Chirp seismic shotpoint navigation every 100 shots in geographic coordinates - Lake Mohave survey 2002

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Frequently-anticipated questions:

What does this data set describe?
    Title:
    Chirp seismic shotpoint navigation every 100 shots in geographic coordinates - Lake Mohave survey 2002
    Abstract:
    Lake Mohave is one of several multi-purpose reservoirs that have been constructed on the Colorado River. The lake was formed upon completion of the Davis Dam in 1953. No mapping of the floor of the lake had been conducted since completion of the Davis Dam. The U.S. Geological Survey, in cooperation with researchers form the University of Nevada Las Vegas, completed a geophysical survey of this lake in April 2002. The survey included collection of sidescan sonar imagery of nearly the entire lake floor, and high-resolution seismic-reflection profiles along widely spaced lines throughout the lake. The detailed mapping of the lake floor was used to determine the amount of sediment that had accumulated in the lake since impoundment, its distribution, and the processes of deposition.

  1. How should this data set be cited?

    Foster, David S. , and Cross, VeeAnn A. , 2005, Chirp seismic shotpoint navigation every 100 shots in geographic coordinates - Lake Mohave survey 2002:.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A. , Foster, David S. , and Twichell, David C. , 2005, Lake Mohave Geophysical Survey 2002: GIS Data Release: Open-File Report 2004-1247, U.S. Geological Survey, Woods Hole Science Center, Woods Hole, MA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -114.711617
    East_Bounding_Coordinate: -114.570700
    North_Bounding_Coordinate: 35.868300
    South_Bounding_Coordinate: 35.200633

  3. What does it look like?

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

    Beginning_Date: 18-Apr-2002
    Ending_Date: 28-Apr-2002
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

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

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • Entity point (5713)

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

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    seis100sht

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    LONGITUDE
    Longitude fix of the point. (Source: Software generated.)

    Range of values
    Minimum:-114.711617
    Maximum:-114.570700
    Units:decimal degrees

    LATITUDE
    Latitude fix of the point. (Source: Software generated.)

    Range of values
    Minimum:35.200633
    Maximum:35.868300
    Units:decimal degrees

    LINENUM
    Seismic line number associated with the shot point. (Source: Software generated.)

    Range of values
    Minimum:1
    Maximum:60

    SHOT
    Seismic shot point number associated with that navigational fix. (Source: Software generated.)

    Range of values
    Minimum:1
    Maximum:30353

    MONTH
    Month the data were acquired (referenced to UTC time). (Source: Scientist.)

    ValueDefinition
    4corresponds to April

    DAY
    Day of the month the data were acquired (referenced to UTC time). (Source: Scientist)

    Range of values
    Minimum:18
    Maximum:28

    YEAR
    Year the data were acquired. (Source: Scientist.)

    ValueDefinition
    2002year

    JDAY
    Julian day the data were acquired (referenced to UTC time). (Source: Scientist.)

    Range of values
    Minimum:108
    Maximum:118

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
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

Why was the data set created?
This shapefile is used to enable correlation between seismic-reflection profiles and the sidescan-sonar imagery, geologic interpretation, and other features represented on the lake floor.

How was the data set created?
  1. From what previous works were the data drawn?

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

    (process 1 of 5)
    This particular seismic data was acquired with a Knudsen chirp subbottom system with the data stored digitally on a laptop computer running the Knudsen system software. The navigation is stored in a separate file from the seismic SEG-Y data.

    Person who carried out this activity:

    David S. Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

    (process 2 of 5)
    The Knudsen system does not necessarily start each seismic file with shot 1. Since the SEG-Y data files were being processed so that each file started with shot 1, these navigation files needed to have the same correction. This way the shotpoint navigation will correspond to the plotted SEG-Y data.

    Person who carried out this activity:

    David S. Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

    (process 3 of 5)
    The shot point navigation for each line of seismic data was combined into a single file and then run through an AWK script which kept the first and last point of each line, and every shotpoint evenly divisible by 100.

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

    (process 4 of 5)
    The files were edited such that the day and julian day accurately represented the UTC timing of these events. In some cases, when the navigation system acquires data past midnight, the day and julian day were not updated.

    Person who carried out this activity:

    VeeAnn A. Cross
    U.S. Geological Survey
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

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

    (process 5 of 5)
    These points were then imported into ArcView and saved as a shapefile.

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?

  3. How accurate are the heights or depths?

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

  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 U.S. Geological Survey must be referenced as the originator of the dataset in any future products or research derived from these data.

  1. Who distributes the data set? (Distributor 1 of 1)

    David S. Foster
    U.S. Geological Survey
    Geologist
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2271 (voice)
    (508) 457-2310 (FAX)
    dfoster@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?

    These data were prepared by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Although all data published in this publication have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and/or the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials.

  4. How can I download or order the data?

Who wrote the metadata?
Dates:
Last modified: 29-Jun-2004

Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
384 Woods Hole Rd.
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 2.7.3 on Tue Jun 29 15:24:39 2004