Shot point navigation at even 500 shot intervals for EdgeTech SB-512i, EdgeTech SB-424, and Knudsen 3200 chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts within northern Cape Cod Bay (CCB_SeismicShot_500 shapefile)

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Frequently anticipated questions:


What does this data set describe?

Title:
Shot point navigation at even 500 shot intervals for EdgeTech SB-512i, EdgeTech SB-424, and Knudsen 3200 chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts within northern Cape Cod Bay (CCB_SeismicShot_500 shapefile)
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 Coastal and Marine Science Center (WHCMSC). 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 of coastal Massachusetts, primarily in water depths of 3-30 meters deep. 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). The data collected in the study area located in northern Cape Cod Bay Massachusetts includes high-resolution geophysics (bathymetry, backscatter intensity, and seismic reflection), and ground validation (sediment samples, video tracklines, and bottom photographs). The data were collected during five separate surveys conducted between 2006 and 2008 and cover 480 square kilometers of the inner continental shelf. More information about the individual USGS surveys conducted as part of the northern Cape Cod Bay project can be found on the Woods Hole Coastal and Marine Science Center Field Activity webpage: 06012: http://quashnet.er.usgs.gov/data/2006/06012/ 07001: http://quashnet.er.usgs.gov/data/2007/07001/ 07002: http://quashnet.er.usgs.gov/data/2007/07002/ 07003: http://quashnet.er.usgs.gov/data/2007/07003/ 08002: http://quashnet.er.usgs.gov/data/2008/08002/
  1. How might this data set be cited?
    U.S. Geological Survey, 2010, Shot point navigation at even 500 shot intervals for EdgeTech SB-512i, EdgeTech SB-424, and Knudsen 3200 chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts within northern Cape Cod Bay (CCB_SeismicShot_500 shapefile): Open-File Report 2010-1006, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Andrews, Brian D., Ackerman, Seth D., Baldwin, Wayne E., and Barnhardt, Walter A., 2010, Geophysical and Sampling Data from the Inner Continental Shelf: Northern Cape Cod Bay, Massachusetts.: Open-File Report 2010-1006, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.643310
    East_Bounding_Coordinate: -70.112825
    North_Bounding_Coordinate: 42.093903
    South_Bounding_Coordinate: 41.929198
  3. What does it look like?
    http://pubs.usgs.gov/of/2010/1006/GIS/browse_jpg/CCB_SeismicShot_500.jpg (JPEG)
    Shot point navigation at even 500 shot intervals for EdgeTech 512i, EdgeTech 424, and Knudsen 3200 seismic-reflection data collected offshore of Massachusetts within northern Cape Cod Bay
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 16-Aug-2006
    Ending_Date: 07-May-2008
    Currentness_Reference:
    ground condition of four separate date ranges - 20060816 to 20060823; 20070429 to 20070503; 20070725 to 20070807; 20080429 to 20080507
  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 (10254)
    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?
    CCB_SeismicShot_500
    shot point navigation for seismic profiles (500 shot interval) (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:364049.89
    Maximum:407769.67
    Units:meters
    Resolution:0.01
    NORTH
    Northing coordinate in UTM Zone 19 meters, WGS84 (Source: USGS)
    Range of values
    Minimum:4643010.27
    Maximum:4661331.84
    Units:meters
    Resolution:0.01
    LON
    Longitude coordinate in decimal degrees, WGS84 (Source: USGS)
    Range of values
    Minimum:-70.64331
    Maximum:-70.112825
    Units:decimal degrees
    Resolution:0.000001
    LAT
    Latitude coordinate in decimal degrees, WGS84 (Source: USGS)
    Range of values
    Minimum:41.929198
    Maximum:42.093903
    Units:decimal degrees
    Resolution:0.000001
    FILENAME
    Name of seismic data file (Source: USGS) Character string of width 254
    SHOTNUM
    Shot number (first, last, and every 500 shot between) (Source: USGS)
    Range of values
    Minimum:1
    Maximum:25,016
    Units:shot number
    Resolution:1.0
    YEAR
    Calendar year data were collected (Source: USGS)
    Range of values
    Minimum:2006
    Maximum:2008
    Units:Calendar year
    Resolution:1
    JULDAY
    Julian day data were collected (Source: USGS)
    Range of values
    Minimum:119
    Maximum:235
    Units:Julian Day
    Resolution:1
    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)
    • U.S. Geological Survey
  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
    USA

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

Why was the data set created?

This dataset contains shot point navigation at even 500 hot intervals for approximately 3270 km of EdgeTech SB-512i, EdgeTech SB-424, and Knudsen 3200 chirp seismic-reflection data collected by the U.S. Geological Survey during four Woods Hole Science Center cruises (06012, 07001, 07002, and 08002) offshore of Massachusetts within northern Cape Cod Bay.

How was the data set created?

