DOI: 10.5061/dryad.0000000d4
title: Data from: Catalog of non-seismic short duration events offshore cascadia

description: Ocean-bottom seismometers (OBS) often record non-earthquake signals termed
 short-duration events (SDEs) that are typically recorded on one station
 with durations of ~1 s and frequencies between 4-30 Hz. Their origin has
 been attributed to animals bumping the sensor and a variety of physical
 mechanisms, including the passage of methane bubbles through sediments and
 across the seafloor.  We analyzed records from a subset of OBSs
 deployed on the Cascadia margin and Juan de Fuca plate as part of the
 Cascadia Initiative experiment and cabled OBSs from the Ocean
 Observatories Initiative Regional Cabled Array for the occurrence and
 characteristics of SDEs.  SDEs are observed on all OBSs at rates
 that vary by over two orders of magnitude.  This data set
 comprises a catalog of short duration from the OBS analyzed along with the
 Python code used to analyse the data, a list of stations and the time
 intervals analyzed, and ocean tide height predictions at each site.
description: The data set was collected with ocean bottom seismometers
 deployed as part of the Cascadia Initiative Experiment (Toomey et al.,
 2014)and as part of the Ocean Observatories Initiative Regional Cabled
 Array (Smith et al.).  Short duration events (SDEs) were detected by first
 filtering the seismic records with a 5-12 Hz bandpass filter and then
 using a recursive short term/long term RMS amplitude detector with a
 short- and long-term durations of 0.25 s and 30 s, respectively, and a
 trigger ratio of 4 (Withers et al., 1998).  Various parameters were then
 determined for each short duration event (SDE) as described in the README
 file accompanying this data set Smith, L. M., Barth, J.
 A., Kelley, D. S., Plueddemann, A., Rodero, I., Ulses, G. A., ...
 & Weller, R. (2018). The ocean observatories initiative.
 <em>Oceanography</em>, <em>31</em>(1),
 16-35. Toomey, D. R., Allen, R. M., Barclay, A. H.,
 Bell, S. W., Bromirski, P. D., Carlson, R. L., ... & Wilcock, W.
 S. (2014). The Cascadia Initiative: A sea change in seismological studies
 of subduction zones. <em>Oceanography</em>,
 <em>27</em>(2), 138-150. Withers, M.,
 Aster, R., Young, C., Beiriger, J., Harris, M., Moore, S., &
 Trujillo, J. (1998). A comparison of select trigger algorithms for
 automated global seismic phase and event detection. <em>Bulletin of
 the Seismological Society of America</em>,
 <em>88</em>(1), 95-106.
description: # Data from: Catalog of non-seismic short duration events offshore
 cascadia This repository contains information related to the manuscript
 "Non-Seismic Short Duration Events Offshore Cascadia: Characteristics
 and Potential Origin" by Leo M. F. MacLeod and William S.D. Wilcock,
 in review at the journal “Seismological Research Letters”. # Summary of
 Files **README.md** – Description of repository contents (this file)
 **CascadiaShortDurationEvents.zip** - A zip file containing the following
 directories and files: **Catalogue_SDE.py** – Python code used for
 generating the station event catalogues used in this study.
 **ListofStations.csv** – Comma separated variable file with details on
 each station. **TideHeightData** – Directory containing data files of
 tidal height for each station used. **DataCatalogue** – Directory
 containing comma separated variable files for each station with data for
 each short duration event detected. # File Details \**Catalogue_SDE.py **
 A Python code used to generate the data used in the analysis of this study
 that can be found in the “DataCatalogue” directory. This code detects
 short duration events for a given ocean bottom seismometer station and
 range of times. Data is pulled from the Incorporated Research Institutions
 for Seismology (IRIS) Data Management Center (now the Earthscope
 Consortium Seismological Facility for the Advancement of Geoscience (SAGE)
 Data Services). Parameters for the station identifier and time range can
 be changed. Code runs in intervals of one hour and the start times can be
 modified to restart from a specific time if a crash occurs. Data is saved
 for each station catalogue as a comma separated variable (csv) file. This
 Python code uses data from ListofStations.csv with data on each station
 used and the directory “TideHeightData” containing files on tidal height
 by station. \**ListofStations.csv ** A comma separated variable file with
 information about the stations that is needed to run the Python code
 Catalogue_SDE.py. It has eight columns of data: Column 1 is the station
 name. Column 2 is the network code for the station. This is either “7D”
 for Cascadia Initiative Community Experiment or “OO” for Ocean
 Observatories Initiative Regional Cabled Array. Column 3 is the station
 depth in meters. Column 4 is the station latitude in decimal degrees
 north. Column 5 is the station longitude in decimal degrees east. Column 6
 is the start time of the station in Unix epoch. Column 7 is the end time
 of the station in Unix epoch. Column 8 is the amplitude that an event must
 reach to be counted as a short duration event as opposed to background
 noise. **TideHeightData** A directory that contains one data file for each
 station analyzed with the station name as the first 4 or 5 characters
 before the underscore. These files are used to add the tidal height in
 column 13 for each csv file in the “DataCatalogue” directory. Each file
 contains two columns: Column 1 is the time in Unix epoch. Column 2 is the
 tidal height in meters obtained from the Oregon State University TPXO
 tidal model as implemented in SPOTL (Agnew, D. C. (2013) Some Programs for
 Ocean-Tide Loading, Program Versions 3.3.0.2, Scripps Institution of
 Oceanography, Technical Report,
 [https://igppweb.ucsd.edu/~agnew/Spotl/spotlman.pdf](https://igppweb.ucsd.edu/~agnew/Spotl/spotlman.pdf)). **DataCatalogue** A directory that contains one csv file for each station analyzed with the station name as the first 4 or 5 characters before the underscore. Each row in the file contains data for one detected short duration event. Details on the math for calculating the characteristics of each event are included in the Materials and Methods section of the manuscript. Each file contains 13 columns: Column 1 is the station name. Column 2 is the start time of the detected event in Unix epoch. Column 3 is the end time of the detected event in Unix epoch. Column 4 is the total duration of the event in seconds. Column 5 is the number of peaks counted in the event. Column 6 is the maximum amplitude digital units of the downloaded data after filtering with a 5-12 Hz Butterworth bandpass filter. Column 7 is greatest change in amplitudes between peaks in multi-peak events in digital units of the downloaded data after filtering with a 5-12 Hz Butterworth bandpass filter. A value of 0 means there was only one peak so a distance between peaks is inapplicable. Column 8 is the mean energy weighted time of the event (equation 2 in the manuscript). Column 9 is the energy weighted duration of the event in seconds (equation 1 in the manuscript). Column 10 is the average frequency of the event in Hz (equation 3 in the manuscript). Column 11 is the bandwidth of the event in Hz (equation 4 in the manuscript). Column 12 is the elevation angle of the sun in degrees above the horizon. Column 13 is the tide height during the event in meters.