Chirp seismic reflection - shotpoints, tracklines, profile images, and SEG-Y traces for EdgeTech SB-424 chirp data collected during USGS field activity 2021-004-FA (point and polyline shapefiles, CSV text, PNG Images, and SEGY data, GCS WGS 84)

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:

What does this data set describe?

Title:
Chirp seismic reflection - shotpoints, tracklines, profile images, and SEG-Y traces for EdgeTech SB-424 chirp data collected during USGS field activity 2021-004-FA (point and polyline shapefiles, CSV text, PNG Images, and SEGY data, GCS WGS 84)
Abstract:
The U.S. Geological Survey (USGS) Woods Hole Coastal and Marine Science Center (WHCMSC) completed a bathymetric and shallow seismic-reflection survey during the period of June 9, 2021 to June 24, 2021 in water depths from 2 m to 30 m for a portion of the outer Cape Cod nearshore environment between Marconi and Nauset Beaches. The products from this survey will help to support white shark research on their shallow-water behavior in the dynamic nearshore environment at Cape Cod National Seashore (CACO). CACO visitors’ safety is threatened by interactions between the public and white sharks. This project provides CACO with baseline data and information on nearshore white shark habitat, specifically in the nearshore shoreface, bathymetric trough, and longshore bar. This data release provides the geophysical data collected from outer Cape Cod during USGS Field Activities 2021-002-FA in 2021.
Supplemental_Information:
Support for 2021-004-FA was provided to the USGS from the National Park Service, Cape Cod National Seashore. Additional information on the field activities associated with this project are available at https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-004-FA
  1. How might this data set be cited?
    Foster, David S., 20231114, Chirp seismic reflection - shotpoints, tracklines, profile images, and SEG-Y traces for EdgeTech SB-424 chirp data collected during USGS field activity 2021-004-FA (point and polyline shapefiles, CSV text, PNG Images, and SEGY data, GCS WGS 84): data release DOI:10.5066/P9GO90TI, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Ackerman, Seth D., Foster, David S., Worley, Charles R., and Nichols, Alexander R., 2023, High-resolution geophysical and geological data collected from outer Cape Cod, Massachusetts during USGS Field Activity 2021-004-FA: data release DOI:10.5066/P9GO90TI, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Ackerman, S.D., Foster, D.S., Worley, C.R., and Nichols, A.R., 2023, High-resolution geophysical and geological data collected from outer Cape Cod, Massachusetts during USGS Field Activity 2021-004-FA: U.S. Geological Survey data release, https://doi.org/10.5066/P9GO90TI.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -69.977142
    East_Bounding_Coordinate: -69.915425
    North_Bounding_Coordinate: 41.942144
    South_Bounding_Coordinate: 41.78285
  3. What does it look like?
    https://cmgds.marine.usgs.gov/data-releases/media/2022/10.5066-P9GO90TI/f5a2ef99418a4c0897c1871ab811c086/2021-004-FA_SB424Tracklines_browse.jpg (JPEG)
    chirp seismic-reflection navigation trackline.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 09-Jun-2021
    Ending_Date: 24-Jun-2021
    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?
    2021-004-FA_SB424Tracklines.shp
    SB-424 Trackline shapefile for survey 2021-004-FA (93 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: Area_Line-FileNumber (e.g., 'MB_Line-0001'). Area MB = Marconi Beach and Area NB = Nauset Beach. (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
    Shot_init
    Shot number at the start of the survey line. (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:4950
    Units:shot
    Resolution:1
    Shot_end
    Shot number at the end of the survey line. (Source: U.S. Geological Survey)
    Range of values
    Minimum:316
    Maximum:17912
    Units:shot
    Resolution:1
    Year
    Calendar year the data were collected (Source: U.S. Geological Survey) Character set
    JD_UTC_ini
    Julian day and UTC time at the start of the survey line in the format: JD: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
    JD_UTC_end
    Julian day and UTC time at the end of the survey line in the format: JD: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., "2021-004-FA" where 2021 is the survey year, 004 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
    Sonar device used to collect seismic-reflection data. (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:0.208
    Maximum:12.216
    Units:kilometers
    Resolution:0.001
    2021-004-FA_SB424sht500.shp
    SB424 500-interval shot point shapefile for survey 2021-004-FA (1149 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:418995.94
    Maximum:423992.93
    Units:meters
    Resolution:.01
    North
    Northing coordinate in UTM Zone 19 N meters, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:4626081.95
    Maximum:4643794.43
    Units:meters
    Resolution:.01
    Lon
    Longitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:-69.915425
    Maximum:-69.977142
    Units:degrees
    Resolution:1E-06
    Lat
    Latitude coordinate in decimal degrees, WGS 84 (Source: U.S. Geological Survey)
    Range of values
    Minimum:41.78285
    Maximum:41.942144
    Units:degrees
    Resolution:1E-06
    LineName
    Name of the trackline along which seismic-reflection data were collected in the format: Area_Line-FileNumber (e.g., 'MB_Line-0001'). (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
    Shot
    Shot number (values are first, last, and every 500 shot between). (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:17912
    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 first, last, and every 500 shot point between of the survey line in the format: JD: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., "2021-004-FA" where 2021 is the survey year, 004 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
    Sonar device used to collect seismic-reflection data. (Source: U.S. Geological Survey) Character set
    2021-004-FA_SB424_shtnav.csv
    SB424 shot point comma separated values file for survey 2021-004-FA (499910 point features). The fields of this CSV file are the same as the shapefile attributes described above (East,North,Lon,Lat,LineName,ImageName,Shot,Year,JD_UTC,SurveyID,VehicleID,DeviceID) (Source: U.S. Geological Survey)
    Entity_and_Attribute_Overview:
    The column headings and range domain values in '2021-004-FA_SB424_shtnav.csv' match those in '2021-004-FA_SB424sht500.shp'. The PNG seismic reflection images can be hyperlinked to their corresponding trackline or shotpoint locations in ArcGIS using the shapefiles '2021-004-FA_SB424Tracklines.shp' or '2021-004-FA_SB424sht500.shp', respectively. The fist, last, and multiple of 500 shot features in '2021-004-FA_SB424sht500.shp' correspond to the x-axis ticks on the PNG images, which show two-way travel time (seconds) on the y-axis and distance along profile (annotation at 500 shot intervals) on the x-axis.
    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)
    • David S. Foster
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    David S. Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, Massachusetts
    US

