JPEG formatted images of EdgeTech 512i chirp seismic-reflection profiles collected by the U.S. Geological Survey in the Cape Ann - Salisbury Beach, MA survey area.

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Frequently-anticipated questions:

What does this data set describe?

Title:
JPEG formatted images of EdgeTech 512i chirp seismic-reflection profiles collected by the U.S. Geological Survey in the Cape Ann - Salisbury Beach, MA survey area.
Abstract:
These data were collected under a cooperative agreement with the Massachusetts Office of Coastal Zone Management (CZM) and the U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Science Center. 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 reserves, 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 Cape Ann and Salisbury Beach Massachusetts project area. The data collected in two separate surveys in 2004 and 2005 and cover approximately 325 square kilometers of the inner continental shelf. High resolution bathymetry and backscatter intensity were collected in 2004 and 2005. Seismic profile data, sediment samples and bottom photography were also collected in 2005.
  1. How should this data set be cited?

    U.S. Geological Survey, 2008, JPEG formatted images of EdgeTech 512i chirp seismic-reflection profiles collected by the U.S. Geological Survey in the Cape Ann - Salisbury Beach, MA survey area.: USGS Open-File Report 2007-1373, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Barnhardt, Walter A. , Andrews, Brian D. , Ackerman, Seth D. , Baldwin, Wayne E. , and Hein, Christopher J. , 2008, 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, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -70.808261
    East_Bounding_Coordinate: -70.592854
    North_Bounding_Coordinate: 42.883553
    South_Bounding_Coordinate: 42.665094

  3. What does it look like?

    <https://pubs.usgs.gov/of/2007/1373/GIS/browse_jpg/SeismicReflection.jpg> (JPEG)
    JPEG image of a chirp seismic-reflection profile

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

    Beginning_Date: 08-Sep-2005
    Ending_Date: 20-Sep-2005
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: raster digital data

  6. How does the data set represent geographic features?

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

      This is a Raster data set. It contains the following raster data types:

      • Dimensions, type pixel

    2. What coordinate system is used to represent geographic features?

  7. How does the data set describe geographic features?

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?

    Brian Andrews
    U.S. Geological Survey
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    508-548-8700 x2348 (voice)
    (508) 457-2310 (FAX)
    bandrews@usgs.gov

Why was the data set created?

JPEG images of each seismic profile were generated in order to incorporate images of the seismic profiles into Geographic Information System (GIS) projects and data archives utilizing HTML. The JPEG images represent approximately 1100 km of Edgetech 512i chirp seismic-reflection profiles collected within the Cape Ann to Salisbury Beach survey area. Each profile image is hotlinked to its corresponding trackline navigation contained within an ESRI polyline feature class ('SeismicTrackLine' in the file geodatabase 'OFR2007_1373_gdb.zip') or shapefile ('SeismicTrackLine.zip'). Even 500 shot index markers along the top of the JPEG images correlate to the positions of 500 shot intervals within an ESRI point feature class ('SeismicShot_500' in the file geodatabase 'OFR2007_1373_gdb.zip') or shapefile ('SeismicShot_500.zip').

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 at sea (2005): Chirp seismic data were collected using an EdgeTech Geo-Star FSSB sub-bottom profiling system and an SB-0512i towfish (0.5-12 kHz) on the R/V Connecticut of Groton, CT. Delph Seismic+Plus acquisition software (Triton Elics International Inc.) was used to control the Geo-Star topside unit and digitally log trace data in the SEG-Y rev. 1 standard 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. Trace lengths were adjusted to account for changes in water depth, and consequently ranged between 100 and 200 ms. Tracklines are spaced between 100 and 1500 m apart in the shore parallel direction and about 1 km apart in the shore perpendicular direction.

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

    Date: 2007 (process 1 of 2)
    A script was run that used SIOSEIS (version 96.4) to shift all traces by -4 ms vertically to account for the position of the 512i towfish beneath the sea surface. A second SIOSEIS script was used to predict and remove sea surface heave, and mute water column portions of the traces by: 1)automatically picking the sea floor by identifying peak amplitudes within a vertical window; 2)smoothing sea floor picks using an along track filter approximating the period of sea surface heave (the filter window was set to use 46 traces); 3)creating a series of difference values between the raw and smoothed seafloor picks for each trace; 4)shifting traces up or down according to the difference values; and 5) muting each trace between time zero and the time of the smoothed sea floor pick, thus removing noise within the water column. Changes to the traces within each profile were saved to new "heave corrected" SEG-Y files, which were used for creation of JPEG browse images and digital interpretation.

    Person who carried out this activity:

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

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

    Date: 2007 (process 2 of 2)
    An AWK (no version) script was run that used Seismic Unix (version 4.1) to read the SEG-Y files and plot the data as 8-bit gray scale Postscript files using the Seismic Unix 'psimage' algorithm. All images were created with a horizontal scale of 200 traces per inch. Due to variable water depths and degrees of sub-surface penetration, images were plotted at three different vertical scales within a constant 8-inch vertical window. Most profiles contain 100 milliseconds of Two-Way Travel Time yielding 12.5 milliseconds per inch, while profiles in deeper water contain either 110 or 120 milliseconds, yielding 13.75 and 15 milliseconds per inch, respectively. Postscript images were converted to JPEG format using ImageMagick (version 5.5.6).

    Person who carried out this activity:

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

    (508) 548-8700x2226 (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:

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?

    The SB-0512i was towed approximately 10 m astern and approximately 3 m below the sea surface. RTK-GPS navigation was obtained from the receiver mounted above the interferometric sonar head, but seismic towfish layback was not accounted for. The layback of the towfish adds additional uncertainty due to changes in angle and scope of the tow cable in response to sea state and vessel speed. Based upon horizontal offsets between the fish and GPS receiver, GPS accuracies, and fish motion behind the vessel, the resulting positional accuracy is assumed to be ± 20 m.

  3. How accurate are the heights or depths?

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

    All acquired seismic data were processed and JPEG images produced.

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

    Processed seismic data were converted to JPEG format for ease of seismic trace display. Quality control was conducted 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)

    Brian Andrews
    U.S. Geological Survey, Woods Hole Science Center
    Geographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543
    USA

    508-548-8700 x2348 (voice)
    bandrews@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. Is there some other way to get the data?

    Digital copies of these chirp seismic data may also be obtained in the SEG-Y Rev. 1 standard format upon request. The data would be packaged on DVD, and contain the chirp-processed, envelope traces.

  6. What hardware or software do I need in order to use the data set?

    These data can be viewed with any image JPEG viewing software.

Who wrote the metadata?

Dates:
Last modified: 18-Dec-2008
Last Reviewed: 2008
Metadata author:
Brian Andrews
U.S. Geological Survey
Geographer
384 Woods Hole Rd.
Woods Hole, MA 02543-1598
USA

508-548-8700 x2348 (voice)
508-457-2310 (FAX)
bandrews@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 Mon Jan 26 14:14:56 2009