  1. From what previous works were the data drawn?
    Information unavailable from original metadata. (source 1 of 1)
    Information unavailable from original metadata. Assumed to be USGS., unknown, Information unavailable from original metadata..

    Other_Citation_Details:
    This file had a source contribution and time period of content. In order to pass the metadata harvester, the rest of the required source information fields were populated.
    Type_of_Source_Media: Information unavailable from original metadata.
    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. EdgeTech J-Star seismic acquisition software was used to control the Geo-Star topside unit, digitally log trace data in the EdgeTech JSF format, and record GPS navigation coordinates to the JSF trace headers. Data were acquired using a 0.27-s shot rate, a 9-ms pulse length, and a 0.5 to 6 kHz frequency sweep. Recorded trace lengths were approximately 266 ms. Northwest-southeast oriented tracklines were spaced between 100 and 200 m apart. 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 . EdgeTech J-Star and Triton Imaging Inc. SB-Logger seismic acquisition software was used to control the Geo-Star topside unit, digitally log trace data in EdgeTech JSF and SEG-Y Rev. 1 formats, respectively, and record GPS navigation coordinates to the JSF or SEG-Y trace headers. 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. Northwest-southeast oriented tracklines were spaced between 75 and 100 m apart. Seismic-reflection data acquisition 07002: 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, digitally log trace data in the EdgeTech JSF format, and record GPS navigation coordinates to the JSF trace headers. Data were acquired using a 0.25-s shot rate, a 5-ms pulse length, and a 0.5 to 8 kHz frequency sweep. Recorded trace lengths were approximately 250 ms. Northwest-southeast oriented tracklines were spaced between 100 m and 1 km apart, while northeast-southwest oriented tracklines were spaced between 1 and 3.5 km apart. Seismic-reflection data acquisition 08002: Chirp seismic data were collected using a dual frequency (3.5 and 200 kHz) Knudsen Engineering Limited Chirp 3200 system with transducers mounted on a rigid pole on the starboard side of the R/V Rafael of Woods Hole, MA. Knudsen SounderSuite seismic acquisition software was used to control the Chirp 3200 system, digitally log trace data in the SEG-Y Rev. 1 format, and record GPS navigation coordinates to the SEG-Y trace headers. Data were acquired using a 0.25 or 0.5-s shot rate, a 1 or 2-ms pulse length, and a peak frequency of 3.5 kHz. Recorded trace lengths were approximately 67 and 135 ms. Northwest-southeast oriented tracklines were spaced between 60 and 150 m apart.
  2. How were the data generated, processed, and modified?
    Date: Oct-2008 (process 1 of 9)
    '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
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Oct-2008 (process 2 of 9)
    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 data collected during field activities 07001, 07002, and 08002, separate text files containing even 500 shot intervals were saved. The 500 shot text files maintain the start and end shots for each survey line, 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 processing step 7) 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', '07001', '07002', and '08002' 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
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Oct-2008 (process 3 of 9)
    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 l199f2000 through l224f1000 acquired over Julian days 233 through 235. Attributes OLDEAST and OLDNORTH in the table 'CCB_SeismicShot_unique.csv', which is included as a separate file in the zip compressed version of the shapefile 'CCB_SeismicShot_500.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
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Oct-2008 (process 4 of 9)
    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 ('CCB_SeismicShot_unique.csv', which is provided in the zip-compressed package of the shapefile 'CCB_SeismicShot_500.shp'), then imported into ArcMap (version 9.2) using 'Add XY data' and saved as points (Geographic, WGS84) in the ESRI shapefile format. Person who carried out this activity:
    Wayne Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd
    Woods Hole, MA
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Oct-2008 (process 5 of 9)
    The shapefile containing unique shot point positions, created in the previous step, was used as an input for VACExtras (version 1.97), a VB collection of tools developed by VeeAnn Cross (USGS-WHSC), which converts point data to a new polyline shapefile ('CCB_SeismicTrackline.shp'), based on record order. The 'FILENAME' field was used to define which points were used to generate each polyline feature. Using XTools Pro (version 4.1.0) for ArcGIS desktop, the length of each polyline segment was calculated and included in the attribute field 'LENGTH', specifying UTM, Zone 19 N, WGS84, and kilometers. In addition, table attributes for the year ('YEAR') and Julian day ('JULDAY') of data collection, 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
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Oct-2008 (process 6 of 9)
    The records for SB-512i data collected during field activity 06012 were selected from the shapefile containing unique shot point positions ('CCB_SeismicShot_unique.csv', which is provided in the zip-compressed package of the shapefile 'CCB_SeismicShot_500.shp') and the polyline shapefile generated in the previous step ('CCB_SeismicTrackline.shp'); each was saved as a new temporary point and polyline shapefile, respectively. The new temporary shapefiles were then used as inputs for linear referencing tools in the ArcMap (version 9.2) toolbox to produce a new temporary shapefile containing even 500 shot intervals for the SB-512i navigation data collected during field activity 06012. This flow consisted of the following steps: 1) Routes were created from the polyline shapefile and calibrated with the point shapefile; 2) Start, end, and 500 shot interval hatch marks were created along the calibrated routes; 3) Hatchmarks were converted to graphics; 4) Graphics were converted to points and saved to a new shapefile using XTools Pro (version 4.1.0) for ArcGIS desktop ; 5) Point features in the new shapefile were located along the calibrated routes and the combined information was output as an event table; 6) Using the new event table, a route event layer was produced and converted to a new shapefile containing the even 500 shot interval points; and 7) The two-way table sort function in VACExtras (version 1.97) was used to sort the resulting shapefile by 'FILENAME' and ascending 'SHOTNUM' values. XTools Pro (version 4.1.0) for ArcGIS desktop was used to add and calculate 4 new fields in the shapefile containing even 500 shot intervals for the SB-512i data collected during field activity 06012. 'EAST' and 'NORTH' contain the UTM, Zone 19, WGS84, meters coordinates for the points, and 'LON' and 'LAT' contain their Geographic, WGS84, decimal degrees coordinates. In addition, table attributes for the year ('YEAR') and Julian day ('JULDAY') of data collection, 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
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: Oct-2008 (process 7 of 9)
    Text files containing even 500 shot interval point positions for data collected during field activities 07001, 07002, and 08002 were concatenated into a comma-delimited text files, then imported into ArcMap (version 9.2) and saved as points (Geographic, WGS84) in the ESRI shapefile format. Table attributes for the year ('YEAR') and Julian day ('JULDAY') of data collection, 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). Using the Merge function in the Data Management > General toolbox in ArcMap (version 9.2), shapefiles containing even 500 shot interval point positions for field activities 06012, 07001, 07002, and 08002 were merged together into the single shapefile 'CCB_SeismicShot_500.shp'. Person who carried out this activity:
    Wayne Baldwin
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd
    Woods Hole, MA
    USA