    508-548-8700 x2271 (voice)
    508-457-2310 (FAX)
    dfoster@usgs.gov

Why was the data set created?

This dataset contains shotpoint and trackline navigation, profile images, and raw SEG-Y trace data for approximately 358 km of EdgeTech SB424 chirp seismic-reflection data collected by the U.S. Geological Survey during USGS field activity 2021-004-FA from outer Cape Cod. 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 '2021-002-FA_SB424Tracklines.shp'. Shotpoint index and tick marks along the top of the PNG images correlate to the positions of 500 shot intervals within the Esri point shapefile '2021-004-FA_SB424sht500.shp'. This information allows for spatial correlation of chirp seismic-reflection profiles images with other geophysical 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?
    SEG-Y SB-424 data (source 1 of 1)
    U.S. Geological Survey, unpublished material, SB-424 SEG-Y trace data.

    Type_of_Source_Media: disc
    Source_Contribution:
    The EdgeTech SB-424 subbottom profiler tow vehicle was pole mounted on the port aft quarter of the RV Rafael. The transducers were 1 m below the water line, and approximately 1 meter astern of the DGPS antenna mounted on the cabin top. Chirp seismic data were collected using an EdgeTech Geo-Star FSSB sub-bottom profiling system and an SB-424 towfish. SonarWiz 7 (version 7.07.06) seismic acquisition software was used to control the Geo-Star FSSB topside unit, digitally log three trace data (envelope, real, and imaginary) in the SEG-Y Rev. 1 format (IEEE floating point), and record GPS navigation coordinates to the SEG-Y trace headers (in arc seconds of Latitude and Longitude, multiplied by a scalar of 100). SonarWiz recorded heave values from the heave, pitch, and roll data that came from the POSMV IMU to the SEG-Y header bytes 189-190 as 16-bit integer in cm*10 units. Data were acquired using 25-ms shot rates, a 10-ms pulse length, and a 4 to 20 kHz frequency sweep. Traces were recorded with a 23-microsecond sample interval with a trace length of 100 ms.
  2. How were the data generated, processed, and modified?
    Date: 04-Mar-2022 (process 1 of 4)
    PROCESS STEP 1: Shearwater Reveal (version 4.1), and Python 2.7.6 were used to process SEG-Y data and extract navigation data. The processing flows and scripts used are summarized below and in the following processing steps.
    1) The Reveal flow 001_ read424_segy.flow called the module SegyTapeRead that reads the raw SEG-Y files containing the envelope, real, and imaginary trace data. The following SEG-Y trace headers were mapped and saved as Reveal headers: FFID, Channel, Source X and Y, Year, Day, Hour, Minute, Second, and Heave (derived from POS MV IMU) in bytes 189-190 (16-bit integer). HeaderMath and UTMLatLong converted the navigation reference point (NRP) lat/lon positions from seconds of arc to decimal degrees, projected them to UTM Zone 19N WGS 84 meters, and wrote each to new header words (NRP_LAT, NRP_LON, NRP_X, and NRP_Y). Finally, Output wrote the envelope-detected traces and the real traces to separate new files '*.seis' in the internal Reveal format.
    2) The Reveal flow 002_layback_stat.flow applied static corrections to account for a draft depth (1 m) of the SB-424 pole-mounted tow vehicle and to remove heave. The heave from the Reveal header Heave (cm*10) was converted using HeaderMath to two-way travel time (TWT) milliseconds (ms) by dividing by -750 (assumes a velocity of 1500 m/s and account for negative values are down in the POSMV data). ApplyStatic shifted the trace data from the converted TWT heave values. File MB_Line-0001, MB_Line-0002, MB_Line-0003, MB_Line-0003a, MB_Line-0003b. MB_Line-0004, MB_Line-0004a, and MB_Transit-0001 did not have values for heave in the raw SEG-Y files. For these files, a custom Python module ObspyPicking was used to pick the sea floor. HeaderFiltering was used to apply a 51 trace smoothing filter to the sea floor picks. ApplyStatic used the difference between the picked sea floor and the smoothed sea floor was used to shift and remove heave effects.
