Multichannel seismic-reflection and navigation data collected using SIG ELC1200 and Applied Acoustics Delta sparkers and Geometrics GeoEel digital streamers during USGS field activity 2020-014-FA, Southwest of Puerto Rico, March 2020

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Frequently anticipated questions:

What does this data set describe?

Title:
Multichannel seismic-reflection and navigation data collected using SIG ELC1200 and Applied Acoustics Delta sparkers and Geometrics GeoEel digital streamers during USGS field activity 2020-014-FA, Southwest of Puerto Rico, March 2020
Abstract:
In March 2020, the U.S. Geological Survey and the University of Puerto Rico Mayagüez (UPRM) Department of Marine Sciences conducted a marine seismic-reflection experiment focused on observing geophysical evidence of submarine faulting and mass wasting related to the southwestern Puerto Rico seismic sequence of 2019–20. The seismic sequence culminated with a magnitude 6.4 earthquake centered beneath Guayanilla Canyon on January 7, 2020 and caused shoreline subsidence, rockfalls, and considerable damage to buildings. The survey was conducted during March 7–13 out of the UPRM Isla Magueyes Laboratories aboard the research vessel Sultana. Approximately 226 line kilometers of multichannel seismic reflection data were collected across the insular shelf and upper slope of the Caribbean Sea between La Parguera and Guayanilla Bay and offshore in the vicinity of Guayanilla Canyon. The seismic profiles image up to 0.5 seconds (approximately 0.5 kilometers) of the sedimentary section beneath the sea floor and provide evidence of faults and mass wasting.
Supplemental_Information:
Support for 2020-014-FA was provided by the USGS Coastal and Marine Geology Program. Additional information on the field activity is available from https://cmgds.marine.usgs.gov/fan_info.php?fan=2020-014-FA
  1. How might this data set be cited?
    Baldwin, Wayne E., Chaytor, Jason D., Foster, David S., Moore, Eric M., Nichols, Alex R., and Uri S. ten Brink, 20210713, Multichannel seismic-reflection and navigation data collected using SIG ELC1200 and Applied Acoustics Delta sparkers and Geometrics GeoEel digital streamers during USGS field activity 2020-014-FA, Southwest of Puerto Rico, March 2020: data release DOI:10.5066/P96GY6TQ, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Baldwin, W.E., Chaytor, J.D., Foster, D.S., Moore, E.M., Nichols, A.R., and ten Brink, U.S., 2021, Multichannel seismic-reflection and navigation data collected using SIG ELC1200 and Applied Acoustics Delta sparkers and Geometrics GeoEel digital streamers during USGS field activity 2020-014-FA, Southwest of Puerto Rico, March 2020: U.S. Geological Survey data release, https://doi.org/10.5066/P96GY6TQ
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -67.036516
    East_Bounding_Coordinate: -66.581641
    North_Bounding_Coordinate: 17.994033
    South_Bounding_Coordinate: 17.778188
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/60a2d193d34ea221ce432fe5/?name=2020-014-FA_MCSBrowseImage.jpg (JPEG)
    2020-014-FA MSC data release collage.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 07-Mar-2020
    Ending_Date: 13-Mar-2020
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Shapefile, CSV, PNG Image, SEG-Y
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is WGS 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257224.
  7. How does the data set describe geographic features?
    2020-014-FA_MCS_cmpTracklines.shp
    MCS CMP Trackline shapefile for survey 2020-014-FA (19 polyline features). (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Coordinates defining the features.
    LineName
    Name of the trackline along which seismic-reflection data were collected in the format: FieldActivity#-FileNumber (i.e.'2020-014-FA_Line0003'). (Source: U.S. Geological Survey) Character set
    ImageName
    PNG image name of seismic-reflection profile corresponding to survey line. (Source: U.S. Geological Survey) Character set
    CMP_init
    Common midpoint number at the start of the survey line. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:1
    Units:CMP
    Resolution:1
    CMP_end
    Common midpoint number at the end of the survey line. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1387
    Maximum:17287
    Units:CMP
    Resolution:1
    Year
    Calendar year the data were collected (Source: U.S. Geological Survey) Character set
    SurveyID
    WHCMSC field activity number (e.g. "2020-014-FA" where 2020 is the survey year, 014 is survey number of that year, and FA is Field Activity). (Source: U.S. Geological Survey) Character set
    VehicleID
    Survey vessel name. (Source: U.S. Geological Survey) Character set
    DeviceID
    Device used to collect seismic-reflection data (either SIG ELC1200 Mini Sparker or Applied Acoustics Delta Sparker). (Source: U.S. Geological Survey) Character set
    Length_km
    Length of seismic-reflection data line in kilometers (UTM Zone 19N, WGS 84) calculated in the SQLite database. (Source: U.S. Geological Survey)
    Range of values
    Minimum:3.17
    Maximum:27.10
    Units:kilometers
    Resolution:0.01
    2020-014-FA_MCS_cmp500.shp
    MCS 500-interval CMP point shapefile for survey 2020-014-FA (254 point features). (Source: U.S. Geological Survey)
    FID
    Internal feature number. (Source: Esri) Sequential unique whole numbers that are automatically generated.
