PNG images of each chirp seismic profile collected in 2012 by the U.S. Geological Survey in the Connecticut River during field activity 2012-024-FA

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Frequently anticipated questions:


What does this data set describe?

Title:
PNG images of each chirp seismic profile collected in 2012 by the U.S. Geological Survey in the Connecticut River during field activity 2012-024-FA
Abstract:
A geophysical and geological survey was conducted at the mouth of the Connecticut River from Old Saybrook to Essex, Connecticut, in September 2012. Approximately 230 linear kilometers of digital Chirp subbottom (seismic-reflection) and 234-kilohertz interferometric sonar (bathymetric and backscatter) data were collected along with sediment samples, riverbed photographs, and (or) video at 88 sites within the geophysical survey area. Sediment grab samples were collected at 72 of the 88 sampling sites, video was acquired at 68 sites, and photographs of the river bottom were taken at 38 sites. These survey data are used to characterize the riverbed by identifying sediment-texture and riverbed morphology. More information can be found on the web page for the Woods Hole Coastal and Marine Science Center field activity: https://cmgds.marine.usgs.gov/fan_info.php?fan=2012-024-FA. Data collected during the 2012 survey can be obtained here: https://doi.org/10.5066/F7PG1Q7V.
Supplemental_Information:
Each profile image can be hotlinked to its corresponding trackline navigation contained within the Esri polyline shapefile '2012-024-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 '2012-024-FA_SeismicShot500.shp'.The trackline and shotpoint shapefiles can be found online at https://doi.org/10.5066/F7PG1Q7V
  1. How might this data set be cited?
    U.S. Geological Survey, 2016, PNG images of each chirp seismic profile collected in 2012 by the U.S. Geological Survey in the Connecticut River during field activity 2012-024-FA: data release DOI:10.5066/F7PG1Q7V, 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., Foster, David S., Moore, Eric M., Irwin, Barry J., Blackwood, Dann S., and Sherwood, Christopher R., 2017, High-Resolution Geophysical and Sampling Data Collected at the Mouth of the Connecticut River, Old Saybrook to Essex, Connecticut, 2012: data release DOI:10.5066/F7PG1Q7V, U.S. Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Ackerman S.D., Foster D.S., Moore E.M., Irwin B.J., Blackwood D.S., and Sherwood, C.R., 2017, High-resolution geophysical and sampling data collected at the mouth of the Connecticut River, Old Saybrook to Essex, Connecticut, 2012: U.S. Geological Survey data release, https://doi.org/10.5066/F7PG1Q7V.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -72.415081
    East_Bounding_Coordinate: -72.333670
    North_Bounding_Coordinate: 41.389389
    South_Bounding_Coordinate: 41.239720
  3. What does it look like?
    https://cmgds.marine.usgs.gov/data/field-activity-data/2012-024-FA/data/seismics/2012-024-FA_SeismicImages_browse.jpg (JPEG)
    Sample image of a PNG chirp seismic-reflection profile image
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 15-Sep-2012
    Ending_Date: 20-Sep-2012
    Currentness_Reference:
    ground condition of survey dates: 20120915-20120920; no sonar data were collected on 20120918; no seismic data were collected on 20120918 or 20120921; 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?
    2012-024-FA_SeismicImages
    PNG images of chirp seismic reflection profiles (Source: U.S. Geological Survey)
    Entity_and_Attribute_Overview:
    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
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov

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 and are used to define the river-bed morphology as part of a mapping project in the Connecticut River. The PNG images represent approximately 230 km of EdgeTech 424 chirp seismic-reflection data collected by the U.S. Geological Survey during USGS survey 2012-024-FA in the Connecticut River.

How was the data set created?

  1. From what previous works were the data drawn?
    SEG-Y 424 data (source 1 of 1)
    U.S. Geological Survey, Unpublished Material, raw seismic data.

    Type_of_Source_Media: disc
    Source_Contribution:
    Seismic-reflection data acquisition 2012-024-FA: Seismic profile data were collected using an EdgeTech 424 subbottom profiling system (frequency modulation swept frequency 4-24 kHz) which was towed from the starboard side of the R/V Rafael. Chesapeake Technologies' SonarWiz 5 acquisition software (version 5.05.0015) was used to control the EdgeTech 3100 portable topside unit, digitally log trace data in SEG-Y rev. 1 format (IEEE floating point), and record GPS navigation coordinates to the SEG-Y trace headers (in arcseconds of latitude and longitude, multiplied by a scalar of 100). During the survey, data were acquired using a 200 milliseconds (ms) shot rate with a 5 ms transit pulse length, logging 60 ms of data per trace. A swept frequency spectrum of 4-24 kHz was used for the entire survey, selectable via SonarWiz communicating with the EdgeTech 3100 topside controller. 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. Cable layback is 4 meters, depth below water line 0.5 meters. GPS offset from sheave: x=2.38m, y=0.62m, z=0. These values were entered into SonarWiz starting with line l8f2 (see note in horizontal position accuracy above). Seismic-reflection data were processed using SIOSEIS (2011) and Seismic Unix (Cohen and Stockwell, 2011).
  2. How were the data generated, processed, and modified?
    Date: Sep-2012 (process 1 of 5)
    SIOSEIS (version 2010.2.25) 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. This process step and all subsequent process steps were performed by the same person - Seth Ackerman, unless otherwise noted. Person who carried out this activity:
    Seth Ackerman
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA
    USA

