Marine sparker SEG-Y seismic data recorded aboard the R/V San Lorenzo using receive hydrophones during USGS field activity 2021-619-FA offshore Santa Cruz, California in April of 2021

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Frequently anticipated questions:

What does this data set describe?

Title:
Marine sparker SEG-Y seismic data recorded aboard the R/V San Lorenzo using receive hydrophones during USGS field activity 2021-619-FA offshore Santa Cruz, California in April of 2021
Abstract:
Seismic data were recorded from the R/V San Lorenzo (RVSL; receive vessel) of a two-vessel marine sparker seismic survey conducted by the U.S. Geological Survey (USGS) in April of 2021 off the coast of Santa Cruz, California (USGS field activity 2021-619-FA). The R/V Parke Snavely (RVPS; source vessel) towed a marine sparker sound source along seven depth site transects ranging between 25 and 600 meters. The RVSL maintained a nearly stationary position at the midpoint of each transect and recorded sound data with a broadband omnidirectional Cetacean Research CR3 hydrophone positioned between 10- and 20-meters water depth below the RVSL. RVSL receive seismic data are presented in SEG-Y format. Shot point navigation are provided in an accompanying comma-delimited text file, as well as in a shapefile for visualization purposes. Navigation data for the source and receiver vessels, as well as seismic data from the source vessel, sound velocity, and other survey data, are provided elsewhere in this data release.
Supplemental_Information:
Additional information about the field activities from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-619-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Balster-Gee, Alicia F., Baldwin, Wayne E., and Hart, Patrick E., 20220920, Marine sparker SEG-Y seismic data recorded aboard the R/V San Lorenzo using receive hydrophones during USGS field activity 2021-619-FA offshore Santa Cruz, California in April of 2021: data release DOI:10.5066/P9EHITBI, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Balster-Gee, Alicia F., Baldwin, Wayne E., and Hart, Patrick E., 2022, Calibrated marine sparker source amplitude decay versus offset offshore Santa Cruz, California: data release DOI:10.5066/P9EHITBI, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -122.338
    East_Bounding_Coordinate: -121.925
    North_Bounding_Coordinate: 36.9759
    South_Bounding_Coordinate: 36.7788
  3. What does it look like?
    2021-619-FA_receive_SEG-Y_L200_b.png (PNG)
    Image of seismic line recorded aboard the nearly stationary receive vessel (R/V San Lorenzo; RVSL) as the source vessel (R/V Parke Snavely; RVPS) transited along the L200 pass ‘b’ trackline while firing the with the SIG ELP790 sparker source (power 700 joules). Peak amplitudes per trace are shown in green.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 19-Apr-2021
    Ending_Date: 28-Apr-2021
    Currentness_Reference:
    ground condition at time data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: seismic-reflection data in SEG-Y format
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point (21819)
    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.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Local surface
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    2021-619-FA_RVSL_RecSegy.zip
    Zip archive of seismic shots with time stamp in standard SEG-Y file format (Source: Society of Exploration Geophysicists (SEG) Technical Standards, available for download at http://seg.org/Publications/SEG-Technical-Standards)
    2021-619-FA_RVSL_RecSegyNav.csv
    SEG-Y shot point navigation and associated attributes. The first line of the csv file is a header line. (Source: U.S. Geological Survey)
    filename
    Name of navigation line (Source: Assigned unique line identifier name)
    ValueDefinition
    SL-L25_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site
    SL-L25_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site
    SL-L25_S_cPass ‘c’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site
    SL-L25A_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the second 25-meter depth site ‘25A’
    SL-L25A_S_a2Pass ‘a2’ (part two of pass a) with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site ‘25A’
    SL-L25A_S_a3Pass ‘a3’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site ‘25A’
    SL-L25A_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site ‘25A’
    SL-L50_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site
    SL-L50_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site
    SL-L50A_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site ‘50A'
