DH_SeismicShot_unique: Unique shot point navigation for EdgeTech SB-512i and SB-424 chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull.

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Frequently-anticipated questions:

What does this data set describe?

Title:
DH_SeismicShot_unique: Unique shot point navigation for EdgeTech SB-512i and SB-424 chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull.
Abstract:
These data were collected under a cooperative agreement with the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey (USGS), Coastal and Marine Geology Program, Woods Hole Science Center (WHSC). Initiated in 2003, the primary objective of this program is to develop regional geologic framework information for the management of coastal and marine resources. Accurate data and maps of sea-floor geology are important first steps toward protecting fish habitat, delineating marine resources, and assessing environmental changes due to natural or human impacts. The project is focused on the inshore waters (5-30 m deep) of Massachusetts between the New Hampshire border and Cape Cod Bay. Data collected for the mapping cooperative have been released in a series of USGS Open-File Reports (<http://woodshole.er.usgs.gov/project-pages/coastal_mass/html/current_map.html>). This spatial dataset is from the study area located between Duxbury and Hull Massachusetts, and consists of high-resolution geophysics (bathymetry, backscatter intensity, and seismic reflection) and ground validation (sediment samples, video tracklines and bottom photographs). The data were collected during four separate surveys conducted between 2003 and 2007 (NOAA survey H10993 in 2003, USGS-WHSC survey 06012 in 2006, and USGS-WHSC surveys 07001 and 07003 in 2007) and cover more than 200 square kilometers of the inner continental shelf.
  1. How should this data set be cited?

    U.S. Geological Survey, 2010, DH_SeismicShot_unique: Unique shot point navigation for EdgeTech SB-512i and SB-424 chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts between Duxbury and Hull.: Open-File Report 2009-1072, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Barnhardt, Walter A. , Ackerman, Seth D. , Andrews, Brian D. , and Baldwin, Wayne E. , 2010, Geophysical and Sampling Data from the Inner Continental Shelf: Duxbury to Hull, Massachusetts.: Open-File Report 2009-1072, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, Massachusetts.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -70.828283
    East_Bounding_Coordinate: -70.595687
    North_Bounding_Coordinate: 42.339977
    South_Bounding_Coordinate: 42.080213

  3. What does it look like?

    <https://pubs.usgs.gov/of/2009/1072/GIS/browse_jpg/big/DH_SeismicShot_unique.jpg> (JPEG)
    Unique shot point navigation for EdgeTech 512i and 424 seismic-reflection data collected offshore of Massachusetts between Duxbury and Hull

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 04-Aug-2006; 20070422
    Ending_Date: 20-Aug-2006; 20070502
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • Entity point (608047)

    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 D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.

  7. How does the data set describe geographic features?

    DH_SeismicShot_unique
    Unique shot point navigation for seismic profiles (Source: USGS)

    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 meters, WGS84 (Source: USGS)

    Range of values
    Minimum:349382.02
    Maximum:368187.87
    Units:meters
    Resolution:0.01

    NORTH
    Northing coordinate in UTM Zone 19 meters, WGS84 (Source: USGS)

    Range of values
    Minimum:4659922.68
    Maximum:4689141.38
    Units:meters
    Resolution:0.01

    LON
    Longitude coordinate in decimal degrees, WGS84 (Source: USGS)

    Range of values
    Minimum:-70.828283
    Maximum:-70.595687
    Units:Decimal degrees
    Resolution:0.000001

    LAT
    Latitude coordinate in decimal degrees, WGS84 (Source: USGS)

    Range of values
    Minimum:42.080213
    Maximum:42.339977
    Units:Decimal degrees
    Resolution:0.000001

    FILENAME
    Name of seismic data file (Source: USGS)

    Character string of width 50

    SHOTNUM
    Shot number (Source: USGS)

    Range of values
    Minimum:1
    Maximum:18270

    YEAR
    Calendar year data were collected (Source: USGS)

    Range of values
    Minimum:2006
    Maximum:2007

    JULDAY
    Julian day data were collected (Source: USGS)

    Range of values
    Minimum:112
    Maximum:232

    TIME
    Time of measurement in UTC (hh:mm:ss) (Source: USGS)