    508-548-8700 x2226 (voice)
    508-457-2310 (FAX)
    wbaldwin@usgs.gov
    Date: 20-Nov-2015 (process 8 of 9)
    Edits to the metadata were made to fix any errors that MP v 2.9.30 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). The format of the time period of content had to be fixed. This file had a source contribution and time period of content. In order to pass the metadata harvester, the rest of the required source information fields were populated. An online link to the data had to be fixed. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 9 of 9)
    USGS Thesaurus keywords added to the keyword section. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@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:

    Norris, Michael W., and Faichney, Alan K., 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, Reston, VA.

    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, Reston, VA.

    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, Reston, VA.

    Online Links:

    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, Reston, VA.

    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 activities 06012 and 07002: 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 field activity 06012, 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 l99f2000 through l224f1000 acquired during Julian days 233 through 235). 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 activities 07001 and 08002: The SB-424 towfish (07001) and Chirp 3200 transducers (08002) were mounted on a rigid pole, approximately 1 and 0.5 m, respectively, 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 horizontal offsets between the seismic-reflection sources and the RTK-GPS navigation receiver were not corrected in the sonar setup, this distance was less than 3 m, and the resulting positional accuracy during each field activity 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 of tracklines 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 northern Cape Cod Bay study have been included in this spatial dataset. Trackline navigation for approximately 1920 km of additional seismic-reflection profiles collected north of Brant Rock, Massachusetts during these field activities were published in USGS Open-File Report 2009-1072 Geophysical and Sampling Data from the Inner Continental Shelf: Duxbury to Hull, Massachusetts (http://pubs.usgs.gov/of/2009/1072/).
  5. How consistent are the relationships among the observations, including topology?
    Any spurious data points were removed during processing. For each seismic trackline there is one seismic-profile image that is hyperlinked by the field 'IMAGENAME'. No duplicates exist.

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
    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?
    • Availability in digital form:
      Data format: This WinZip file contains shot point navigation at even 500 shot intervals (CCB_SeismicSHot_500.shp) for EdgeTech SB-512i, EdgeTech SB-424, and Knudsen 3200 chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts within northern Cape Cod Bay. The WinZip file also contains a comma delimited file (CCB_SeismicShot_Unique.csv), that contains every unique shot point for the same surveys. in format SHP (version ArcGIS 9.2) ESRI point shapefile Size: 25.0
      Network links: http://pubs.usgs.gov/of/2010/1006/GIS/shapefile/CCB_SeismicShot_500.zip
      Media you can order: DVD-ROM (Density 4.75 Gbytes) (format UDF)
    • Cost to order the data: none

  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) shapefile format. The user must have software capable of uncompressing the WinZip file and displaying the shapefile. 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: 21-Jul-2018
Metadata author:
Wayne Baldwin
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA
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)

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