Chirp seismic-reflection profile data in JPEG image format Collected in the Indian River Bay, Delaware, on April 13, 2010, on U.S. Geological Survey Field Activity 2010-006-FA

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Frequently anticipated questions:


What does this data set describe?

Title:
Chirp seismic-reflection profile data in JPEG image format Collected in the Indian River Bay, Delaware, on April 13, 2010, on U.S. Geological Survey Field Activity 2010-006-FA
Abstract:
A geophysical survey to delineate the fresh-saline groundwater interface and associated sub-bottom sedimentary structures beneath Indian River Bay, Delaware, was carried out in April 2010. This included surveying at higher spatial resolution in the vicinity of a study site at Holts Landing, where intensive onshore and offshore studies were subsequently completed. The total length of continuous resistivity profiling (CRP) survey lines was 145 kilometers (km), with 36 km of chirp seismic lines surveyed around the perimeter of the bay. Medium-resolution CRP surveying was performed using a 50-meter streamer in a bay-wide grid. Results of the surveying and data inversion showed the presence of many buried paleochannels beneath Indian River Bay that generally extended perpendicular from the shoreline in areas of modern tributaries, tidal creeks, and marshes. An especially wide and deep paleochannel system was imaged in the southeastern part of the bay near White Creek. Many paleochannels also had high-resistivity anomalies corresponding to low-salinity groundwater plumes associated with them, likely due to the presence of fine-grained estuarine mud and peats in the channel fills that act as submarine confining units. Where present, these units allow plumes of low-salinity groundwater that was recharged onshore to move beyond the shoreline, creating a complex fresh-saline groundwater interface in the subsurface. The properties of this interface are important considerations in construction of accurate coastal groundwater flow models. These models are required to help predict how nutrient-rich groundwater, recharged in agricultural watersheds such as this one, makes its way into coastal bays and impacts surface water quality and estuarine ecosystems. For more information on the survey conducted for this project, see https://cmgds.marine.usgs.gov/fan_info.php?fan=2010-006-FA.
  1. How might this data set be cited?
    Bratton, John F., and Bergeron, Emile, 2014, Chirp seismic-reflection profile data in JPEG image format Collected in the Indian River Bay, Delaware, on April 13, 2010, on U.S. Geological Survey Field Activity 2010-006-FA: Open-File Report 2011-1039, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Cross, V.A., Bratton, J.F., Michael, H.A., Kroeger, K.D., Green, A., and Bergeron, E., 2014, Continuous Resistivity Profiling and Seismic-Reflection Data Collected in April 2010 from Indian River Bay, Delaware: Open-File Report 2011-1039, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -75.202086
    East_Bounding_Coordinate: -75.062936
    North_Bounding_Coordinate: 38.618986
    South_Bounding_Coordinate: 38.569244
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 13-Apr-2013
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
    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)
    • John F. Bratton
    • Emile Bergeron
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov

Why was the data set created?

The purpose of this dataset is to provide the seismic-reflection profile data in JPEG image format, which provides information about the sub-surface geology in the survey area.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2010 (process 1 of 6)
    The seismic acquisition system used on this cruise was an EdgeTech 424 Chirp sub-bottom system with a 4 to 24 kHz pulse bandwidth and a 2 ms pulse. The system towfish was attached by a short line to a cleat on a 2 x 6 board that was clamped across the bow of the boat. The towfish was on the starboard side of the boat, approximately 0.5 meters below the water surface. The acquisition software used to record the data was Discover 3100 version 7.01. The data were recorded in the SEG-Y data format IBM floating point with navigation supplied by the Lowrance GPS system. The navigation was recorded in the header of the seismic data in an arc second format. The record length is 133 ms, with a sample interval of 23 micro-seconds and 5788 samples per trace. The fire-rate was between 4 and 6 shots per second. The GPS antenna was located above the tow position of the seismic transducer.
    Date: May-2010 (process 2 of 6)
    The SEG-Y data were converted to Seismic Unix format using the following command:
    segyread tape=$1.sgy verbose=1 vblock=1000 conv=1 endian=0 | \
     segyclean  > $1.su
    
    This is a portion of a larger script used to extract the navigation from the SEG-Y headers. The script is initiated with a shell script so that every file with the "sgy" extension is read and converted to the SU format. Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • *.sgy
    Data sources produced in this process:
    • *.su
    Date: May-2010 (process 3 of 6)
    Another script executing Seismic Unix commands was run to convert the SU data file to a postscript file, and then in turn using an ImageMagick command to convert the postscript file to a JPEG. The command line example is:
    plotchirp 0 0.02 l4f1.001 7 98
    