    SL-L50A_S_a2Pass ‘a2’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site ‘50A’
    SL-L50A_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site ‘50A’
    SL-L100_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 100-meter depth site
    SL-L100_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 100-meter depth site
    SL-L100_S_cPass ‘c’ with the SIG ELP790 minisparker source (power 700 joules) at the 100-meter depth site
    PS-L100_S_c2Pass ‘c2’ with the SIG ELP790 minisparker source (power 700 joules) at the 100-meter depth site
    PS-L200_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 200-meter depth site
    PS-L200_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 200-meter depth site
    PS-L200_S_cPass ‘c’ with the SIG ELP790 minisparker source (power 700 joules) at the 200-meter depth site
    PS-L200_D10_aPass ‘a’ with the Delta sparker source (power 1.0 kilojoules) at the 200-meter depth site
    PS-L200_D10_bPass ‘b’ with the Delta sparker source (power 1.0 kilojoules) at the 200-meter depth site
    PS-L200_D10_cPass ‘c’ with the Delta sparker source (power 1.0 kilojoules) at the 200-meter depth site
    PS-L200_D10_dPass ‘d’ with the Delta sparker source (power 1.0 kilojoules) at the 200-meter depth site Enumerated_Domain_Value_Definition_Source: Producer defined
    PS-L600_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 600-meter depth site
    PS-L600_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 600-meter depth site
    PS-L600_D24_aPass ‘a’ with the Delta sparker source (power 2.4 kilojoules) at the 600-meter depth site
    PS-L600_D24_bPass ‘b’ with the Delta sparker source (power 2.4 kilojoules) at the 600-meter depth site
    hpid
    Hydrophone Identifier (Source: producer defined) model number CR3101 (Cetacean Research) model number CR3102 (Cetacean Research)
    lbsrc_lon
    longitude of the sparker source layback position from the stern of the source vessel (RVPS) (Source: producer defined)
    Range of values
    Minimum:-122.361232
    Maximum:-121.897050
    Units:decimal degrees
    Resolution:0.000001
    lbsrc_lat
    latitude of the sparker source layback position from the stern of the source vessel (RVPS) (Source: producer defined)
    Range of values
    Minimum:36.763453
    Maximum:36.992548
    Units:decimal degrees
    Resolution:0.000001
    rec_lon
    longitude of the RVSL hydrophone receiver (Source: producer defined)
    Range of values
    Minimum:-122.337685
    Maximum:-121.924577
    Units:decimal degrees
    Resolution:0.000001
    rec_lat
    latitude of the RVSL hydrophone receiver (Source: producer defined)
    Range of values
    Minimum:36.778768
    Maximum:36.975878
    Units:decimal degrees
    Resolution:0.000001
    signoffset
    offset distance between the layback position of the sparker source off the stern of the RVPS source vessel and the RVSL hydrophone receiver . Positive values are when the source is northwest of the receiver and negative when the source is southeast of the receiver (Source: producer defined)
    Range of values
    Minimum:-5440
    Maximum:4733
    Units:meters
    Resolution:1
    y
    Year collected (Source: time stamp from GGA navigation string from receive vessel R/V San Lorenzo)
    Range of values
    Minimum:2021
    Maximum:2021
    Units:year collected
    Resolution:1
    jd
    Julian Day collected (Source: time stamp from GGA navigation string from receive vessel (RVSL))
    Range of values
    Minimum:111
    Maximum:119
    Units:Julian day collected
    Resolution:1
    h
    hour collected (Source: time stamp from GGA navigation string from receive vessel (RVSL))
    Range of values
    Minimum:14
    Maximum:20
    Units:hour of day collected
    Resolution:1
    m
    minute collected (Source: time stamp from GGA navigation string from receive vessel (RVSL))
    Range of values
    Minimum:0
    Maximum:59
    Units:minute of hour collected
    Resolution:1
    s
    second collected (Source: time stamp from GGA navigation string from receive vessel (RVSL))
    Range of values
    Minimum:0
    Maximum:59
    Units:second of minute collected
    Resolution:1
    us
    microsecond collected (Source: time stamp from GGA navigation string from receive vessel (RVSL))
    Range of values
    Minimum:68156
    Maximum:932070
    Units:microsecond of second of minute collected
    Resolution:1
    utc_dt
    Coordinated Universal Time (UTC) Day Time string (Source: producer defined) Sequential unique whole numbers that are automatically generated. For example, 2021-04-23 18:31:02.999936+00:00 represents 2021-04-23 as the date collected and 18:31:02.999936+00:00 is the UTC time that the navigation point was taken.