    Shape
    Feature geometry. (Source: Esri) Coordinates defining the features.
    East
    Easting coordinate in UTM Zone 19 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:707952.70
    Maximum:756293.52
    Units:meters
    Resolution:.01
    North
    Northing coordinate in UTM Zone 19 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:1967140.65
    Maximum:1990932.52
    Units:meters
    Resolution:.01
    Lon
    Longitude coordinate in decimal degrees, WGS 84 (negative indicates west longitude) (Source: U.S. Geological Survey)
    Range of values
    Minimum:-67.03645
    Maximum:-66.5816428
    Units:degrees
    Resolution:1E-06
    Lat
    Latitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:17.778188
    Maximum:17.993971
    Units:degrees
    Resolution:1E-06
    LineName
    Name of the trackline along which seismic-reflection data were collected in the format: FieldActivity#-FileNumber (i.e.'2020-014-FA-Line0003'). (Source: U.S. Geological Survey) Character set
    ImageName
    PNG image name of seismic-reflection profile corresponding to survey line. (Source: U.S. Geological Survey) Character set
    CMP
    Common midpoint number. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:17287
    Units:CMP
    Resolution:1
    Year
    Year the data were collected YYYY. (Source: U.S. Geological Survey) Character set
    SurveyID
    WHCMSC field activity identifier (e.g. "2020-014-FA" where 2020 is the survey year, 014 is survey number of that year, and FA is Field Activity). (Source: U.S. Geological Survey) Character set
    VehicleID
    Survey vessel name. (Source: U.S. Geological Survey) Character set
    DeviceID
    Device used to collect seismic-reflection data (either SIG ELC1200 Mini Sparker or Applied Acoustics Delta Sparker). (Source: U.S. Geological Survey) Character set
    2020-014-FA_MCS_cmpnav.csv
    MCS CMP comma separated values file for survey 2020-014-FA (112415 point features). (Source: U.S. Geological Survey)
    East
    Easting coordinate in UTM Zone 19 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:707952.70
    Maximum:756293.52
    Units:meters
    Resolution:.01
    North
    Northing coordinate in UTM Zone 19 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:1967140.65
    Maximum:1990932.52
    Units:meters
    Resolution:.01
    Lon
    Longitude coordinate in decimal degrees, WGS 84 (negative indicates west longitude) (Source: U.S. Geological Survey)
    Range of values
    Minimum:-67.03645
    Maximum:-66.581641
    Units:degrees
    Resolution:1E-06
    Lat
    Latitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:17.778188
    Maximum:17.993971
    Units:degrees
    Resolution:1E-06
    LineName
    Name of the trackline along which seismic-reflection data were collected in the format: FieldActivity#-FileNumber (i.e.'2020-014-FA_Line0003'). (Source: U.S. Geological Survey) Character set
    ImageName
    PNG image name of seismic-reflection profile corresponding to survey line. (Source: U.S. Geological Survey) Character set
    CMP
    Common midpoint number. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:17287
    Units:CMP
    Resolution:1
    Year
    Year the data were collected YYYY. (Source: U.S. Geological Survey) Character set
    SurveyID
    WHCMSC field activity identifier (e.g. "2020-014-FA" where 2020 is the survey year, 014 is survey number of that year, and FA is Field Activity). (Source: U.S. Geological Survey) Character set
    VehicleID
    Survey vessel name. (Source: U.S. Geological Survey) Character set
    DeviceID
    Device used to collect seismic-reflection data (either SIG ELC1200 Mini Sparker or Applied Acoustics Delta Sparker). (Source: U.S. Geological Survey) Character set
    2020-014-FA_MCS_shtnav.csv
    MCS shot point comma separated values file for survey 2020-014-FA (48761 point features). (Source: U.S. Geological Survey)
    East
    Easting coordinate in UTM Zone 19 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:707945.7
    Maximum:756293.52
    Units:meters
    Resolution:.01
    North
    Northing coordinate in UTM Zone 19 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:1967151.42
    Maximum:1990939.43
    Units:meters
    Resolution:.01
    Lon
    Longitude coordinate in decimal degrees, WGS 84 (negative indicates west longitude) (Source: U.S. Geological Survey)
    Range of values
    Minimum:-67.036516
    Maximum:-66.581641
    Units:degrees
    Resolution:1E-06
    Lat
    Latitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:17.778288
    Maximum:17.994033
    Units:degrees
    Resolution:1E-06
    LineName
    Name of the trackline along which seismic-reflection data were collected in the format: FieldActivity#-FileNumber (i.e.'2020-014-FA_Line0003'). (Source: U.S. Geological Survey) Character set