    This runs the plotchirp script with the parameters of start time of trace 0, end time of trace 0.02 seconds, l4f1.001 is the seismic file, 7 refers to the plot height in inches, and 98 is the percent black clip (where higher is lighter). The plotchirp script is as follows:
    
    
    plotchirp:
    #! /bin/csh
    
    ## PLOTCHIRP
       echo "Process plotchirp usage:"
       echo "    plotchirp tmin tmax sufile hbox clip"
       echo "       tmin and tmax (seconds) to define the vertical plot window"
       echo "       ie, 0 0.25 (window 0 to 250 ms)"
       echo "       the SU input file excluding the .su extension"
       echo "       hbox is the vertical plot size in inches"
       echo "       enter the % black clip ie, 95 (higher is lighter)"
       echo " "
    
    # get number of traces to be used in plot scale
       echo "getting the total number of traces"
       set numtraces = `surange < $3.su | grep traces | awk ' {print($1)}' `
       echo "number of traces = "$numtraces
    # get ffid range for input
       echo "getting the range of FFID's"
    
       set ffidmin = `surange < $3.su | grep tracr | awk ' {print($2)}' `
       set ffidmax = `surange < $3.su | grep tracr | awk ' {print($3)}' `
    
      echo "The minimum FFID is "$ffidmin
      echo "The maximum FFID is "$ffidmax
      echo " "
      echo "Setting the sort order (data window), Set gain parameters"
    
     suwind key=tracr min=$ffidmin max=$ffidmax itmin=$1 tmin=$1 tmax=$2 verbose=0 < $3.su | \
      suchw key1=delrt a=0 | \
      suchw key1=tstat a=0 | suchw key1=muts a=0 | suchw key1=mute a=0 > $3.tmp
    
      echo "Set scaling for PS plot"
    # set the plot X size based on the number of traces/inch
      set wbox = `expr $numtraces / 40`
      echo "the plot length =" $wbox "inches"
      echo
    
    # set the plot Y size (hbox) in inches
      set tmin = $1
      echo "tmin ="$tmin
      set tmax = $2
      echo "tmax ="$tmax
      set hbox = $4
      echo "the plot height=" $hbox "inches"
    
    # PLOT POSTSCRIPT IMAGE
    # Change percentile for determining black clip value to adjust plot contrast
    # Higher bperc gives lighter plot - wclip=0 sets 0 and - amp. to white
    
     echo "Making the PostScript plot"
    
      supsimage wbox=$wbox hbox=$hbox \
      ybox=0.5 \
      x1beg=$1 x1end=$2 \
      d1num=0.01 d2num=500 \
      d2=1 \
      n1tic=10 n2tic=5 \
      bperc=$5 wclip=0 \
      grid1=dot grid2=dot \
      title="424 Chirp $3 SHOTS $ffidmin-$ffidmax" \
      label1="TWT [s]" label2="SHOT" \
     < $3.tmp > ../ps_files/$3.ps
    
    rm $3.tmp
    
    echo "Making jpeg"
    convert ../ps_files/$3.ps ../jpeg_files/$3.jpg
    
    # Save the processing runline history for future processing
    echo "plotchirp $1 $2 $3 $4 $5" >> Proc.log
    # Remove files not needed
    rm ../ps_files/*.ps
    
    Person who carried out this activity:
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@usgs.gov
    Data sources used in this process:
    • *.su
    Data sources produced in this process:
    • *.jpg
    Date: 02-Oct-2017 (process 4 of 6)
    Edits to the metadata were made to fix any errors that MP v 2.9.36 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). Attempted to modify http to https where appropriate. Moved the minimal source information provided to make it the first process step. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. 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: 20-Jul-2018 (process 5 of 6)
    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: 08-Sep-2020 (process 6 of 6)
    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?
    Jr., J.W. Stockwell, and Cohen, J.K., 2008, The New SU User's Manual (version 4.0): Center for Wave Phenomena - Colorado School of Mines, Golden, CO.

    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 navigation system used was a Lowrance 480M with an LGC-2000 Global Positioning System (GPS) antenna. The antenna was located above the seismic towfish tow point. The system towfish was attached by a short line to a cleat on a 2 x 6 board that was clamped across the bow of the boat. The towfish was on the starboard side of the boat, approximately 0.5 meters below the water surface.
  3. How accurate are the heights or depths?
    Although bathymetry was not recorded directly with this system, bathymetry can be derived by tracing the seafloor reflector in the seismic-reflection profiles. The seismic towfish was attached to a cleat by a short line on the starboard side of the boat. The transducer draft was approximately 0.5 m below the water surface. The draft offset was not included in the data acquisition.
  4. Where are the gaps in the data? What is missing?
    A JPEG format image is available for every seismic-reflection profile line collected on this cruise.
  5. How consistent are the relationships among the observations, including topology?
    Information not available in original metadata.

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:
The 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 originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA

    (508) 548-8700 x2251 (voice)
    (508) 457-2310 (FAX)
    vatnipp@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. What hardware or software do I need in order to use the data set?
    The user must have software capable of uncompressing the zip file. These files can then be viewed with any JPEG image viewing software.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
Woods Hole Coastal and Marine Science Center
Woods Hole, MA

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

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