    The Reveal flow 002_layback_stat.flow also applied the custom Python module ShotlineLayback (developed by Nathan Miller of USGS-WHCMSC) defined the horizontal offset between the GPS antenna and the pole-mounted SB-424( approximately 1 m astern). The algorithm interpolated a sail line from the navigation reference point positions (NRP_X and NRP_Y), then computed layback positions for the shots by translating them back along the sail line by the total offset and wrote the calculated layback positions to new header words (SRC_X, SRC_Y, REC_X, REC_Y). UTMLatLong converted the layback positions from UTM Zone 19N WGS 84 meters to decimal degrees and wrote each to new header words (NRP_LAT, NRP_LON, SRC_LAT, SRC_LON, REC_LAT, and REC_LON). HeaderMath converted the layback REC_LAT and REC_LON values from decimal degrees to seconds of arc with a scalar of 100, and set header words for navigation coordinate units (geographic seconds of arc with scalar) and time basis code (UTC). Output wrote the processed traces to new SEG-Y and Reveal seis format files that included static corrections and layback positions.
    3) The static and layback corrected SEG-Y files were imported to Kingdom Suite (v. 2017) using the layback navigation. The sea-floor reflection was picked using 2Dhunt and manually edited when needed. The picked sea floor was exported as CSV files with columns File Name, FFID, and two-way travel time. Grep was used to select individual records by File Name and write individual CSV files for each file. The Reveal flow 003_chirp_gain used the module DBMerge matched FFID in the CSV files with the Reveal FFID headers and created a new Reveal header for the sea floor picks (SFTWT). HeaderMath converted the SFTWT two-way travel time in seconds to a new header SFTWT_MS in milliseconds (ms).
    4) The Reveal module TraceMath applied a time-dependent gain function relative to the header SFT_MS. TraceMath supports the special variables SAMPLE and TIME where SAMPLE is the value of each input sample and the variable TIME to the z coordinate of the trace in ms. The following equation was applied: sample = ifelse(TIME > SFTWT_MS - 3, sample * pow((TIME-(SFTWT_MS-3))/1000,1), 0) The function pow(a, b) where a=TIME-(SFTWT_MS-1)/1000 is raised to the power of b (1). New SEG-Y and Reveal files were written with the gain function applied.
    5) A Seismic Unix (version 4.2) script read424 was used to read the gain applied SEG-Y files with the gain function applied. The layback corrected coordinates were extracted from SEG-Y headers and written to a Seismic Unix file. Along with the extracted coordinates, other SEG-Y trace header information, including shot number, year, Julian day, and time of day (UTC) were extracted. Header information from each SEG-Y file was saved to text files after an AWK (no version) filter was used to maintain the first and last shots, shots at multiples of 500 and shots with unique navigation coordinates. Geographic coordinates (WGS 84) were converted to UTM zone 19 N coordinates (WGS 84) using Proj (version 4.6.0). End shots and shots at multiples of 500 may not have unique navigation coordinates. Separate text files containing the first and last shots and even 500 shot intervals were also saved. A 500 shot interval was chosen because it corresponds to the annotation interval provided along the top of the seismic-reflection profile images. Read424 called a Python script 424itoSQL_21004.py, written by Wayne Baldwin, which imported the CSV files to a Spatialite (version 4.3.0) enabled SQLite (version 3.21.0) database, creating three tables containing point geometries for the unique and 500 shotpoint navigation and trackline features.
    These process steps and all subsequent process steps were conducted by the same person - David S. Foster. 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: 04-Mar-2022 (process 2 of 4)