    FFID
    Field File Identification Number of MCS shot gather. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:8616
    Units:shot
    Resolution:1
    Year
    Year the data were collected YYYY. (Source: U.S. Geological Survey) Character set
    JD_UTC
    Julian day and UTC time for of the navigation fix in the format: DDD:HH:MM:SS; Julian day is the integer number (although recorded here in text string format) representing the interval of time in days since January 1 of the year of collection. (Source: U.S. Geological Survey) Character set
    SurveyID
    WHCMSC field activity identifier (e.g. "2020-014-FA" where 2020 is the survey year, 014 is survey number of that year, and FA is Field Activity). (Source: U.S. Geological Survey) Character set
    VehicleID
    Survey vessel name. (Source: U.S. Geological Survey) Character set
    DeviceID
    Device used to collect seismic-reflection data. (Source: U.S. Geological Survey) Character set
    2020-014-FA_MCS_Images
    Portable network graphic images of MCS profiles processed through post-stack migration for survey 2020-014-FA (19 PNG images). (Source: U.S. Geological Survey)
    2020-014-FA_MCS_Segy
    Binary SEG-Y format files of MCS profiles processed through post-stack migration for survey 2020-014-FA (19 SEG-Y files). (Source: U.S. Geological Survey)
    Entity_and_Attribute_Overview:
    The PNG seismic reflection images can be hyperlinked to their corresponding trackline or CMP locations in ArcGIS using the shapefiles '2020-014-FA_MCS_cmpTracklines.shp' or '2020-014-FA_MCS_cmp500.shp', respectively. The images illustrate distance along the profile on the x-axis (annotation at 500 CMP intervals) and two-way travel time (seconds) on the y-axis. The first, last, and multiple of 500 CMP features in '2020-014-FA_MCS_cmp500.shp' correspond to the x-axis tick marks.
    A binary SEG-Y file (Norris and Faichney, 2002) is provided for each survey line containing CMP traces processed through post-stack migration, spiking deconvolution, and time varying gain. A SEG-Y file consists of 1) a 3200-byte textural file header containing general information (see examples following processing steps); 2) a 400-byte binary record with information such as sample rate and record length specific to the data set; and 3) multiple records, one seismic reflection trace per record. Each trace record is preceded by a 240-byte "trace header" containing information such as trace number and acquisition day and time specific to each trace. The trace data are represented as a time series of unitless 16-bit integer or 32-bit real numbers proportional to the pressure recorded at each hydrophone. The SEG-Y file is useful only if you have access to specialized software designed to process and display seismic reflection data.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Wayne E. Baldwin
    • Jason D. Chaytor
    • David S. Foster
    • Eric M. Moore
    • Alex R. Nichols
    • Uri S. ten Brink
  2. Who also contributed to the data set?
    The University of Puerto Rico Mayagüez - Department of Marine Sciences Isla Magueyes Laboratories staff and director Ernesto Otero provided critical facilities and logistical support during this field activity. The expert seamanship and knowledge of local waters provided by Captain Orlando Espinoza and the crew of the R/V Sultana were instrumental in the success of the program.
  3. To whom should users address questions about the data?
    Wayne E. Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    US

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov

Why was the data set created?

This dataset contains source shot, common mid-point (CMP) and trackline navigation, profile images, and stacked SEG-Y trace data for approximately 227 km of multichannel seismic-reflection data collected by the U.S. Geological Survey during USGS field activity 2020-014-FA offshore of southwest Puerto Rico. Images of each seismic profile were generated in order to provide portable and easily viewable alternatives to the SEG-Y versions of the data. Each profile image can be hyperlinked to its corresponding trackline navigation contained within the Esri polyline shapefile '2020-014-FA_MCS_cmpTracklines.shp'. CMP and tick marks along the top of the PNG images correlate to the positions of 500 CMP intervals within the Esri point shapefile '2020-014-FA_MCS_cmp500.shp'. This information allows for spatial correlation of MCS seismic-reflection profiles images with other geophysical and sample data for investigating sea-floor morphology and stratigraphy in the area.

How was the data set created?

  1. From what previous works were the data drawn?
    MCS data (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, Raw MCS data.

