2009-002-FA: <http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2009-002-FA>
2010-004-FA: <http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2010-004-FA>
2011-004-FA: <http://woodshole.er.usgs.gov/operations/ia/public_ds_info.php?fa=2011-004-FA>
U.S. Geological Survey, 2012, VS_SeismicShot_500: Shot point navigation at even 500 shot intervals for EdgeTech SB-512i chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts within Vineyard Sound by the U.S. Geological Survey in 2009, 2010, and 2011 (ESRI Point Shapefile, Geographic, WGS84).: Open-File Report 2012-1006, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.This is part of the following larger work.Online Links:
- <http://pubs.usgs.gov/of/2012/1006/GIS/shapefile/VS_SeismicShot_500.shp>
- <http://pubs.usgs.gov/of/2012/1006/appendix.html>
Andrews, Brian D. , Ackerman, Seth D. , Baldwin, Wayne E. , Foster, David S. , and Schwab, William C. , 2012, High-Resolution Geophysical Data From the Inner Continental Shelf at Vineyard Sound, Massachusetts.: Open-File Report 2012-1006, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.Online Links:
This is a Vector data set. It contains the following vector data types (SDTS terminology):
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.
Sequential unique whole numbers that are automatically generated.
Coordinates defining the features.
| Range of values | |
|---|---|
| Minimum: | 330352.74 |
| Maximum: | 380410.99 |
| Units: | meters |
| Resolution: | 0.01 |
| Range of values | |
|---|---|
| Minimum: | 4570466.21 |
| Maximum: | 4601005.71 |
| Units: | meters |
| Resolution: | 0.01 |
| Range of values | |
|---|---|
| Minimum: | -71.028392 |
| Maximum: | -70.431711 |
| Units: | decimal degrees |
| Resolution: | 0.000001 |
| Range of values | |
|---|---|
| Minimum: | 41.271214 |
| Maximum: | 41.548081 |
| Units: | decimal degrees |
| Resolution: | 0.000001 |
Character set.
Character set.
| Range of values | |
|---|---|
| Minimum: | 1 |
| Maximum: | 47443 |
| Units: | shot number |
| Resolution: | 1.0 |
| Range of values | |
|---|---|
| Minimum: | 2009 |
| Maximum: | 2011 |
| Units: | Calendar year |
| Resolution: | 1 year |
| Range of values | |
|---|---|
| Minimum: | 127 |
| Maximum: | 155 |
| Units: | Julian Day |
| Resolution: | 1 Julian Day |
Character set.
Character set.
Character set.
Character set.
508-548-8700 x2226 (voice)
508-457-2310 (FAX)
wbaldwin@usgs.gov
This dataset contains shot point navigation at even 500 shot intervals for 3800 km of EdgeTech SB-512i chirp seismic-reflection data collected by the U.S. Geological Survey during three Woods Hole Science Center cruises (2009-002-FA , 2010-004-FA, and 2011-004-FA) offshore of Massachusetts within Vineyard Sound.
Person who carried out this activity:
508-548-8700 x2226 (voice)
508-457-2310 (FAX)
wbaldwin@usgs.gov
Person who carried out this activity:
508-548-8700 x2226 (voice)
508-457-2310 (FAX)
wbaldwin@usgs.gov
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 DGPS receiver (31 or 37 m during 2010-004-FA and 51.5 m during 2011-004-FA), 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 first 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:
508-548-8700 x2226 (voice)
508-457-2310 (FAX)
wbaldwin@usgs.gov
Person who carried out this activity:
508-548-8700 x2226 (voice)
508-457-2310 (FAX)
wbaldwin@usgs.gov
Stockwell, John, 2011, CWP/SU: Seismic Uni*x: 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:
Michael W. Norris and Alan K. Faichney, 2002, SEGY Rev.1 Data Exchange Format1: Society of Exploration Geophysicists, Tulsa, OK.Online Links:
All attributes were checked in a consistent manner.
Field activity 2009-002-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 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. Positional accuracy is assumed to be ± 10 m. Field activity 2010-004-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 Megan T. Miller. 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 (see processing step 3). 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 2011-004-FA: The SB-0512i was mounted on a catamaran sled and towed at the sea surface approximately 50 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 2011-004-FA caused the GPS system mounted on the catamaran to malfunction, so DGPS navigation was obtained from a receiver mounted above the interferometric sonar head (This applies to all files acquired over Julian days 134-137). Layback positions, which account for the linear distance between the shipboard DGPS 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.
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 2009-002-FA, 2010-004-FA, and 2011-004-FA that are within the Vineyard Sound study are included in this spatial dataset. Trackline navigation for approximately 4500 km of additional seismic-reflection profiles collected within Buzzards Bay, Massachusetts during these field activities were published in USGS Open-File Report 2012-1002 High-Resolution Geophysical Data from the Inner Continental Shelf: Buzzards Bay, Massachusetts (<http://pubs.usgs.gov/of/2012/1002/>).
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.
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
508-548-8700 x2226 (voice)
wbaldwin@usgs.gov
Downloadable Data
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.
| Data format: | This WinZip file contains shot point navigation at even 500 shot intervals (VS_SeismicSHot_500.shp) for EdgeTech SB-512i chirp seismic-reflection data collected by the U.S. Geological Survey offshore of Massachusetts within Vineyard Sound and associated metadata. The WinZip file also contains a comma delimited file (VS_SeismicShot_Unique.csv), that contains every unique shot point for the same surveys. in format SHP (version ArcGIS 9.3) ESRI point shapefile Size: 40 MB |
|---|---|
| Network links: |
<http://pubs.usgs.gov/of/2012/1006/GIS/shapefile/VS_SeismicShot_500.zip> |
| Media you can order: |
DVD-ROM
(Density 4.75
Gbytes)
(format UDF)
|
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.
508-548-8700 x2226 (voice)
508-457-2310 (FAX)
wbaldwin@usgs.gov