    Range of values
    Minimum:1
    Maximum:18270

    OLDEAST
    Pre-layback corrected easting coordinate in UTM, Zone 19 meters, WGS84 (attribute only included in DH_SeismicShot_unique.csv) (Source: USGS)

    Character string of width 20

    OLDNORTH
    Pre-layback corrected northing coordinate in UTM, Zone 19 meters, WGS84 (attribute only included in DH_SeismicShot_unique.csv) (Source: USGS)

    Character string of width 20

    SURVEYID
    WHSC field activity number (Source: USGS)

    Character string of width 10

    DEVICEID
    Sonar device used to collect seismic-reflection data (Source: USGS)

    Character string of width 15

    VEHICLEID
    Survey vessel name (Source: USGS)

    Character string of width 25

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Wayne Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598
    USA

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

Why was the data set created?

This dataset contains unique shot point navigation for approximately 1920 km of EdgeTech SB-512i and SB-424 chirp seismic-reflection data collected by the U.S. Geological Survey during two Woods Hole Science Center cruises (06012 and 07001) offshore of Massachusetts between Duxbury and Hull.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Source_Contribution:
    Seismic-reflection data acquisition 06012: Chirp seismic data were collected using an EdgeTech Geo-Star FSSB sub-bottom profiling system and an SB-0512i towfish (0.5-12 kHz), which was mounted on a catamaran and towed astern of the R/V Megan T. Miller of Port Jefferson, NY. EdgeTech J-Star seismic acquisition software was used to control the Geo-Star topside unit and digitally log trace data in the EdgeTech JSF format. Data were acquired using a 0.25-s shot rate, a 9-ms pulse length, and a 0.5 to 6 kHz frequency sweep. Recorded trace lengths were approximately 266 ms. Tracklines were spaced between 100 and 200 m apart in the shore parallel direction and between 1 and 3 km apart in the shore perpendicular direction. Seismic-reflection data acquisition 07001: Chirp seismic data were collected using an EdgeTech Geo-Star FSSB sub-bottom profiling system and an SB-424 towfish (4-24 kHz), which was mounted on a rigid pole on the starboard side of the R/V Rafael of Woods Hole, MA. EdgeTech J-Star and Triton Imaging Inc. SB-Logger seismic acquisition software was used to control the Geo-Star topside unit and digitally log trace data in EdgeTech JSF and SEG-Y Rev. 1 formats, respectively. Data were acquired using a 0.25-s shot rate, a 10-ms pulse length, and a 4 to 16 kHz frequency sweep. Recorded trace lengths were approximately 250 ms. Tracklines were spaced 100 m apart in the shore parallel direction and between 200 m and 2 km apart in the shore perpendicular direction.

  2. How were the data generated, processed, and modified?

    Date: Oct-2008 (process 1 of 4)
    'jsftosegy' (no version), a C script developed by Tom O'Brien (USGS - Woods Hole Seafloor Mapping Group) was used to convert raw chirp traces in the JSF format (acquired using EdgeTech J-Star software) to chirp-processed, envelope traces in the SEG-Y rev. 1 standard format.

    Person who carried out this activity:

    Wayne Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd
    Woods Hole, MA 02543-1598
    USA

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

    Date: Oct-2008 (process 2 of 4)
    A script was run that used Seismic Unix (version 4.1) to read the SEG-Y files, write a Seismic Unix file, and extract SEG-Y trace header information, which included shot number, longitude, latitude, year, Julian day, and time of day (UTC). Geographic coordinates (WGS84) were converted to UTM zone 19 coordinates (WGS84) using Proj (version 4.6.0). Before saving the header information to a text file, the data were filtered using AWK (no version) to save only unique shot point locations. For SB-424 data collected during field activity 07001, a separate text file containing even 500 shot intervals was saved. The 500 shot text file maintains the start and end shots, which may not necessarily be unique fixes. Due to the amount of spurious navigation fixes removed from SB-512i data collected during field activity 06012, a 500 shot text file was generated later (see shapefile DH_SeismicShot_500.shp) using the linear referencing tools contained in ArcGIS. A 500 shot interval was chosen because it corresponds to the annotation interval provided along the top of the seismic-reflection profile JPEG images, which are included in the '06012' and '07001' folders within 'GIS\hyperlink_images\seisimage'.