    Type_of_Source_Media: disc
    Source_Contribution:
    Multichannel seismic-reflection data were shot using multi-electrode sparker arrays (SIG ELC1200 in water depths < 100 m and Applied Acoustics Delta in water depths > 100 m) powered by an Applied Acoustics CPS-D power supply that was set to output between 200 and 2400 Joules. The sparker sources were towed from the port quarter of the R/V Sultana, between 31.13 and 38.93 meters astern of the NRP. The sources were triggered on time using the Geometric CNT-1 software at intervals between 1 and 5 seconds (depending on water depth and record length), producing along track shot spacings between approximately 2 and 10 meters. Shots were recorded using a Geometrics GeoEel digital streamer connected to a Geometrics Streamer Power Supply Unit (SPSU). Four 12.5 m solid state sections (1.5625 m group spacing) composed an active section of 50 m and 32 channels (See processing step 1.3 for a table of streamer geometry by line). The GeoEel streamer was towed from a boom on the starboard quarter. The center of the first (channel 1) and last (channel 32) active groups trailed the NRP approximately 52.53 m and 101.9 m respectively. A 10 m isolation section was positioned before the active sections to reduce the impacts of ship tug. Four RBRsolo D depth loggers were spaced along steamer to record streamer depth data. Geometrics CNT-1 seismic acquisition software (version 5.361) running on a Windows PC was used to control the multichannel system, digitally log traces in the Geometrics SEG-D format, and record shot NRP GPS navigation coordinates to the SEG-D external headers. Raw records were recorded over trace lengths between 0.5 and 4 seconds, with sample intervals of 0.25 milliseconds.
  2. How were the data generated, processed, and modified?
    Date: 2020 (process 1 of 4)
    PROCESS STEP 1:
    Shearwater Reveal (version 4.1) and Kingdom Suite (version 2017) seismic processing software was used to execute the following processing flows to produce SEG-Y files of profiles processed through post-stack time migration and deconvolution.
    1. Import SEG-D sequences: SegDRead read raw Geometrics SEG-D shot sequence files, extracted navigation fixes from the external headers, and wrote them to new header words, and converted the source lat/lon positions from seconds of arc to decimal degrees (NRP_LAT, NRP_LON). UTMLatLong projected the geographic navigation to UTM Zone 19N WGS 84 meters (NRP_X, and NRP_Y). Output wrote the trace sequence to Reveal formatted ".seis" files.
    2. Layback geometry assignment, delay removal, and trace edits: Input read sequence files sorted by FFID/CHANNEL. The Python module ShotlineLayback (developed by Nathan Miller of USGS-WHCMSC) defined the source and streamer geometry based on measured horizontal offsets from the navigation reference point (NRP) to the center of the sources (cos) and the centers of the first and last 1.5625 m spaced channel groups. The following lists the linear offsets from the NRP to center of source (COS) and index channels (IC) used to define layback geometry.
    NRP to COS, NRP to IC offset(IC#) -31.13, -52.53(1)/-101.9(32) - Line0003 - Line0004a and Line0008c -38.93, -52.53(1)/-101.9(32) - Line0005 - Line0007a, Line0011 - Line0013b, and Line0015b - Line0017m -36.13, -52.53(1)/-101.9(32) - Line0009, Line0010, and Line0014
    The module interpolated a sail line from the shot NRP positions (NRP_X and NRP_Y), then computed layback positions for the source and channel groups (values were interpolated for all channels in between the defined index channels) for each FFID by translating them back along the sail line by their respective offsets. Layback midpoint positions along the sail line were also computed for each shot/receiver pair. HeaderMath computed and populated a new header word for trace offset using OFFSET = ABS(NRP2CHAN) - ABS(NRP2COS). CMP bin spacing was set to either 0.78125 m (for shallow water lines; Line003, Line004, Line 004a, Line 8c, Line 9, and Line 10) or 3.125 m, the first cmp to 1, and CMP coordinates (BIN_X and BIN_Y) were computed. DBWrite wrote the layback geometry source positions (in UTM 19N WGS84 meters), FFID number, year, day number, and UTC times for the shots in each line to ASCII CSV files.
    ApplyStatic shifted traces (except for Line0005, Line0008c, Line0009, Line0010, and Line0014) by -50 milliseconds to account for the recording delay used during acquisition and adjusted the trace start and end times accordingly. TracesEdits removed channels 7, 15, and 31 from output gathers due to high noise levels.
    4. Apply static corrections:
    For deep water lines (all except Line003, Line004, Line0004a, Line0008c, Line0009, and Line0010): Readings from RBRSolo-D pressure depth recorders spaced along the streamer were inserted into the trace headers for all lines. Input read the geometry corrected trace files. Text files prepared to contain UTC time, offset location of the pressure depth probe along the streamer, and pressure depth values in meters were used as inputs for DBMerge, which matched times and trace offsets in the trace headers with those in the input text files (through interpolation) and populated a new receiver depth header word with pressure depth values for each channel of the active section. HeaderMath also populated a new header word containing an estimated source depth of 1 m, then converted the sum of both static values from meters to milliseconds (dividing by an assumed water column sound speed velocity of 1.5 m/ms) and wrote it to a new header word. The source/receiver static value was then applied to the traces. Static corrections using the depth loggers successfully compensates for vertical movement of the streamer. Output wrote the static corrected traces to new files.