    surveyid
    USGS field activity number (FAN) assigned to data collection activity (Source: producer defined) 2021-619-FA, details for which may be found at https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-619-FA
    vehicleid
    name of the vessel from which data was collected (Source: producer defined) R/V San Lorenzo
    deviceid
    Sparker source type and power level (in joules) (Source: producer defined)
    ValueDefinition
    Applied Acoustics Delta Sparker (2400 J)Brand name and model of sparker source and power level measured in joules
    Applied Acoustics Delta Sparker (1000 J)Brand name and model of sparker source and power level measured in joules
    SIG ELP790 Sparker (700 J)Brand name and model of sparker source and power level measured in joules
    2021-619-FA_RVSL_RecSegyNav_shapefile.zip
    Zip file contains a point shapefile (.shp) of the location of each SEG-Y shot point along the navigated tracklines of the receiver vessel (R/V San Lorenzo; RVSL) and associated files (Source: U.S. Geological Survey)
    filename
    Name of navigation line (Source: Assigned unique line identifier name)
    ValueDefinition
    SL-L25_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site
    SL-L25_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site
    SL-L25_S_cPass ‘c’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site
    SL-L25A_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the second 25-meter depth site ‘25A’
    SL-L25A_S_a2Pass ‘a2’ (part two of pass a) with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site ‘25A’
    SL-L25A_S_a3Pass ‘a3’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site ‘25A’
    SL-L25A_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 25-meter depth site ‘25A’
    SL-L50_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site
    SL-L50_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site
    SL-L50A_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site ‘50A'
    SL-L50A_S_a2Pass ‘a2’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site ‘50A’
    SL-L50A_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 50-meter depth site ‘50A’
    SL-L100_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 100-meter depth site
    SL-L100_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 100-meter depth site
    SL-L100_S_cPass ‘c’ with the SIG ELP790 minisparker source (power 700 joules) at the 100-meter depth site
    PS-L100_S_c2Pass ‘c2’ with the SIG ELP790 minisparker source (power 700 joules) at the 100-meter depth site
    PS-L200_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 200-meter depth site
    PS-L200_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 200-meter depth site
    PS-L200_S_cPass ‘c’ with the SIG ELP790 minisparker source (power 700 joules) at the 200-meter depth site
    PS-L200_D10_aPass ‘a’ with the Delta sparker source (power 1.0 kilojoules) at the 200-meter depth site
    PS-L200_D10_bPass ‘b’ with the Delta sparker source (power 1.0 kilojoules) at the 200-meter depth site
    PS-L200_D10_cPass ‘c’ with the Delta sparker source (power 1.0 kilojoules) at the 200-meter depth site
    PS-L200_D10_dPass ‘d’ with the Delta sparker source (power 1.0 kilojoules) at the 200-meter depth site Enumerated_Domain_Value_Definition_Source: Producer defined
    PS-L600_S_aPass ‘a’ with the SIG ELP790 minisparker source (power 700 joules) at the 600-meter depth site
    PS-L600_S_bPass ‘b’ with the SIG ELP790 minisparker source (power 700 joules) at the 600-meter depth site
    PS-L600_D24_aPass ‘a’ with the Delta sparker source (power 2.4 kilojoules) at the 600-meter depth site
    PS-L600_D24_bPass ‘b’ with the Delta sparker source (power 2.4 kilojoules) at the 600-meter depth site
    hpid
    Hydrophone Identifier (Source: producer defined) model number CR3101 (Cetacean Research) model number CR3102 (Cetacean Research)
    lbsrc_lon
    longitude of the sparker source layback position from the stern of the source vessel (RVPS) (Source: producer defined)
    Range of values
    Minimum:-122.361232
    Maximum:-121.897050
    Units:decimal degrees
