From: stead@skadi.CSS.GOV (Richard Stead)
Newsgroups: sci.geo.geology
Subject: Re: Seismic Data
Date: 27 Jan 93 00:38:25 GMT

In article <1k4algINNi37@morrow.stanford.edu>, williams@pangea.Stanford.EDU (Tom Williams) writes:
> In article <1993Jan26.165146.10004@news.unige.ch> jordi@scsun.unige.ch writes:
> >In article <C1GvA6.6wq@acsu.buffalo.edu>, v103pye8@ubvmsb.cc.buffalo.edu (BRUCE WAPPMAN) writes:
> >|> I would like to know how seismic data is stored, the format and posible
> >|> conversions, eg. to use on a PC or SUN system. Also are there are any FTP 
> >|> sites to get raw or processed seismic data? I am doing a independent study
> >|> and would like to learn how to interpretate seismic profiles, and would
> >|> like to know if it is possible to obtain it from annonymous FTP. Are there
> >|> any PD or Shareware programs that I could use to process the data and 
> >|> examine by using computers (UNIX or IBM)?  
> >
> >A popular seismic data encoding is SUDS (for Seismic Unified Data System).
> 
>   WHOA.  Y'all are talking about two different kinds of seismic data.
> Most of the discussion here recently about 'seismic' data has to do
> with measurements of earthquakes.
> 
>   jordi@scsun was wondering about access to reflection seismograms
> I believe, since he said 'seismic profiles'.  In answer to his question
> about public access to data, inferring that he means reflection seismograms,
> I'd say that because it costs SO MUCH to acquire, it's generally not
> the type of thing that's given away by public access, it's given
> away by the individual acquiring agency upon specific request if at
> all.  Second, if we're NOT talking about earthquakes, but rather reflection
> seismology, then the data storage requirements in terms of sheer volume
> make it unlikely that any meaningful amount of data would be accessible
> by FTP.  Again, ask those who have it.

However, one of the aims of SUDS was to unify the exploration and
observational seismology data sets.  So mentioning SUDS was appropriate.

Also, it is a fallacy to consider storage requirements of observational
seismology vs. exploration as greatly different.  A couple examples
from the program here - we are in the process of trying to dispose
of something around 100,000 tapes (it's a shame to toss data, even if
it's not so valuable, but there is simply no way to get at all this
or preserve it, so it has to go).  We are in the initial stages of studying
a project that could eventually produce up to 60 Terabytes a day of data
(that's a maximum, hopefully we will be dealing with a lot less).  This
is purely observational seismology - specifically nuclear test ban monitoring.

Back to the original question -

The main problem with your request is that the data are massive, no matter
how you look at it.  That is why none are publicly available - even if
an agency had no problem with letting people have the data, the communications
overhead is prohibitive.

As far as formats, there are as many as the day is long.  Our parameter
data at CSS is in an Oracle database - the schema consists of 21 standard
tables and about 40 auxiliary tables.  The raw data are on line on
magnetic or optical storage, and off line on tape.  There are many other
formats used in observational seismology - common ones are SAC, AH, CUSP
and SEED.  In exploration seismology, SEGY has pretty much taken over, as
far as I'm aware, but I rarely work with such data.  These are just the
common formats used as much to permit data exchange as any other region.
There are 100s, maybe 1000s of formats used for special purposes.

Having said all that, there is a project - the Joint Education Initiative -
that is getting real data into classrooms.  They have a CD for PCs and Macs
that I understand includes some seismic data among many other data sets.
If you just want any real data in an accessible form, this may be a good
way to go.  They have a list service at JEI-L@UMDD.umd.edu (subscribe
by sending mail to listserv@umdd.umd.edu with body "subscribe JEI-L <your name>"


--
Richard Stead
Center for Seismic Studies
Arlington, VA
stead@seismo.css.gov
Newsgroups: sci.geo.geology