SEG-Y Formatted Seismic-Reflection Profile Data Collected in the Potomac River/Chesapeake Bay from Sept. 6, 2006 to Sept. 8, 2006

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Frequently-anticipated questions:

What does this data set describe?

Title:
SEG-Y Formatted Seismic-Reflection Profile Data Collected in the Potomac River/Chesapeake Bay from Sept. 6, 2006 to Sept. 8, 2006
Abstract:
In order to test hypotheses about groundwater flow under and into Chesapeake Bay, geophysical surveys were conducted by U.S. Geological Survey (USGS) scientists on Chesapeake Bay and the Potomac River Estuary in September 2006. Chesapeake Bay resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge, which are contributing to eutrophication. The USGS has performed many related studies in recent years to provide managers with information necessary to make informed decisions about this issue. The research carried out as part of the study described here was designed to help refine nutrient budgets for Chesapeake Bay by characterizing submarine groundwater flow and discharge of groundwater beneath part of the mainstem and a major tributary, the Potomac River Estuary.
Supplemental_Information:
There are three online linkages. One links to the folder containing all the SEG-Y data files. The second linkage points to the WinZip file of the FGDC metadata for these SEG-Y data files. The third link is to the data catalog page which in turn has links to all of these files.
  1. How should this data set be cited?

    Bratton, John F. , Foster, David S. , and Cross, VeeAnn A. , 2010, SEG-Y Formatted Seismic-Reflection Profile Data Collected in the Potomac River/Chesapeake Bay from Sept. 6, 2006 to Sept. 8, 2006: Open-File Report 2009-1151, 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, VeeAnn A. , Foster, David S. , and Bratton, John F. , 2010, Continuous Resistivity Profiling and Seismic-Reflection Data Collected in 2006 from the Potomac River Estuary, Virginia and Maryland: Open-File Report 2009-1151, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -76.856667
    East_Bounding_Coordinate: -76.310249
    North_Bounding_Coordinate: 38.295665
    South_Bounding_Coordinate: 37.946077

  3. What does it look like?

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

    Beginning_Date: 06-Sep-2006
    Ending_Date: 08-Sep-2006
    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)

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    David S. Foster
    U.S. Geological Survey
    Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@usgs.gov

Why was the data set created?

To provide the digital seismic-reflection profile data in SEG-Y format which provides information about the sub-surface geology in the survey area as well as being able to be used in conjunction with the continuous resistivity profile (CRP) data.

How was the data set created?

  1. From what previous works were the data drawn?

    (source 1 of 1)
    Source_Contribution:
    The seismic acquisition system used on this cruise was a Knudsen Engineering Limited (KEL) 1600 USB system. The system has up to 1.2 kW power and is tuned to work with two Massa 3.5 kHz transducers. The transducers were mounted on an over-the-side mount on the port side of the ship. The transducer draft was 0.7 m below the water surface. This draft offset was not included in the data acquisition. The seismic data acquisition software was SounderSuite-USB Beta. This system failed to acquire navigation data from the DGPS NEMA string on the first two days (Julian day 149 and 150). The software was also not able to record data in SEG-Y standard format. KEL KEB format files were logged to disk. In addition, KEA ASCII files with shot (ping) numbers and times were saved to disk. Shot-point navigation was also absent in the KEA files on Julian days 149 and 150. On Julian day 151 a patched version of SounderSuite was received and installed. This version recorded navigation in the KEB and KEA files. SEG-Y recording was still not an option. A time server was used to synchronize the DGPS time on the KEL and HYPACK navigation systems. This was important as KEL SounderSuite records system time. Data were acquired at a 20 micro-second sample interval, 2048 samples for a 40 ms record length. Fire-rate was 0.20 seconds (or 5 shots per second). The KEL recording software was set up to automatically switch files at shot 20,000. Line 5 switched from file 0005_2006_249_2014_002.keb after shot 13509 to a new file (0005_2006_249_2014_003.keb) while changing display parameters, due to a bug in the acquisition software.

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

    Date: 2006 (process 1 of 3)
    KEB files were converted to match-filtered standard SEG-Y using KEL's PostSurvey version 1.56 software.

    Person who carried out this activity:

    David S. Foster
    U.S. Geological Survey
    Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@usgs.gov

    Date: 2006 (process 2 of 3)
    All KEB, KEA, and SEG-Y files were transferred to an external hard drive and transferred to a Mac OSX PowerBook for further processing. KEL match-filtered SEG-Y files were read and converted to the analytic form and then converted to instantaneous amplitude (envelope) SEG-Y using SIOSEIS 2006 seismic processing software. All SEG-Y output files were named the same as the original SEG-Y files, but placed in a separate folder.

    Person who carried out this activity:

    David S. Foster
    U.S. Geological Survey
    Geologist
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@usgs.gov

    Date: 2009 (process 3 of 3)
    The portion of line 5 that was split into two parts was renamed to coincide with the shot point navigation and tracklines shapefiles. This was necessary so that the order of the files reflects the direction of ship travel. Originally, based on the order of ship travel, the parts were part 2, part 1, part 4. Simply renaming part 1 to part 3 put the files in the proper order.

    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 02543-1598

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

    Data sources used in this process:
    • 0005_2006_249_2014_001.sgy

    Data sources produced in this process:

    • 0005_2006_249_2014_003.sgy

  3. What similar or related data should the user be aware of?

    Henkart, Paul, 2006, SIOSEIS: Scripps Institution of Oceanography, University of California - San Diego, LaJolla, CA.

    Online Links:

    Norris, Michael W. , and Faichney, Alan K. , 2002, SEG Y rev1 Data Exchange Format: 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?

    A differential global positioning system (DGPS) was used for the seismic-reflection data. This system was an Ashtech DGPS2 with the navigation being recorded by HYPACK navigation software. The offset from the seismic transducer to the DGPS antenna was 2 meters. This offset was not entered into the software.

  3. How accurate are the heights or depths?

    Although bathymetry was not recorded directly, bathymetry can be derived by tracing the seafloor reflector in the seismic-reflection profiles. The seismic transducers were mounted on an over the side mount on the port side of the ship. The transducer draft was 0.7 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 SEG-Y format data file is available for every seismic-reflection profile line collected on this cruise.

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

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)

    John F. Bratton
    U.S. Geological Survey
    Woods Hole Coastal and Marine Science Center
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2254 (voice)
    (508) 457-2310 (FAX)
    jbratton@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 data are available in the SEG-Y format. The user must have software capable of reading this format. Availability online links to a folder containing all the SEG-Y files, so a reasonably fast Internet connection will be necessary to download the files. The online linkage is to the folder containing the SEG-Y data. The maximum individual file is 164 MB. The WinZip file provides the FGDC metadata.

Who wrote the metadata?

Dates:
Last modified: 25-Mar-2010
Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
Woods Hole Coastal and Marine Science Center
Woods Hole, MA 02543-1598

(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)
Metadata extensions used:

Generated by mp version 2.9.6 on Thu Mar 25 13:51:48 2010