    Resolution:0.000001
    lbsrc_lat
    latitude of the sparker source layback position from the stern of the source vessel (RVPS) (Source: producer defined)
    Range of values
    Minimum:36.763453
    Maximum:36.992548
    Units:decimal degrees
    Resolution:0.000001
    rec_lon
    longitude of the RVSL hydrophone receiver (Source: producer defined)
    Range of values
    Minimum:-122.337685
    Maximum:-121.924577
    Units:decimal degrees
    Resolution:0.000001
    rec_lat
    latitude of the RVSL hydrophone receiver (Source: producer defined)
    Range of values
    Minimum:36.778768
    Maximum:36.975878
    Units:decimal degrees
    Resolution:0.000001
    signoffset
    offset distance between the layback position of the sparker source off the stern of the source vessel RVPS and the RVSL hydrophone receiver . Positive values are when the source is northwest of the receiver and negative when the source is southeast of the receiver (Source: producer defined)
    Range of values
    Minimum:-5440
    Maximum:4733
    Units:meters
    Resolution:1
    y
    Year collected (Source: time stamp from GGA navigation string from receive vessel R/V San Lorenzo)
    Range of values
    Minimum:2021
    Maximum:2021
    Units:year collected
    Resolution:1
    jd
    Julian Day collected (Source: time stamp from GGA navigation string from receiver vessel (RVSL))
    Range of values
    Minimum:111
    Maximum:119
    Units:Julian day collected
    Resolution:1
    h
    hour collected (Source: time stamp from GGA navigation string from receiver vessel (RVSL))
    Range of values
    Minimum:14
    Maximum:20
    Units:hour of day collected
    Resolution:1
    m
    minute collected (Source: time stamp from GGA navigation string from receiver vessel (RVSL))
    Range of values
    Minimum:0
    Maximum:59
    Units:minute of hour collected
    Resolution:1
    s
    second collected (Source: time stamp from GGA navigation string from receiver vessel (RVSL))
    Range of values
    Minimum:0
    Maximum:59
    Units:second of minute collected
    Resolution:1
    us
    microsecond collected (Source: time stamp from GGA navigation string from receiver vessel (RVSL))
    Range of values
    Minimum:68156
    Maximum:932070
    Units:microsecond of second of minute collected
    Resolution:1
    utc_dt
    Coordinated Universal Time (UTC) Day Time string (Source: producer defined) Sequential unique whole numbers that are automatically generated. For example, 2021-04-23 18:31:02.999936+00:00 represents 2021-04-23 as the date collected and 18:31:02.999936+00:00 is the UTC time that the navigation point was taken
    surveyid
    USGS field activity number (FAN) assigned to data collection activity (Source: producer defined) 2021-619-FA, details for which may be found at https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-619-FA
    vehicleid
    name of the vessel from which data was collected (Source: producer defined) R/V San Lorenzo
    deviceid
    Sparker source type and power level (in joules) (Source: producer defined)
    ValueDefinition
    Applied Acoustics Delta Sparker (2400 J)Brand name and model of sparker source and power level measured in joules
    Applied Acoustics Delta Sparker (1000 J)Brand name and model of sparker source and power level measured in joules
    SIG ELP790 Sparker (700 J)Brand name and model of sparker source and power level measured in joules
    Entity_and_Attribute_Overview:
    Sparker source data in SEG-Y format, with shot-point navigation presented in both shapefile and csv file formats.
    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)
    • Alicia F. Balster-Gee
    • Wayne E. Baldwin
    • Patrick E. Hart
  2. Who also contributed to the data set?
    The authors acknowledge our fellow participants of the sparker testing field activity 2021-619-FA (Pete Dal Ferro, Gerry Hatcher, Jared Kluesner, Rachel Marcuson, Jenny McKee, Dan Powers and Rob Wyland) and our team involved in survey planning and execution (Jackson Currie, William Danforth, Jane Denny, Tim Elfers, Dave Foster, Nathan Miller, Eric Moore and Carolyn Ruppel).
