Chirp seismic profile images collected in 2016 by the U.S. Geological Survey off Town Neck Beach in Sandwich, Massachusetts, during field activity 2016-017-FA (PNG images)

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Frequently anticipated questions:

What does this data set describe?

Chirp seismic profile images collected in 2016 by the U.S. Geological Survey off Town Neck Beach in Sandwich, Massachusetts, during field activity 2016-017-FA (PNG images)
Geophysical and geological survey data were collected off Town Neck Beach in Sandwich, Massachusetts, in May and July 2016. Approximately 130 linear kilometers of subbottom (seismic-reflection) and 234-kilohertz interferometric sonar (bathymetric and backscatter) data were collected along with sediment samples, sea floor photographs, and (or) video at 26 sites within the geophysical survey area. Sediment grab samples were collected at 19 of the 26 sampling sites and video and (or) photographic imagery of the sea floor were taken at all 26 sites. These survey data are used to characterize the sea floor by identifying sediment-texture, seabed morphology, and underlying geologic structure and stratigraphy. Data collected during these 2016 surveys are included in this data release:
More information can be found on the websites for the Woods Hole Coastal and Marine Science Center field activities at and
Each profile image can be hotlinked to its corresponding trackline navigation contained within the Esri polyline shapefile '2016-017-FA_SeismicTracklines.shp'. Even 500-shot index markers along the top of the PNG images correlate to the positions of 500-shot intervals within the Esri point shapefile '2016-017-FA_SeismicShot500.shp'. The trackline and shotpoint shapefiles can be found online at
  1. How might this data set be cited?
    U.S. Geological Survey, 2019, Chirp seismic profile images collected in 2016 by the U.S. Geological Survey off Town Neck Beach in Sandwich, Massachusetts, during field activity 2016-017-FA (PNG images): data release DOI:10.5066/P9HZHXXV, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program, Woods Hole Coastal and Marine Science Center, Woods Hole, Massachusetts.

    Online Links:

    This is part of the following larger work.

    Ackerman, Seth D., Foster, David S., Danforth, William W., and Huntley, Emily C., 2019, High-resolution geophysical and sampling data collected off Town Neck Beach in Sandwich, Massachusetts, 2016: data release DOI:10.5066/P9HZHXXV, U.S. Geological Survey, Reston, VA.

    Online Links:

    Suggested citation: Ackerman S.D., Foster D.S., Danforth W.W., and Huntley, E.C., 2019, High-resolution geophysical and sampling data collected off Town Neck Beach in Sandwich, Massachusetts, 2016: U.S. Geological Survey data release,
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.494732
    East_Bounding_Coordinate: -70.456610
    North_Bounding_Coordinate: 41.786529
    South_Bounding_Coordinate: 41.761278
  3. What does it look like? (JPEG)
    Sample image of a PNG chirp seismic-reflection profile image offshore of Town Neck Beach in Sandwich, Massachusetts.
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 17-May-2016
    Ending_Date: 23-May-2016
    Ground condition of survey dates: 20160517-20160523. No geophysical data were collected on May 18 (JD 139), 21 (JD 142), and 22 (JD 143), 2016 ; see Completeness_Report for more information.
  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?
    PNG images of chirp seismic-reflection profiles (Source: U.S. Geological Survey)
    The PNG images can be hyperlinked to their polyline shapefile location in ArcGIS. The images show two-way travel time (seconds) on the y-axis and distance along profile (in 500-shot intervals) on the top x-axis.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

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?
    Seth Ackerman
    U.S. Geological Survey
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)

Why was the data set created?

PNG images of each chirp seismic profile were generated to integrate the seismic profiles into Geographic Information System (GIS) projects. The PNG images represent approximately 130 linear km of Knudsen chirp seismic-reflection data collected by the U.S. Geological Survey off Town Neck Beach in Sandwich, Massachusetts, in May 2016 during USGS field activity 2016-017-FA. These data can be used in conjunction with other geophysical and sample data to identify sea-floor morphology, sediment thickness and underlying structure and stratigraphy.

How was the data set created?

  1. From what previous works were the data drawn?
    Knudsen 3202 seismic data (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw seismic data.