    For shallow water lines (Line0003, Line0004, Line0004a, Line0008c, Line0009, and Line0010): Applying pressure depth static corrections to the shallow water did not produce satisfactory results, most likely due to horizontal movement of the streamer. Consequently, an alternate method to flatten both horizontal and vertical movement was applied. A Reveal flow used Output to write single channel SEG-Y format files for channels 1 to 32 for each line. The single channel (common offset) SEG-Y files were imported into Kingdom Suite (version 2017). The 2D-Hunt auto picker was used to digitize the seafloor reflection and direct arrival on all lines for traces where the two events did not interfere with one another. This resulted in pick on channels 1-16 for all lines except for Line0003 and Line0008c, in which picks were made for channels 1-12 and 1-8, respectively. Except for Line0004 and Line0009, a seven-trace moving average filter was applied to all seafloor horizon picks. An ASCII CSV file of the unfiltered seafloor, filtered seafloor, and direct arrival horizons was exported for each line and channel in which the horizons were digitized containing LineName (including channel number eg."_1"), FFID, and horizon two-way travel time values. All files were edited in the VI editor to eliminate any text other than the channel name from the LineName, and the LineName header was renamed to channel. Direct arrival CSV files were imported into Excel (version 16.48) where one-way direct arrival travel times, average one-way travel direct arrival times, and the difference between the digitized and average one-way direct arrival travel times (as a new field) were calculated for each line-channel. In Reveal, Input read the geometry corrected trace files. The CSV text files containing the unfiltered and filtered seafloor horizons were used as inputs for two DBMerge modules, which matched FFIDs and trace offsets in the trace headers with those in the input text files and populated new unfiltered and filtered seafloor header values. HeaderMath populated an additional header word with the calculated difference between the filtered and unfiltered seafloor horizons ((unfiltered seafloor - filtered seafloor) * -1), and ApplyStatic shifted traces by the resulting values. For all lines (Line003, Line004, Line0004a, Line0008c, Line0009, and Line0010) the CSV text files containing the difference between digitized and average one-way direct arrival travel times were used as inputs to an additional DBMerge module, which matched FFIDs and trace offsets in the trace headers with those in the input text files and populated a new difference direct arrival time header value, HeaderMath converted the difference direct arrival time back to two-way travel time, and ApplyStatic shifted traces by the resulting values. Output wrote the static corrected traces to new files.
    5. Trace preprocessing and noise reduction: Import read files with geometry and static corrections. For Line0004, Line0004a, and Line0009, Despike estimated local median RMS amplitudes within 10 ms windows (specifying 11 traces per window, 25% trace and time window overlap, nearest neighbor interpolation, and replacement scalar of 2), then used the median RMS amplitudes to replace samples that exceeded them by 5 times. The remaining processes were applied to all lines. FXDecon was applied (specifying 5 points, 11 traces per window, 100 ms window length, minimum frequency of 30 or 200 Hz for Delta and SIG sources, respectively, maximum frequency of 1000 or 1400 Hz for Delta and SIG sources, respectively, and 1 percent prewhitening) to attenuate random noise most likely resulting from rough sea states during acquisition. A polygonal FKFilter designed in shot gather f-k spectra for each line was used to rejected noise energy outside of the primary reflections. Trace were Bandpass filtered (300-400-1300-1400 Hz for SIG ELC1200 lines or 70–90–900–1000 Hz for Applied Acoustics Delta lines) and Output wrote preprocessed, noise-reduced traces to new files.
    6. Constant velocity stack, sea floor picking, and 1D velocity model creation: To produce a quality control stack, Input read the preprocessed, noise-reduced, and bandpass filtered traces. NormalMoveout converted traces to zero offset assuming a constant 1500 m/s sound speed through water, Stack produced a single trace per CMP bin, and Output wrote the stacked traces to new files. Sea floor reflection times were digitized for each line and saved to new horizon tables. 1D velocity models were created for each line using VelocityLayer (a python module developed for Reveal by Nathan Miller, USGS), to set RMS stacking velocities of 1500 and 2000 m/s above and below the digitized seafloor horizon, respectively. Trace2Table wrote the 1D velocity models to new database tables.
    7. 1D velocity model stack and post-stack deconvolution: Input read the preprocessed, noise-reduced, and bandpass filtered traces, NormalMoveout converted traces to zero offset using the 1D velocity model table, Stack produced a single trace per CMP bin, and Output wrote the 1D velocity model stacked traces to new files.