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

This two-vessel survey was designed to quantify the decay of sound emitted from the SIG ELP790 minisparker (powered at 700 joules) and from the Applied Acoustics Delta Sparker (powered at 1.0 and 2.4 kilojoules) as a function of distance during marine geophysical surveys. Seven transect sites were surveyed at five different water depths (25, 50, 100, 200, and 600 meters) to compare the effects of water depth on peak sound level. The source vessel (RVPS) towed the sparker sound source as well as a calibrated hydrophone (TC4034) to record the near-field outgoing signal along the transects. The receive vessel (RVSL) maintained a nearly stationary position at the midpoint of each transect and continuously recorded sound with a calibrated hydrophone (CR3101 or CR3102) at depths between 10 and 20 meters, depending on deployed cable length.

How was the data set created?

  1. From what previous works were the data drawn?
    SrcNav (source 1 of 3)
    Balster-Gee, Alicia F., Baldwin, Wayne E, and Hart, Patrick E., 2022, R/V Parke Snavely (source vessel) navigation and survey geometry from USGS field activity 2021-619-FA collected in April of 2021 offshore Santa Cruz, CA: U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    Type_of_Source_Media: online data
    Source_Contribution:
    Navigation from the source vessel was used to calculated the offset between the RVPS sparker source and the hydrophone on the RVSL receive vessel
    RecNav (source 2 of 3)
    Balster-Gee, Alicia F., Baldwin, Wayne E, and Hart, Patrick E., 2022, R/V San Lorenzo (receiver vessel) navigation and survey geometry from USGS field activity 2021-619-FA collected in April of 2021 offshore Santa Cruz, CA: U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    Type_of_Source_Media: online data
    Source_Contribution:
    Navigation from the RVSL receive vessel was used to calculated the offset between the RVPS sparker source and the hydrophone on the receive vessel
    SrcSegy (source 3 of 3)
    Balster-Gee, Alicia F., Baldwin, Wayne E, and Hart, Patrick E., 2022, Marine sparker source SEG-Y seismic data recorded aboard the R/V Parke Snavely during USGS field activity 2021-619-FA offshore Santa Cruz, California in April of 2021: U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    Type_of_Source_Media: online data
    Source_Contribution:
    SEG-Y data from the near-field hydrophone on the source vessel (RVPS)
  2. How were the data generated, processed, and modified?
    Date: 27-Apr-2021 (process 1 of 4)
    A sparker source (either the SIG ELP790 or the Applied Acoustics Delta Sparker) was towed on a 20-meter cable from the stern of the source vessel (R/V Parke Snavely; RVPS) along seven planned survey tracklines in water depths ranging from 25 to 600 meters. The SIG ELP790 sparker was powered at 700 joules at all water depths. The Applied Acoustics Delta Sparker was powered at 1000 joules at the 200-meter depth site and powered at 2.4 kilojoules at the 600-meter depth site. A Reson TC4034 hydrophone and an RBR depth logger were towed on a second cable and positioned in the water just below the sparker to measure the near-field outgoing source signal and depth. Continuous waveform data (TDMS format) from the near-field hydrophone were acquired using SignalExpress software sampling at 192 kHz. A unique code name was given to each navigation line where PS=the source vessel R/V Parke Snavely; L=line followed by 2- or 3-numerals representing the water depth (the water depth may be followed by an A denoting a planned replicate transect line); S=SIG ELP790 700-joule minisparker source, D10=1.2 kilojoule Delta sparker source, or D24=2.4 kilojoule Delta sparker source; subsequent passes are followed with a, b, c, d, and a numeral as needed. Navigation data aboard the source vessel were acquired using an Applanix PosMV Elite differential Global Positioning System (DGPS). The source vessel navigation data (SrcNav) and outgoing source signal data (SrcSegy) are provided elsewhere in this data release.