    PROCESS STEP 2: The SB-424 500 shot and trackline features were added (Add Data) into ArcGIS Pro (version 2.4.1) from the SQLite database, then exported with the Geoprocessing, Feature Class To Shapefile tool to new Esri polyline shapefiles '2021-004-FA_SB424_sht500.shp' and '2021-004-FA_SB424Tracklines.shp', respectively.
    Date: 08-Mar-2022 (process 3 of 4)
    PROCESS STEP 3: The Seismic Unix (version 4.2), script Plot424 created variable density postscript plots of the seismic profiles showing two-way travel time (seconds) along the y-axis (left margin) and shots along profile (labeled at 500 shot intervals) on the x-axis (along top of profile). The postscript images were converted to 200 dpi portable network graphic (PNG) images using ImageMagick (version 7.0.10-37). The plots are labeled along the bottom of the X axis. Plots with fewer than approximately 1000 traces may have truncated x-axis labels.
    Date: 14-Nov-2022 (process 4 of 4)
    PROCESS STEP 4: The SEGY data were updated to include the publication DOI url in the headers.
  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?
    The EdgeTech SB-424 subbottom profiler tow vehicle was pole mounted on the port aft quarter of the RV Rafael. The transducers were 1 m below the water line, and approximately 1 meter astern of the DGPS antenna mounted aft on the cabin top. Navigation data for the SB-424 were collected using a Hemisphere DGPS receiver with the antenna mounted on the aft main cabin top. Positioning data were recorded using SonarWiz 7 (version 7.07.06) acquisition software, which logged geographic coordinates to individual trace headers in SEG-Y format. DGPS horizontal positional accuracy is assumed to be within 2 m.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Sections of tracklines where navigation was recorded but no seismic data were logged are not included such as during testing, some turns, and very short files.
  5. How consistent are the relationships among the observations, including topology?
    Chirp seismic-reflection data were collected from June 9 through 24. '2021-004-FA_SB424sht500.shp' contains the first, last, and 500-interval shotpoints for each seismic trackline, and '2021-004-FA_SB424_shtnav.csv' contains all unique shot point navigation. The attribute fields 'LineName' and 'ImageName' for each polyline feature in '2021-004-FA_SB424Tracklines.shp' correspond to the SEG-Y data files in '2021-004-FA_SB424_SegyData.zip' and the PNG profile images in "2021-004-FA_SB424_Images.zip", respectively. One SEG-Y file, and PNG image exists for each feature. Processed seismic data were converted to PNG format for ease of seismic trace display. Quality control was conducted during processing.

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: Coastal and Marine Hazards and Resources Program
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    whsc_data_contact@usgs.gov
  2. What's the catalog number I need to order this data set? USGS data release of EdgeTech SB424 chirp seismic-reflection data collected in outer Cape Cod during USGS field activity 2021-004-FA: includes '2021-004-FA_SB424sht500.shp' containing the first, last and 500-interval shotpoint locations, '2021-004-FA_SB424shtnav.csv' containing unique shot point locations, '2021-004-FA_SB424Tracklines.shp' containing trackline features, '2021-004-FA_SB424_Images.zip' containing 616 PNG images named according to line convention, '2021-004-FA_SB424_SegyData.zip' containing 93 SEG-Y files of the processed traces, the browse graphic 2021-004-FA_SB424Tracklines_browse.jpg, and Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (CSDGM) metadata file '2021-004-FA_SB424_meta.xml'. These datasets can be downloaded individually (see the Digital Transfer Option section).
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
  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: 14-Nov-2023
Metadata author:
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)
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 the USGS.
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/DRB_data_release/DRB_P9GO90TI/2021-004-FA_SB424_meta.faq.html>
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