    8. Phase shift post-stack migration and migrated stack seafloor picking: Input read the 1D velocity model stacked traces, PostStackMigration performed a phase-shift time migration using the 1D velocity model (specifying maximum frequencies of 1000 or 1400 Hz for Delta and SIG sources, respectively, and the same bin spacing as the input (0.78125 or 3.125 m), and Output wrote the migrated stacked traces to new files. Subsequent to migration, the predicted sea floor picks were overlaid on the migrated trace display, manually adjusted to more closely approximate the migrated sea floor, and saved to new files.
    9. Post-stack deconvolution, time-dependent gain, and top mute: Input wrote read the migrated stacked traces, Deconvolution applied a spiking deconvolution filter (designed using a 2 ms gap length, 50 ms operator length, and 0.2 percent prewhitening factor), Table2Header wrote the migration adjusted sea floor picks to a water bottom time header word, TraceMath applied a time dependent gain function to the traces relative to the migration adjusted digitized seafloor horizon (ifelse(TIME > WBTIME1 - 300, sample * pow((TIME-(WBTIME1-300))/1000,1), 0)), Mute applied a top mute above the migration adjusted digitized seafloor horizon, and output wrote the traces to new files.
    10. SEG-Y output: Input read the migrated stacked deconvolved files. UTMLatLong projected the CMP bin positions from UTM 19N WGS84 meters to geographic and wrote them to new header words. HeaderMath converted the geographic coordinates from decimal degrees to seconds of arc multiplied by a scaler of 100, and set the coordinate unit header to 2 accordingly. DBWrite wrote the CMP positions (in UTM 18N WGS84 meters), CMP number, and year header words to ASCII CSV text files by line. Output wrote the stacked migrated deconvolved traces to SEG-Y Rev. 1 format (32-Bit IEEE floating point). Each output SEG-Y file contains a textural file header similar to the example from Line0003 included below.
    Example migrated stacked file SEG-Y Textural File Header:
    C 1 U.S. GEOLOGICAL SURVEY COASTAL AND MARINE HAZARDS AND RESOURCES PROGRAM C 2 SURVEY_ID: 2020-014-FA AREA: ATLANTIC OCEAN, CARIBBEAN SEA, PUERTO RICO, C 3 VESSEL: R/V SULTANA, YEAR: 2020 LINENAME: LINE0003 C 4 C 5 ACQUISITION: SIG MINI SPARKER, 50 M, 32 CHANNEL GEOEEL C 6 HYDROPHONE STREAMER (1.5625 M GROUPS), 0.25 MS RECORDING SAMPLE INTERVAL, C 7 0.5 SEC RECORD LENGTH, RECORDED IN SEG-D FORMAT. C 8 C 9 C10 PROCESSING: IMPORT SEG-D SEQUENCE FILES, EXTRACT NAVIGATION FIXES FROM C11 EXTERNAL HEADERS, MERGE SEQUENCE FILES TO SEIS FORMAT FILE, DEFINE C12 GEOMETRY WITH CMP BINS (SPACED 0.78125-M) USING NRP NAVIGATION AND C13 LAYBACK OFFSETS, REMOVE DELAY AND SET TRACE LENGTH, REMOVE C14 CHANNELS 7 AND 13-32, APPLY FREQUENCY DOMAIN BANDPASS FILTER C15 300-400-1300-1400 (Hz) APPLY SRC/REC STATIC CORRECTIONS FROM SWELL FILTER C16 AND FLATTEN TO DIFFERENCE BETWEEN DIRECT ARRIVAL AND MEAN DIRECT ARRIVAL C17 FOR THE LINE, APPLY NOISE FILTERS DESPIKE, FX DECON, AND FK FILTER, NORMAL C18 MOVEOUT WITH VELOCITIES 1500 M/S (WATER) AND 2000 M/S (SEDIMENT), STACK, C19 PHASE SHIFT TIME MIGRATION 1D VELOCITY MODEL, SPIKING DECONVOLUTION, C20 TIME DEPENDENT GAIN RELATIVE TO WATER BOTTOM. C21 C22 OUTPUT: 32-BIT IEEE FLOATING POINT SEG-Y C23 RECORD LENGTH: 0.5 SEC C24 C25 CDP COORDINATES ARE STORED IN GEOGRAPHIC ARCSECONDS (SCALED BY 100) C26 DIVIDE BY 360000 FOR DECIMAL DEGREES. C27 COORDINATE SCALAR IN BYTES 71-72 C28 C29 CDP-X AND CDP-Y IN BYTES 181-184 AND 185-188 C30 CDP NUMBER STORED IN BYTES 21-24 C31 C32 C33 FOR ADDITIONAL INFORMATION CONCERNING THIS DATASET, CONTACT: C34 WAYNE BALDWIN (508) 548-8700 x-2226 WBALDWIN@USGS.GOV C35 U. S. GEOLOGICAL SURVEY C36 384 WOODS HOLE RD., WOODS HOLE, MASSACHUSETTS 02543 C37 C38 C39 C40
    Post-cruise processing was conducted by David Foster and Wayne Baldwin. Person who carried out this activity:
    U.S. Geological Survey
    Attn: David S. Foster
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@usgs.gov
    Date: Jul-2021 (process 2 of 4)
    PROCESS STEP 2:
