Chirp Seismic Survey Tracklines - Lake Mohave 2002

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set 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?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
• 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 data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

Title: Chirp Seismic Survey Tracklines - Lake Mohave 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 from 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 Survey Tracklines - Lake Mohave 2002:.

   Online Links:

   • <http://pubs.usgs.gov/of/2004/1247/data/nav/seislines.zip>

   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:

   • <http://pubs.usgs.gov/of/2004/1247>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -114.711633

   East_Bounding_Coordinate: -114.570683

   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):

      • String (57)

   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?

   seislines

   FID

   Internal feature number. (Source: ESRI)

   Sequential unique whole numbers that are automatically generated.

   Shape

   Feature geometry. (Source: ESRI)

   Coordinates defining the features.

   ID

   Sequential number for each separate polyline. (Source: Software generated.)

   Range of values
   Minimum:	0
   Maximum:	56

   LINENAME

   Number refering the the line number of data acquisition. (Source: Software generated.)

   Range of values
   Minimum:	1
   Maximum:	60

   HOTLINK

   String field indicating the location of the images to hotlink to each line. Has a variable for the initial part of the path. (Source: User defined.)

   character set.

   RANGE

   The Knudsen setting determining the fire rate of the seismic system. Recorded as a range in meters instead of time. (Source: Software defined.)

   Range of values
   Minimum:	50
   Maximum:	100
   Units:	meters

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • David S. Foster
   • VeeAnn A. Cross

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
   

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

1. From what previous works were the data drawn?

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

   (process 1 of 3)

   This particular navigation was recorded with a Knudsen chirp subbottom system. The Knudsen system stores the navigation in a file separate from the SEG-Y data. This file was reformatted using SED and AWK scripts to create a comma delimited file appropriate to be added to ArcView 3.2a as an event theme.

   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 2 of 3)

   This event theme was then converted to a polyline shapefile using an Avenue script that converts points to lines based on a unique line identifier within the attribute table.

   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 3 of 3)

   The attributes of JDAY and range (referring to the seismic range of the system) were added to the attribute table.

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?

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?

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:

• <http://www.esri.com/metadata/esriprof80.html>