 149-150
ASCII 9-17, 27-34, 110-120, 173-186
asterisk 32
author 44
azimuth 67, 68, 110, 124-128

B
Band Code 124
beam 48, 69, 110-111, 125
binary 14-17, 28-34, 97-98, 105-110, 115-122, 162-163
bit 33,-34, 64-65, 99-116, 131-139, 154, 162-167
bit order 163-167
blockette 4-121, 153- 156, 161, 175, 181-187
Bolometer 128
broadband 123, 203
BTIME 33-34, 98-112
BYTE 101-113, 186byte order 113, 186Ccalibration input 67-69, 105-108
carriage return 129
cascades 141
channel 8-15, 20-27, 64-70, 77-79, 93-98, 105-107,		
119-129, 134-137
CHAR 33, 102-108, 112
Cited Source 44, 92, 184
clock 67, 98-99, 112-114, 181-182
comments 43, 64-67, 119, 121
compression 42, 102-103, 131-139, 170-173, 186
Computer readable 9
continuation code 32
continuous 95, 120, 122, 149, 151
Creep Meter 125
cross references 9

Ddata blockettes 97-99
data description language 10, 34, 65, 161
Data Format Dictionary 24, 42, 67-68, 117, 161, 183-184
Dataless SEED Volumes 4, 11
Data Only 4, 113, 185-187
data quality 2, 5, 43, 98-100, 181-182
data record 17-18, 25-33, 68, 94-99, 110-117, 120-122,
133-134, 181-187
Data Transmission 27
DDL 65, 113, 161-162, 167, 172, 185-186

decimation 20-23, 59, 77, 141, 151-155
decoder 42, 65
decoder keys 42
depth 67-68, 126-128
digital 1-2, 8-11, 25, 27, 49-58, 71-83, 99, 102,119-123, 141-155
digitizer 68, 86, 141, 150-152
displacement 124, 127
dip 68, 124-128E
efficient 9-10
Electronic Test Point 125
elevation 68
End-of-file marks (EOF) 12
encoded 137-140
endian 65, 113, 115, 137, 162-167, 181-186
end time 95-96
event 8, 11, 14, 19-27, 35, 38, 44, 89-104, 120-122, 134
exponent 30-33, 68, 113, 169-170, 186

F
FDSN 65, 98, 113, 124, 185-186
Field Volume 24, 35, 36
file 115-116, 139, 182
filter stages 73
Finite Impulse Response (FIR) 20-22, 49-50, 73-74,
82-83, 142-158, 183-184
Fixed Section of Data Header 5, 98, 181
Flinn-Engdahl 5, 92, 195-202
FLOAT 33, 65, 101-112

G
gain 60, 78, 86, 113, 142, 147-156, 162-170
Geophone 127
gravimeter 69, 127Hhumidity 126
hydrophone 125
hypocenter 8, 11, 44, 89, 92, 122I
I/O flags 99
IEEE floating point 33, 113, 186
Infinite Impulse Response (IIR) 56, 71-74, 121, 148, 151
input units 51-58, 71-76, 150-156
Instrument Code 124-128
integer 30-34, 68, 112-113, 131, 138-139, 162-172
integral/integrate 139
IRIS 45, 65, 98, 113, 143, 146, 175-176, 186-187

Llabel 5, 38
latitude 64, 92
least significant bit 162
Linear Strain 127
location code 37, 48
LOG 129, 181
Logical Record 121
Logical Record Size 34, 64-65, 181-186
longitude 64, 9long period 25

M
Magnetometer 126
magnetic tape 12, 121, 131
magnitude 43-44, 92, 150, 158-159
memory 10, 133, 140,
MiniSEED 4, 11, 12
most significant bit 34, 162
multiplexed data 67, 119
Multiplexing 11, 119-121

N
Network Code 5, 37, 64, 93, 95, 98
Null 31Noise records 12
normalization factor 53, 71, 149-153
Nyquist frequency 141-142

O
offset 59, 77, 99-102, 112-115, 129, 152-156, 162-165
Orientation Code 124-128
output units 51-61, 71-76, 84, 150-156
overflow 48, 73

P
period 10, 25, 36, 91, 93, 102-103, 124, 127phase 5, 8, 11, 14, 18, 24, 57, 75, 77, 89, 93, 148-152
Physical and Logical Volumes 14
POD 28
Poles & Zeros 20-24, 46, 53, 63, 71, 73, 80, 183-184
polynomial 4, 51-52, 61-62, 72, 84-87, 148-151
Portable 9
Pressure 69, 85-86, 125, 176
pseudo code 19

R
rainfall 127
RDSEED 28, 187
real-time 7-11, 27
record length 12, 15, 29, 36-38, 67-68, 113, 181-187
response 3-4, 20-24, 37, 41-88, 119-125, 141-151, 176
reversed 68
robust 27

S

sample rate 4, 59, 100-101, 141-142, 150-157, 168

SEED 1-28
Seismometer 124, 176
self defining 27, 120
sensitivity 20-23, 60, 78, 119, 147-156
sensor 4, 51-52, 61-62, 84-88, 123-124, 137, 149
sequence number 32, 39-40, 71-82, 94-98, 120-121, 153-156
signal-to-noise ratio 93
signed integer 131, 165
single end-of-file marks 12
software 2, 8-10, 14, 24, 28, 116
SOH 129
start time 94-99, 112-114
station 1, 4-29, 33-48, 63-70, 89-99, 112, 119-123, 175
station control headers 15-16, 89, 122, 175
Steim1 Compression 131
Steim2 Compression 65, 135-136, 176
sub-sequence number 94-96
symmetry 4, 49-50, 82-83

Ttape 12, 24-25, 36, 121, 131, 134
telemetry 10, 12, 19, 27, 115, 122, 138, 173
temperature 69, 86-88, 126, 203
Tide 127
tilde 30-31, 42
Tilt Meter 124
TIME 31- 40, 60-67, 78-79, 91-95, 181-182
Time correction 98-99
time span 8-11, 15-16, 25-29, 38-40, 89-97, 119-122, 175
time span control header 10, 11, 40, 89
truncated 32
type code 12, 32

U
UBYTE 33, 99, 101-116
ULONG 33, 105-108, 112, 115
ultra long period 125
Units Abbreviation 24, 43, 50-58, 61, 68, 72-76, 83-84
Universal Time Coordination (UTC) 31
unsigned integer 138-139, 164-165, 171
update flag 10, 65
updating 10
USNSN 7, 137-140, 173
UWORD 98-115

Vvariable length 30-34, 38, 116, 120, 137
volume index control headers 15, 175
Volume Time Span 40, 89

Wweather 123-125
wind 128, 176, 203
WORD 33, 98-99
word boundaries 34
word length 162
word order 11, 34, 64-65, 113, 163, 181-186