Survey lines along which seismic reflection data were collected south of Martha's Vineyard and north of Nantucket by the U.S. Geological Survey offshore of Massachusetts in 2013 (2013-003-FA_512i_shottrack, Esri Polyline Shapefile, Geographic, WGS84)

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Frequently anticipated questions:

What does this data set describe?

Title:
Survey lines along which seismic reflection data were collected south of Martha's Vineyard and north of Nantucket by the U.S. Geological Survey offshore of Massachusetts in 2013 (2013-003-FA_512i_shottrack, Esri Polyline Shapefile, Geographic, WGS84)
Abstract:
These data were collected under a cooperative agreement between 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 5 to 30 meters (m) 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/). The geophysical data were collected during a survey in 2013 during USGS Field Activity 2013-003-FA (http://cmgds.marine.usgs.gov/fan_info.php?fa=2013-003-FA) and cover approximately 185 square kilometers of the inner continental shelf.
  1. How might this data set be cited?
    U.S. Geological Survey, 2016, Survey lines along which seismic reflection data were collected south of Martha's Vineyard and north of Nantucket by the U.S. Geological Survey offshore of Massachusetts in 2013 (2013-003-FA_512i_shottrack, Esri Polyline Shapefile, Geographic, WGS84): Open-File Report 2016-1168, 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.

    Ackerman, Seth D., Brothers, Laura L., Foster, David S., Andrews, Brian D., Baldwin, Wayne E., and Schwab, William C., 2016, High-Resolution Geophysical Data From the Inner Continental Shelf: South of Martha's Vineyard and North of Nantucket, Massachusetts: Open-File Report 2016-1168, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.805299
    East_Bounding_Coordinate: -70.034089
    North_Bounding_Coordinate: 41.389031
    South_Bounding_Coordinate: 41.195712
  3. What does it look like?
    http://pubs.usgs.gov/of/2016/1168/GIS_catalog/browse_img/big/2013-003-FA_512i_shottrack.jpg (JPEG)
    EdgeTech 512i trackline navigation offshore of Massachusetts south of Martha's Vineyard and north of Nantucket
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 22-May-2013
    Ending_Date: 11-Jun-2013
    Currentness_Reference:
    ground condition of survey dates: 20130522-20130611; see Completeness_Report for more information
  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):
      • String (272)
    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?
    2013-003-FA_512i_shottrack
    Trackline for seismic profiles (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 seismic data file (Source: U.S. Geological Survey) String up to 80 characters
    ImageName
    Name of seismic profile image used as hyperlink (Source: U.S. Geological Survey) String up to 80 characters
    Shot
    First shot number in seismic profile (Source: U.S. Geological Survey)
    Range of values
    Minimum:1
    Maximum:1
    Units:shot
    Resolution:1
    Shot_end
    Last shot number in seismic profile (Source: U.S. Geological Survey)
    Range of values
    Minimum:408
    Maximum:36800
    Units:shot
    Resolution:1
    Year
    Calendar year data were collected (Source: U.S. Geological Survey) String up to 80 characters
    DayUTC
    Start julian day and start time of day data were collected where Julian day is the integer number representing the interval of time in days since January 1 of the year of collection and time is in hours, minutes, and seconds. (Source: U.S. Geological Survey) String up to 80 characters
    DayUTC_end
    End julian day and end time of day data were collected where Julian day is the integer number representing the interval of time in days since January 1 of the year of collection. (Source: U.S. Geological Suvey) String up to 80 characters
    SurveyID
    WHCMSC field activity identifier in the new style (e.g. "2013-003-FA" where 2013 is the survey year, 003 is survey number of that year, and FA is Field Activity); Note the old style of this would be represented as "13003" (Source: USGS) String up to 80 characters
    VehicleID
    Name of the survey vessel used for data collection (Source: USGS) String up to 80 characters
    DeviceID
    Name of the sonar device used to collect seismic-reflection data (Source: USGS) String up to 80 characters
    Length_km
    Length of the seismic survey line in kilometers (UTM Zone 19N, WGS84) (Source: USGS)
    Range of values
    Minimum:0.26
    Maximum:22.33

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?
    David Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

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

Why was the data set created?