    Date: 27-Apr-2021 (process 2 of 4)
    The receiver vessel (R/V San Lorenzo; RVSL), maintained a nearly stationary position at the midpoint of each trackline and recorded the signal on one or two Cetacean Research CR3 omnidirectional hydrophones (CR3101 and CR3102) deployed mid-vessel between 10 and 20-meters water depth. The CR3 hydrophones recorded continuous waveform data (.wav format) using SpectraPlus software sampling at 192 KHz. RBR Solo-D depth loggers were positioned near the hydrophones to record the receiver hydrophone depth data (HPdepth_m column when available). Navigation data for the receiver vessel (RecNav) were acquired with a Garmin GPSMAP 4212 Differential Global Positioning System (DGPS) and are provided elsewhere in this data release.
    Date: 27-Apr-2021 (process 3 of 4)
    Navigational data from both the RVPS source and RVSL receiver vessels were recorded in raw GGA format. The UTC timestamp, latitude and longitude were extracted using a series of Python notebooks. The layback position of the sparker source was estimated to be 20 meters from the stern of the source vessel. The python tool PyProj.Geod WGS84 was used to merge the data frames of the source layback latitude and longitude positions (lbsrc_lat and lbsrc_lon, respectively) and to calculate and assign the offset distance, in meters, between the sparker source and the RVSL receive hydrophone for each UTC time sample (utc_dt). To orient the offsets from separate passes relative to each other, a signed offset (signoffet) value was assigned which is the source offset value in meters that is positive when the RVPS is northwest of the RVSL and negative when the RVPS is southeast of the RVSL. Data sources used in this process:
    • SrcNav
    • RecNav
    Date: 27-Apr-2022 (process 4 of 4)
    SignalExpress software was used to output TDMS float files from the Reson TC4034 hydrophone on the source vessel (RVPS). The python package npTDMSb (https://nptdms.readthedocs.io/en/stable/apireference.html#module-nptdms) was used to read the recorded hydrophone float voltage and write to an ObsPy trace (https://docs.obspy.org). Aboard the receiver vessel (RVSL), SpectraPlus .wav files were output in 16-bit format from the Cetacean Research model CR3 receiver hydrophones. ObsPy and NumPy (https://numpy.org) python packages were used to unscale the 16-bit voltage readings to float format ObsPy traces. For each pass at each depth site, the timing of the electromagnetic spike as the power supply (aboard the source vessel) discharges power to the sparker source relative to the nearest offset shot time was used to shift the continuous waveform start time. For both source and receive ObsPy traces a 70-7000Hz bandpass filter was applied. ObsPy traces were sliced from the continuous waveform using the shot timing (record lengths for RVPS SEG-Y are 0.2 seconds and the RVSL SEG-Y are 2 seconds with offset dependent start times written to the Delay Recording time DELRT header in header bytes 109-110), resampled to 16 kHz, and standard SEG-Y headers were written (https://seg.org/Portals/0/SEG/News%20and%20Resources/Technical%20Standards/seg_y_rev1.pdf). The receiver vessel navigation, shot times, and RBR hydrophone depths (when recorded) were written to SEG-Y headers (2021-619-FA_RVSL_RecSegy.zip). A CSV file that contains source vessel shot point navigation, offset, shot times, vessel, device, and SEG-Y filename summary information was created (2021-619-FA_RVSL_RecSegyNav.csv), along with a shapefile of shot point navigation for visual purposes (2021-619-FA_RVSL_RecSegyNav_shapefile.zip).
  3. What similar or related data should the user be aware of?

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

  1. How well have the observations been checked?
    Cetacean Research CR3 hydrophones were deployed portside between 10-20 meters below the surface. The hydrophones CR3101 and CR3102 have measured sensitivities of -208.2db and -208.6dB, respectively. RBR solo depth loggers, with a stated accuracy of +/-0.05 percent full scale (about 1 cm water depth), were attached above the CR3 hydrophones to record depths.