    A python script (GEnavtoSQL.py) imported shot and CMP navigation from ASCII CSV files (produced in earlier processing steps), projected UTM 19N WGS84 coordinates to Geographic WGS84 using pyProj (version 3.1.0), and the navigation data into a SpatiaLite (version 4.3.0) enabled SQLite (version 3.3.0) database, creating three tables containing point geometries. The first contained records for all shots by line, the second contained records of all CMPs by line, and the third maintained records for the first and last CMPs, and CMPs at multiples of 500 by line. A 500-CMP interval was chosen because it corresponds to the annotation and tick interval provided along the top of the migrated, stacked profile images. The resulting database columns for the shot table consists of East, North (WGS84 UTM19N m), Lon, Lat (WGS84 dd), LineName, FFID, Year, JD_UTC (DDD:HH:MM:SS), SurveyID, VehicleID, and DeviceID. The resulting database columns for the CMP tables consist of East, North (WGS84 UTM18N m), Lon, Lat (WGS84 dd), LineName, ImageName, CMP, Year, SurveyID, VehicleID, and DeviceID. A third table was created to contain trackline geometries generated from the CMP point geometries for each line (sorted by LineName and CMP), and the line length in kilometers was calculated. The resulting database columns of the line geometry table consist of LineName, ImageName, CMP_init, CMP_end, SurveyID, VehicleID, DeviceID, and Length_km.
    Date: Jul-2021 (process 3 of 4)
    PROCESS STEP 3:
    The shot, CMP, and 500 CMP points, and CMP tracklines were added into ArcGIS Pro (version 2.3.3) from the SQLite database (drag and drop from the database in Catalog pane folder connection), then exported (using the Feature Class to Feature Class geoprocessing tool) to the new Esri point and polyline shapefiles '2020-014-FA_MCS_shtnav.shp', '2020-014-FA_MCS_cmpnav.shp', '2020-014-FA_MCS_cmp500.shp', and '2020-014-FA_MCS_cmpTracklines.shp', respectively. The Export Feature Attribute to ASCII geoprocessing tool was used to produce ASCII CSV files from the attribute tables of '2020-014-FA_MCS_shtnav.shp' and '2020-014-FA_MCS_cmpnav.shp'.
    Date: Jun-2021 (process 4 of 4)
    The Seismic Unix (version 4.3) script 'plot_geomet' was used to read the migrated stacked deconvolved SEG-Y files and create variable density greyscale Postscript plots (using the Seismic Unix 'psimage' module) showing two-way travel time (seconds) along the y-axis (left margin) and shots along profile (labeled at 500 CMP intervals) on the x-axis (along top of profile). The Postscript images were then converted to 300 dpi PNG formatted images using ImageMagick convert (version 6.9.3-4). The output PNG files were named according to filename convention with '.psmig.png' indicating post-stack migration.
  3. What similar or related data should the user be aware of?
    Norris, M.W., and Faichney, A.K., 2002, SEG-Y rev. 1 Data Exchange Format - SEG Technical Standards Committee: Society of Exploration Geophysicists, Tulsa, OK.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    Multichannel seismic-reflection shots were navigated using a Hemisphere R131 Differential and WAAS (Wide Angle Augmentation System) enabled GPS receiver, with the navigational reference point (NRP) antenna mounted on the mast atop the wheelhouse of the R/V Sultana. The NRP was located along the vessel centerline 6.13 m from the stern. The sparker sources were towed from the port quarter of the vessel, between 31.13 and 38.93 meters astern of the NRP, and the GeoEel streamer (50 m active section) was towed from a boom on the starboard quarter with the center of the first (channel 1) and last (channel 32) active groups trailing the NRP approximately 52.53 m and 101.9 m respectively. The Geometrics CNT-1 seismic acquisition software (version 5.64) logged the shot navigation coordinates to the SEG-D external header. Processing descriptions provided below outline the procedures for calculating layback distances between the NRP, acoustic source, and receivers into the Common Midpoint (CMP) binning process. Although horizontal accuracy of WAAS enabled DGPS is estimated to be within 2-3 m, we assume the accuracy of the shot positions to be +/- 10 m due to layback offset between the NRP and far offsets of the receivers (there was no tail buoy with GPS) and movement of the source astern of the ship. Accuracy of CMP bin location is assumed to be coarser due to the additional uncertainty added from calculation of source/receiver layback and common midpoint positions.