The seismic data associated with these navigation tracklines are used to define the sea-floor morphology as part of the Massachusetts Seafloor Mapping Project. This dataset contains trackline navigation for approximately 1920 km of EdgeTech SB-512i chirp seismic-reflection data collected by the U.S. Geological Survey during USGS survey 2013-003-FA in 2013 offshore of Massachusetts, south of Martha’s Vineyard and north of Nantucket. The seismic data associated with these navigation tracklines are used to define the sea-floor morphology as part of the Massachusetts Seafloor Mapping Project. (Esri Polyline Shapefile, Geographic, WGS84).

How was the data set created?

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

    Type_of_Source_Media: disc
    Source_Contribution:
    Seismic-reflection data acquisition 2013-003-FA: 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 M/V Scarlett Isabella of Cape May, NJ. Chesapeake Technologies' SonarWiz (v.5.03.0016) seismic acquisition software was used to control the Geo-Star topside unit, digitally log trace data 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). 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 100 ms (2170 samples/trace and .000046-s sample interval).
  2. How were the data generated, processed, and modified?
    Date: 2013 (process 1 of 7)
    SIOSEIS (version 2013.2) was used to read SEG-Y files, renumber shots starting from one, and write out new SEG-Y files. The original shot numbers, which were assigned by SonarWiz sequentially over the duration of an acquisition session despite SEG-Y file changes, are preserved in the raw SEG-Y data. In the same process, channel one (trace one, which is the envelope detected trace) within each shot was output. Channels two and three (raw data) were discarded. This process step and all subsequent process steps were performed by the same person - Wayne Baldwin. 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: 2013 (process 2 of 7)
    During the acquisition of lines 1 to 13, erroneous coordinates were intermittently recorded to the SEG-Y trace headers due to technical difficulties with the GPS system mounted on the catamaran vehicle. Scripts utilizing AWK (no version), Proj (version 4.6.0), and the Unix commands egrep, join, sort, and cat were used to replace coordinates in the text files created by the process described above with correct navigation from HYPACK raw files. The following steps were performed for each file: 1) navigation data were extracted from HYPACK raw files, creating a text file containing fields for Longitude, Latitude, and Julian day/UTC time (JD:HH:MM:SS); 2) records for the first and last shots, shots at multiples of 100, and the first record for each UTC second (files generally contain 4-5 shots per UTC second since the chirp shot rate is 4 Hz, while navigation update frequency is 1 Hz) were extracted from the original text files, and saved to new text files, only maintaining fields for LineName, ImageName, Shot, Year, and Julian day/UTC time (JD:HH:MM:SS); 3) files from the two previous steps were joined using the common field Julian day/UTC time (JD:HH:MM:SS); and 4) Geographic coordinates (WGS84) were converted to UTM zone 19 coordinates (WGS84) using Proj (version 4.6.0). The corrected navigation text files were substituted for the original data extracted from the SEG-Y trace headers. Beginning with Line 14, DGPS navigation was obtained from a Hemisphere receiver mounted on top, port side, forward end of the acquisition van. These coordinates were recorded in the SEG-Y source and receiver trace headers. Seismic Unix (version 4.2) was used to read renumbered SEG-Y files, write a Seismic Unix file, and extract SEG-Y trace header information, including shot number, longitude, latitude, year, Julian day, and time of day (UTC). Header information from each SEG-Y file was saved to text files containing records for the first and last shots, and all shots in between with unique navigation coordinates. Geographic coordinates (WGS84) were converted to UTM zone 19 coordinates (WGS84) using Proj (version 4.6.0).
    Date: 2016 (process 3 of 7)
    A Python script was used to apply layback to all corrected (lines 1 to 13) and original (beginning with line 14) seismic navigation. Layback positions, which account for the linear distance of 48 meters between the shipboard DGPS receiver and the towed catamaran vehicle, were calculated trigonometrically during post-processing. A moving median filter was applied to azimuths used in the layback correction. A Proj command was used to convert the layback-corrected positions back into Geographic coordinates and an AWK script was used to save all of the unique shot point navigation and shot point files containing the start and end shots and shots at an even 500 shot interval. A 500 shot interval was chosen because it corresponds to the annotation interval provided along the top of the seismic-reflection profile images. The unique and 500-shot files contain attributes for the corrected shot position in both UTM and Geographic coordinates, as well as the original uncorrected (pre-layback) positions in UTM, date, time and other survey information.
    Date: 2016 (process 4 of 7)
    Text files containing the layback-adjusted unique shot point positions for each seismic line were concatenated into a comma-delimited text file '2013-003-FA_512i_shotunique.csv', which is provided in the zip-compressed package of the 500-shot shapefile '2013-003-FA_512i_shot500.zip'. A Python script was used to import the CSV file into the SpatialLite (version 4.2.0_1) enabled SQLite (version 2.6) database. The geographic locations for each shot point were used to create point feature geometries in the SQL database. The point geometries were then used to create polyline geometries for each seismic trackline. An Esri polyline shapefile for the seismic tracklines was exported directly from the SQLite database using the Geospatial Data Library (GDAL 2.0.1) ogr2ogr executable with the Spatialite option and an SQL query.
    Date: 20-Jul-2018 (process 5 of 7)
    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
    Date: 18-Nov-2019 (process 6 of 7)
    Crossref DOI link was added as the first link in the metadata. 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
    Date: 08-Sep-2020 (process 7 of 7)
    Added keywords section with USGS persistent identifier as theme keyword. 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?
    Cohen, Jack, and Stockwell, John, 2011, CWP/SU: Seismic Un*x Release No. 4.2: Center for Wave Phenomena - Colorado School of Mines, Golden, CO.