  2. How accurate are the geographic locations?
    An Applanix POS-MV Elite (Position and Orientation System for Marine Vessels) was used to position the R/V Parke Snavely during data collection (https://www.applanix.com/downloads/products/specs/posmv/POS-MV-ELITE.pdf) has a stated positional accuracy of 0.5-2 meters squared. A Garmin GPSMAP 4212 (https://www.garmin.com/en-US/p/8114) with a stated accuracy within 5 to 10 meters. Accuracies of final products may be lower due to total propagated uncertainties of the mapping systems, which include position and motion compensation system, navigation, as well as data processing that includes calculating the source layback from the stern of the vessel (20 meters), and PyProj.Geod calculation of offset distance between the parker source position and the position of the receive hydrophone.
  3. How accurate are the heights or depths?
    Two-way travel time in milliseconds referenced to sea level is recorded in SEG-Y files. An RBR Solo-D depth logger was mounted above the CR3 receive hydrophones for most of the survey lines to estimate 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. states that they are accurate to +/- 0.05 percent of full scale (about 1 cm water depth). If this depth information was recorded, it is populated in the Receiver Group Elevation header (bytes 41-44).
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Some records do not include depth from the RBR logger due to instrument failure. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    Quality control was conducted during processing to ensure consistency of SEG-Y hydrophone receiver data recorded aboard the receiver vessel, and of depths logged by the RBR solo depth loggers. The position of the RVPS sparker source is recorded in SEG-Y header bytes 73/77 in decimal degrees. The position of the RVSL hydrophone receiver is recorded in SEG-Y header bytes 81/85 in decimal degrees.

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 USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - CMGDS
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov]
  2. What's the catalog number I need to order this data set? These SEG-Y data are available in the zip file 2021-619-FA_RVSL_RecSegy.zip that contains 36 standard SEG-Y format files of seismic shots with time stamp (Society of Exploration Geophysicists (SEG) Technical Standards, available for download at http://seg.org/Publications/SEG-Technical-Standards). SEG-Y files were named SL-LDDD-S-P_CR3###_Vp.segy where SL is the vessel ID (R/V San Lorenzo), LDDD is the Line depth site (meters), S is the Source instrument used (S for SIG-ELP790 sparker at 700J power, D10 for the Applied Acoustics Delta sparker at 1000J power, and D24 for the Applied Acoustics Delta sparker at 2400J power), P is the pass label (a, b, c, etc.), and CR3101 and CR3102 are the hydrophone model numbers. The 36 receiver SEG-Y files are contained in a single zip file 2021-619-FA_RVSL_RecSegy.zip in the Data Files section. A shapefile of the SEG-Y navigation is available in the zip file 2021-619-FA_RVSL_RecSegyNav_shapefile.zip. These navigation data are also contained in a single csv file (2021-619-FA_RVSL_RecSegyNav.csv).
  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 on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: Zip file contains the raw seismic data per navigation line in format SEG-Y (version SEG-Y rev 1) Size: 2900
      Network links: https://doi.org/10.5066/P9EHITBI
      Data format: Zip file contains the in format comma-delimited text (version RFC 4180) Size: 3.9
      Network links: https://doi.org/10.5066/P9EHITBI
      Data format: Zip file contains a shape file of R/V Parke Snavely source SEG-Y navigation trackline navigation points in csv format. in format shapefile (version ArcGIS Pro (version 2.4.1)) Size: 1.1
      Network links: https://doi.org/10.5066/P9EHITBI
    • Cost to order the data: None.

  5. What hardware or software do I need in order to use the data set?
    Use of SEG-Y data requires specialized software, such as ProMax and Seisworks by Landmark Geophysical; FOCUS and SeisX by Paradigm Geophysical; SPW by Parallel Geoscience; VISTA by Seismic Image Software; SeiSee by Dalmorneftegeophysica (DMNG); amongst others. CSV data can be viewed with any text editing or spreadsheet software. The cast location point shapefile can be viewed in any mapping software.

Who wrote the metadata?

Dates:
Last modified: 20-Sep-2022
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/CMGDS_DR_tool/DR_P9EHITBI/2021-619-FA_RVSL_RecSegy_metadata.faq.html>
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