    Person who carried out this activity:

    Wayne Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd
    Woods Hole, MA 02543-1598
    USA

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

    Date: Oct-2008 (process 3 of 4)
    An AWK (no version) script was used to apply layback to seismic navigation acquired during portions of the 06012 survey when shipboard RTK-GPS was used in lieu of the non-operational GPS receiver mounted on the towed catamaran vehicle (This applies to files l25f2000 through l84f2000 acquired over Julian days 218 through 222. Attributes OLDEAST and OLDNORTH in the table for shapefile 'DH_SeismicShot_unique.shp', document pre-layback shot/trace positions). The script utilized a read-and-do loop to calculate and apply layback offsets to trace positions. During the initial loop through the script: 1) Easting and northing coordinates (UTM Zone 19, WGS84) for the first five traces of input navigation were read and easting and northing differentials between the consecutive positions were calculated; 2) The signs (+/-) of the differential values were compared to a look-up table to determine the appropriate conversion of the arc tangent (atan2(dy,dx)) angle between consecutive positions to a polar azimuth; 3) The average of the polar azimuths was calculated; 4) The sine and cosine of the average azimuth was calculated and multiplied by the linear distance between the catamaran and the shipboard RTK-GPS receiver, providing absolute values for easting and northing offsets, respectively; 5) A look-up table was used to determine the quadrant of the average azimuth and appropriately add or subtract the calculated offsets to the easting and northing coordinates of the first three input traces, producing final layback positions for those traces; 6) Layback and original easting and northing coordinates for the three adjusted traces were printed to a new layback navigation file that also retained additional attributes input records; and 7) Easting and northing coordinates of the fourth and fifth traces, the three azimuths computed between traces two, three, four, and five, and the average azimuth were held as input for calculations conducted in the subsequent loop. During subsequent loops through the script: 1) Easting and northing coordinates for three additional traces from input navigation were read, and easting and northing differentials were calculated between the consecutive positions, including the last trace position held from the previous loop; 2) Three new polar azimuths were calculated using the differential values, then a new average azimuth was calculated from the three that were held, the new three, and the average held from the previous loop (the previously calculated average was factored into the new average to smooth "kinks" along the layback navigation that can result from significantly different average azimuths calculated from one loop to the next); 3) New layback offset values were computed, and applied to the easting and northing coordinates of the last two traces input during the previous loop, and the fist trace input during the present loop. 4) Layback and original easting and northing coordinates for the three adjusted traces were appended to the layback navigation file started in the previous loop; and 5) Easting and northing coordinates of the second and third traces, the three new azimuths, and the average azimuth from the present loop were held as input for calculations conducted in the subsequent loop. Near the end of the input navigation file: 1) If less than three traces were present during a new loop, the layback offsets calculated during the previous loop were applied to remaining trace coordinates; 2) Layback and original easting and northing coordinates for the remaining adjusted traces were appended to the layback navigation file; and 3) The script reached its end, closed, and saved the layback navigation file. In this fashion, the script approximated a moving window, in which the average of six trace to trace azimuths was used to calculate layback offsets for three central trace positions. Exceptions were at the start of a file, where the first three input trace positions were adjusted using offsets calculated from the average of only four azimuths, and possibly at the end of a file, where remaining traces may have been adjusted using the offsets calculated during the previous loop.

    Person who carried out this activity:

    Wayne Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd
    Woods Hole, MA 02543-1598
    USA

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

    Date: Oct-2008 (process 4 of 4)
    Text files containing unique shot point positions for each seismic line (including the layback-adjusted SB-512i lines from field activity 06012) were concatenated into a comma-delimited text file ('DH_SeismicShot_unique.csv'), then imported into ArcMap (version 9.2) using 'Add XY data' and saved as points (Geographic, WGS84) in the ESRI shapefile format ('DH_SeismicShot_unique.shp'). Table attributes for the device used to collect the data ('DEVICEID'), survey vessel ('VEHICLEID'), and WHSC field activity number ('SURVEYID') were added and populated using the table editor in ArcMap (version 9.2).

    Person who carried out this activity:

    Wayne Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd
    Woods Hole, MA 02543-1598
    USA

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

  3. What similar or related data should the user be aware of?

    Stockwell, John, 2008, CWP/SU: Seismic Uni*x: Center for Wave Phenomena - Colorado School of Mines, Golden, CO.