    Online Links:

    Henkart, Paul, 2011, 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 Format 1: 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?
    Field activity 2013-003-FA: The SB-0512i was mounted on a catamaran sled and towed at the sea surface approximately 30 - 40 m astern of the M/V Scarlett Isabella. 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. Technical difficulties during portions of 2013-003-FA caused the GPS system mounted on the catamaran to malfunction, so DGPS navigation was obtained from a receiver mounted on top of the acquisition van. Layback positions, which account for the linear distance between the shipboard DGPS receiver and the towed catamaran vehicle, were calculated trigonometrically during post-processing. 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.
  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. There is no line L47f1 (acquisition system froze 2 minutes into this line, no good data were recorded), there is also no line L132 and L133. Time gaps occurred during this field activity where no surveying was done due to bad weather, rough seas and stops in port for crew changes. Planned surveying was paused and no main survey line data were collected during these times: 
    JD143 15:20 - JD146 20:06 (no data were collected on JD144 or JD145)
JD149 15:40 - JD151 18:59 (no data were collected on JD150)
JD153 00:01 - JD153 14:32
JD155 18:16 - JD156 02:06
JD158 06:12 - JD160 19:15 (no data were collected on JD159)
  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. Results of the layback calculation are erratic along some tracklines where the survey speed was slower than normal or changed significantly, as well as instances of sudden and/or drastic heading changes, and especially when the heading was nearly due south and the back bearing (reciprocal of the heading crosses back and forth across the 0 and 360 degree boundary (e.g. line MV_tie2). For users who wish, pre-layback corrected shot navigation is provide in the “Old_East” and “Old_North” attributes of the 500 shot shapefile as well as the '2013-003-FA_512ishotunique.csv' file (included in the zip file with the 500-shots shapefile) for all the unique shotpoint locations and the original non-layback positions. The navigation for lines L1-L13, which had to be taken from HYPACK navigation files due to the catamaran GPS technical difficulties described below, contain several fewer navigation fixes than shots that were recorded in the Seismic SEG-Y (and PNG images) because recording of the HYPACK navigation was stopped prior to stopping the seismic acquisition system. For the rest of the survey, the last shot point is reported to be 1 shot more than the range of shots shown in the seismic PNG image. This is due to a known glitch in the SIOSEIS software process ‘swell’, which erroneously causes the last two shots of the output SEGY file to be numbered the same.

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)
    Seth Ackerman
    U.S. Geological Survey, Woods Hole Science Center
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2315 (voice)
    sackerman@usgs.gov
  2. What's the catalog number I need to order this data set? USGS data release 2013-003-FA seismic trackline navigation from south of Martha's Vineyard and north of Nantucket. The zip file contains a shapefile and metadata files in three standard formats.
  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 Esri shapefile format. The zip file also contains associated metadata. The user must have software to read and process the data file. 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: 08-Sep-2020
Metadata author:
David Foster
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA
USA

508-548-8700 x2271 (voice)
508-457-2310 (FAX)
dfoster@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2016-1168/2013-003-FA_512i_shottrack_meta.faq.html>
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