    508-548-8700 x2315 (voice)
    508-457-2310 (FAX)
    sackerman@usgs.gov
    Date: Sep-2012 (process 2 of 5)
    The script Read424 (using 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). Geographic coordinates (WGS84) were converted to UTM zone 18 coordinates (WGS 84) using Proj (version 4.6.0). Header information from each SEG-Y file was saved to CSV text files after an AWK (no version) filter was used to maintain the first and last shots, shots at multiples of 500, and shots with unique navigation coordinates. End shots and shots at multiples of 500 may not have unique navigation coordinates. A 500 shot interval was chosen because it corresponds to the annotation interval provided along the top of the seismic-reflection profile PNG images. In the process of extracting the navigation from the SEG-Y files and saving it to the CSV files, a temporary plot is made to visually check the navigation fixes and identify if there are any issues or extreme outliers.
    Date: 22-Sep-2012 (process 3 of 5)
    As noted in the Logical Consistency and Completeness Reports above; there was an acquisition error where no navigation was being written to the SEGY header for survey lines L1-L16 for the EdgeTech 424 system. The navigation for lines L1-L16 were manually processed to create unique and 500-shot point CSV files similar to those that were generated by the Read424 script for the rest of the EdgeTech 424 survey data as described in the previous process step. Data from the Read424 process described above provided the time, shot number and line name for each survey line (L1-L16). Then a series of ad hoc AWK scripts and some manually editing was used to:
    1. parse and reformat the DEV 0 (Hemisphere DGPS) POS data messages from the HYPACK navigation files associated with L1-L16
    2. join the HYPACK navigation data with the output from the Read424 script for lines L1-L16
    3. convert the Easting/Northing coordinates to latitude/longitude (using Proj; version 4.6.0), reformat the data to match the other unique and 500-shot CSV files.
    As mentioned in the Completeness Report above, this extra step to correct the navigation data is important to creating the SeismicShot500 and SeismicTracklines files but does not affect these PNG files. Person who carried out this activity:
    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
    Date: Sep-2012 (process 4 of 5)
    The script Plot424 (using 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 100 traces per inch. The profiles contain 50 milliseconds of Two-Way Travel Time within an 14-inch vertical window, yielding approximately 3.6 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: 08-Sep-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)
    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 2012-024-FA: Although navigation is not stored in the images, positional accuracy is relevant to the accuracy of these data. The EdgeTech 424 subbottom profiling system was towed from a starboard-side davit on the R/V Rafael. The navigation for these data were acquired with an Hemisphere Differential Global Positioning System (DGPS) receiver and an antenna mounted on the aft of the R/V Rafael's cabin just port of the centerline. All DGPS data are referenced to WGS84. The SonarWiz 5 acquisition software (version 5.05.0015) logged the navigation coordinates (in arcseconds) to individual trace headers. Layback of 4 meters was accounted for in the acquisition software. The GPS offset to the sheave was x=2.38m, y=0.62m, z=0 but this offset was not set in the acquisition software for lines l1f1 thru l8f1. Beginning with l8f2 all offsets are accounted for in the acquisition software. See note in completeness report about the missing shots from the end of lines L1-L16 that account for, on average, 15 meters of missing navigation for those survey lines. For the remaining survey lines (and for the properly recorded navigation in lines L1-L16), based on previous similar survey parameters, the resulting positional accuracy of the seismic shotpoints is assumed to be better than 10 m; probably on the order of 3-5 meters.
  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 where no surveying was done due equipment problems (Tuesday 18Sept; JD262). On Friday 21Sept (JD265), the last day of the geophysical surveying, only the SWATHPlus sonar was run, no seismic data were collected. Due to the acquisition software error described above for lines L1-L16, the last several shot locations were not recoverable and therefore the shot point and tracklines datasets are truncated by the missing shots at the ends of L1-L16. The average number of missing shots in these 16 survey lines is 30 shots (min:5; max:100) which, at a survey speed of 5 knots, corresponds to approximately 15 meters that the tracklines/shot points may be cut short by (min:2.5m; max:51m). These PNG files are not affected by the missing shots, but that is the reason for any discrepancy between the number of shots noted on the PNG image and the number of shots noted in the tracklines and shot point datasets.
  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 filenames for the PNG images are generally in the format l###f@.png where ### is the name of the trackline along which seismic data was collected, @ is the file iteration (indicates the survey line was split into multiple files during acquisition). For example: survey line 8 was interrupted 5 minutes into the line, the survey vessel circled around to the location where surveying was paused; therefore are 2 tracklines and seismic images for line 8 "l8f1.png" and "l8f2.png". Due to the an acquisition software error where the GPS positions were not being written to the SEGY header, the navigation for lines L1-L16 had to be taken from HYPACK navigation files and inserted into the seismic SEG-Y files during post-processing. For each of these survey lines (L1-L16), the HYPACK navigation logging was stopped prior to stopping the seismic acquisition system and therefore the SEG-Y navigation contains several fewer navigation fixes than shots that were recorded in the seismic SEG-Y files (and consequently the resulting PNG images). The remaining lines (L17 and later) have the navigation properly acquired in the SEG-Y header.

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 2012-024-FA seismic profile images in PNG format from the Connecticut River. The zip file (2012-024-FA_SeismicImages.zip) contains 160 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. The zip files must be uncompressed in order to view the PNG images. The zip file also contains associated metadata. 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?

Dates:
Last modified: 08-Sep-2020
Metadata author:
Seth Ackerman
U.S. Geological Survey
Geologist
384 Woods Hole Rd.
Woods Hole, MA
USA

508-548-8700 x2315 (voice)
508-457-2310 (FAX)
sackerman@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/field_activities/2012_024_fa/2012-024-FA_SeismicImages.faq.html>
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