    Online Links:

    Henkart, Paul, 2007, SIOSEIS: Scripps Institution of Oceanography, University of California - San Diego, LaJolla, CA.

    Online Links:

    Michael W. Norris and Alan K. Faichney, 2002, SEGY Rev.1 Data Exchange Format1: Society of Exploration Geophysicists, Tulsa, OK.

    Online Links:

    Barnhardt, Walter A. , Andrews, Brian D. , and Butman, Bradford, 2006, High-Resolution Mapping of the Inner Continental Shelf: Nahant to Gloucester, Massachusetts: Open-File Report 2005-1293, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Ackerman, Seth D. , Butman, Bradford, Barnhardt, Walter A. , Danforth, William W. , and Crocker, James M. , 2006, High-Resolution Geologic Mapping of the Inner Continental Shelf: Boston Harbor and Approaches, Massachusetts: Open-File Report 2006-1008, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

    Barnhardt, Walter A. , Andrews, Brian D. , Ackerman, Seth D. , Baldwin, Wayne E. , and Hein, Christopher J. , 2009, High-Resolution Geological Mapping of the Inner Continental Shelf: Cape Ann to Salisbury Beach, Massachusetts: Open-File Report 2007-1373, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

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

  1. How well have the observations been checked?

    All attributes were checked in a consistent manner.

  2. How accurate are the geographic locations?

    Field activity 06012: The SB-0512i was mounted on a catamaran sled and towed at the sea surface approximately 30 - 40 m astern of the R/V Megan T. Miller. Position data were provided by a Global Positioning System (GPS) navigation receiver mounted on the catamaran, and data were transmitted to the acquisition computer on the vessel via a 2.4 GHz radio link. During some portions of the survey, technical difficulties caused the GPS system mounted on the catamaran to malfunction. In these instances Real Time Kinematic (RTK) GPS navigation was obtained from a receiver mounted above the interferometric sonar head (This applies to files l25f2000 through l84f2000 acquired during Julian days 218 through 222). Layback positions, which account for the linear distance between the shipboard RTK-GPS receiver and the towed catamaran vehicle, were calculated trigonometrically during post-processing (see processing step 3). While the vehicle mounted GPS antenna was operational, positional accuracy is assumed to be ± 10 m. While the vehicle mounted GPS was not operational, positional accuracy is assumed to be ± 20 m; increased uncertainty arises because layback calculations do not account for fish motion behind the vessel, which is caused by sea state and vessel speed induced changes in the angle and scope of the tow cable.

    Field activity 07001: The SB-424 was mounted on a rigid pole, approximately 1 m below the sea surface on the starboard side of the R/V Rafael. Position data were provided by a RTK-GPS navigation receiver mounted directly above the interferometric sonar head. While the horizontal offset between the SB-424 and the RTK-GPS navigation receiver was not accounted for, this distance was less than 3 m, and the resulting positional accuracy is assumed to be ± 10 m.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Sections where navigation was recorded but no seismic data were logged are not included. Only the subsets of seismic-reflection data collected during field activities 06012 and 07001 that are within the study area between Duxbury and Hull have been included in this spatial dataset. Shot point data for approximately 945 km of additional seismic-reflection profiles collected south of Brant Rock, Massachusetts during these field activities will be published in a subsequent data release focused on Cape Cod Bay.

  5. How consistent are the relationships among the observations, including topology?

    Any spurious data points were removed 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 redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the source of this information.

  1. Who distributes the data set? (Distributor 1 of 1)

    Wayne Baldwin
    U.S. Geological Survey, Woods Hole Science Center
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543
    USA

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

  2. What's the catalog number I need to order this data set?

    Downloadable Data

  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?

    This zip file contains data available in Environmental Systems Research Institute (ESRI) point shapefile format. The user must have ArcGIS or ArcView 3.0 or greater software to read and process the data file. In lieu of ArcView or ArcGIS, the user may utilize another GIS application package capable of importing the data. A free data viewer, ArcExplorer, capable of displaying the data is available from ESRI at www.esri.com.

Who wrote the metadata?

Dates:
Last modified: 29-Oct-2009
Metadata author:
Wayne Baldwin
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA 02543-1598
USA

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

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.8.25 on Fri Feb 19 20:52:16 2010