    Type_of_Source_Media: disc
    Seismic-reflection data acquisition 2016-017-FA: Seismic profile data were collected using a Knudsen Engineering Limited (KEL) Chirp 3202 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 3202 system, digitally log trace data in the SEG-Y Revision 1 format (Norris and Faichney, 2002), and record DGPS navigation coordinates to the SEG-Y trace headers in arc seconds. The transducer draft was 0.5 m below the water surface, and the draft offset was accounted for during data acquisition. Navigation coordinates and water depths from the 200-kHz channel were logged together in ASCII formatted files for each survey line. Data were acquired at a peak frequency of 3.5 kHz, a 0.25-second fire interval, a 36-38 microsecond sample interval, and record lengths between 26 and 130 milliseconds. A total of 128 km of seismic data were collected. DGPS navigation was supplied by a Hemisphere receiver with the antenna mounted on the aft of the R/V Rafael's cabin just port of the centerline. Seismic-reflection data were processed using SIOSEIS (Henkart, 2011) and Seismic Unix (Cohen and Stockwell, 2011).
  2. How were the data generated, processed, and modified?
    Date: 2016 (process 1 of 5)
    SIOSEIS (version 2015.3.1) 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 SounderSuite sequentially over the duration of an acquisition session despite SEG-Y file changes, are preserved in the raw SEG-Y data. This process step and all subsequent process steps were performed by the same person - David Foster. Person who carried out this activity:
    David Foster
    U.S. Geological Survey
    384 Woods Hole Rd
    Woods Hole, MA

    508-548-8700 x2271 (voice)
    508-457-2310 (FAX)
    Date: 2016 (process 2 of 5)
    SIOSEIS was used to insert Kingdom Suite corrected sea-floor values into the SEG-Y trace headers, minimize the effect of sea surface heave using process 'swell', and write SEG-Y files for creation of browse images and digital interpretation.
    Date: 2016 (process 3 of 5)
    Seismic Unix (version 4.2) was used to read all processed 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 150 traces per inch. The profiles contain 80 milliseconds of two-way travel time within a 14-inch vertical window, yielding approximately 5.7 milliseconds per inch. Postscript images were converted to PNG format using ImageMagick (version 6.6.1). The x-axis units of the images are shot number while the y-axis is two-way travel time in seconds (note: extremely short lines may not display a complete x-axis in these images).
    Date: 07-Mar-2019 (process 4 of 5)
    A shell script was used to prepend the field activity identifier and the system name to the original seismic profile names. See Logical_Consistency_Report above for more information.
    Date: 07-Aug-2020 (process 5 of 5)
    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)
  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 2016-017-FA: Differential Global Positioning System (DGPS) navigation data were acquired with a Hemisphere DGPS receiver. Navigation data were sent to the Knudsen SounderSuite acquisition application, which logged the coordinates to individual trace headers in the Society of Exploration Geophysicists Y (SEG-Y) Revision 1 format (Norris and Faichney, 2002). A 2-m horizontal offset between the seismic transducers and the DGPS receiver was not accounted for during data acquisition, and resulting positional accuracy is assumed to be better than 10 m.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    There is a single image for every trackline. Time gaps occurred during this field activity on days when no survey data were collected due to bad weather, rough seas, and stops in surveying for equipment issues (on May 18, 21, and 22, 2016). Any sections of seismic data that were collected outside the survey area (such as short segments during the transit to or from the dock at the Sandwich Marina) were not processed and are therefore not included in this dataset.
  5. How consistent are the relationships among the observations, including topology?
    Processed seismic data were converted to PNG format for ease of seismic trace display. Quality control was conducted during processing. The original filenames for the PNG images are generally in the format l###f@_s.png where ### is the name of the trackline along which seismic data were collected, @ is the file iteration (a file iteration greater than 1 indicates that the survey line was split into multiple files during acquisition), and _s indicates that this is the swell-filtered seismic profile. An example of an iterated profile is survey line 38, which was interrupted 5 minutes into the line and then continued with recording to a new seismic file; therefore, there are two tracklines and seismic images for line 38: "l38f1_s.png" and "l38f2_s.png". The seismic profile images were renamed with the file-naming convention 2016017FA_Knudsen_l###f@_s.png, where 2016017FA_Knudsen_ is the field activity identifier followed by the sonar system name (Knudsen) and l###f@_s.png is the original filename. Note the LineName field in the trackline shapefile does not have the _s, but there is an ImageName field in the trackline shapefile that indicates the name of the associated swell-filtered (_s) PNG profile image. There is no data for what would be lines 8 and 41.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
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)
    U.S. Geological Survey-ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
  2. What's the catalog number I need to order this data set? USGS data release 2016-017-FA seismic profile images in PNG format from offshore of Town Neck Beach in Sandwich, Massachusetts, in May 2016 during USGS field activity 2016-017-FA. This dataset contains 62 PNG images and metadata files in 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?
    These data can be viewed with any PNG image viewing software. If the user has downloaded a zip file, it must be uncompressed in order to view the PNG images. The user must have software capable of uncompressing the zip file and displaying the PNG images. To use these images in conjunction with geospatial data (e.g., hotlinked to the seismic tracklines data in ArcGIS), a geospatial data viewer must be used.

Who wrote the metadata?

Last modified: 07-Aug-2020
Metadata author:
Seth Ackerman
U.S. Geological Survey
384 Woods Hole Rd.
Woods Hole, MA

508-548-8700 x2315 (voice)
508-457-2310 (FAX)
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

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