  3. How accurate are the heights or depths?
    Streamer mounted RBR Solo-D depth loggers estimate receiver depths with the RBR Ltd. Ruskin utility (v2.7.3.201905031233) via the simplified derivation, where depth in meters = (measured pressure in dbar - atmospheric pressure (set to default 10.1325 dbar)) / (density (set to default 1.0281 g/mL) * 0.980665). The RBR Solo-D units used are rated to 20 meters and RBR Ltd. state that they are accurate to +/- 0.05 percent of full scale (about 1 cm water depth).
  4. Where are the gaps in the data? What is missing?
    The shot navigation file '2020-014-FA_MCS_shtnav.csv' contains navigation coordinates for all shot records acquired during the survey except for Line0000, Line0001, and Line 0002 which contained poor quality data acquired during system testing. Line0007a and Line0013 have 335 and 162 CMP traces respectively and are not included in this data release. Additionally, malfunction of the acquisition system and misfire caused multiple failed file initializations prior to eventual success for Line0008c, Line0015b, and Line00017c, which accounts for seemingly nonsequential file naming. Data were collected intermittently between March 7 and 13, 2020. No multichannel seismic data were recorded during transits to and from port. Hiatus between source shots in Line0004a (1657-1658) Line0007 (2496-2499) and Line0011 (2376-2407) resulted from periods of troubleshooting trigger interruption or source timeout, while the same on Line0015b (1710-1717 and 2855-2856) resulted from temporary shutdown for dolphins in the vicinity. FFID numbers do not start at 1 for all files.
  5. How consistent are the relationships among the observations, including topology?
    Quality control was conducted during processing to ensure consistency of stacked CMP SEG-Y data files with corresponding navigation ASCII CSV and shapefiles and seismic profile images. CMP numbers and navigation are consistent between corresponding survey lines files in the SEG-Y ('2020-014-FA_psmig_sgy.zip') and png image ('2020-014-FA_MCS_Images.zip') archives and the navigation files '2020-014-FA_MCS_cmp500.shp', '2020-014-FA_MCS_cmpnav.csv', and '2020-014-FA_MCS_cmpTracklines.shp'. One exception is Line0003 which necessitated the omission of CMPs 5760-5779 from the final stack and png image files. The attribute fields 'LineName' and 'ImageName' for each polyline feature in '2020-014-FA_MCS_cmpTracklines.shp' correspond to the SEG-Y data files in '2020-014-FA_psmig_sgy.zip' and the PNG profile images in '2020-014-FA_MCS_Images.zip', respectively.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints none
Use_Constraints Public domain data from the U.S. Government are freely distributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: GS ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    United States

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? USGS data release of multichannel seismic-reflection data collected using SIG ELC1200 and Applied Acoustics Delta Sparkers and Geometrics GeoEel digital streamers during the USGS field activity 2020-014-FA: includes '2020-014-FA_MCS_cmp500.shp' containing the first, last and 500-interval CMP locations, '2020-014-FA_MCS_cmpnav.csv' containing all CMP locations, '2020-014-FA_MCS_cmpTracklines.shp' containing trackline features, '2020-014-FA_MCS_shtnav.csv' containing shot point locations, the zip archive '2020-014-FA_MCS_Images.zip' containing 19 PNG images (named according to filename convention with '.psmig.png' appended), the zip archive '2020-014-FA_MCS_Segy.zip' containing the post-stack migration CMP traces in binary SEG-Y files (named according to filename convention with '.psmig.sgy' appended), the browse graphic '2020-014-FA_MCSBrowseImage.jpg', and the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file 2020-014-FA_MCS_meta.xml.
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    To utilize these data, the user must have software capable of reading shapefiles, CSV files, PNG images, and/or SEG-Y seismic trace files.

Who wrote the metadata?

Dates:
Last modified: 19-Mar-2024
Metadata author:
U.S. Geological Survey
Attn: Wayne E. Baldwin
Geologist
384 Woods Hole Rd.
Woods Hole, MA

(508) 548-8700 x2226 (voice)
(508) 457-2310 (FAX)
whsc_data_contact@usgs.gov
Contact_Instructions:
The metadata contact email address is a generic address in the event the person is no longer with USGS. (updated on 20240319)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/SB_data_release/DR_P96GY6TQ/2020-014-FA_MCS_meta.faq.html>
Generated by mp version 2.9.51 on Wed Jun 26 15:25:04 2024