Chirp seismic-reflection data of field activity S-07-11-SC: offshore San Diego, and Los Angeles Counties, southern California from 2011-06-08 to 2011-06-22

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Frequently anticipated questions:


What does this data set describe?

Title:
Chirp seismic-reflection data of field activity S-07-11-SC: offshore San Diego, and Los Angeles Counties, southern California from 2011-06-08 to 2011-06-22
Abstract:
This dataset includes raw and processed, high-resolution seismic-reflection data collected in 2011 to collect information on active offshore faults. The survey area is offshore southern California between Long Beach and San Diego. The data were collected aboard the U.S. Geological Survey R/V Parke Snavely. The seismic-reflection data were acquired using an EdgeTech 512 subbottom profiler. Subbottom acoustic penetration spanned tens to about 50 meters, variable by location.
Supplemental_Information:
Additional information about the field activity from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=S0711SC Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Sliter, Ray W., Conrad, James E., Ryan, Holly F., and Triezenberg, Peter J., 2017, Chirp seismic-reflection data of field activity S-07-11-SC: offshore San Diego, and Los Angeles Counties, southern California from 2011-06-08 to 2011-06-22: data release DOI:10.5066/F7X63K3K, U.S. Geological Survey, Coastal and Marine Geology Program, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -118.45020
    East_Bounding_Coordinate: -117.33957
    North_Bounding_Coordinate: 33.54561
    South_Bounding_Coordinate: 32.92887
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 08-Jun-2011
    Ending_Date: 22-Jun-2011
    Currentness_Reference:
    ground condition at the time the data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: chirp seismic-reflection data in SEG-Y format
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference:
      Horizontal X and Y locations for the seismic profile locations are provided in ASCII position files and are stored in the SEG-Y data trace headers in the standard header locations.
    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 0.00001. Longitudes are given to the nearest 0.00001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_84.
      The ellipsoid used is WGS_84.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Local surface
      Depth_Resolution: 0.1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    Navigation and Seismic Shots with Time Stamp in standard SEG-Y file format
    Entity_and_Attribute_Detail_Citation:
    Society of Exploration Geophysicists (SEG) Technical Standards, available for download at http://seg.org/Publications/SEG-Technical-Standards

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Ray W. Sliter
    • James E. Conrad
    • Holly F. Ryan
    • Peter J. Triezenberg
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: Ray W. Sliter
    Geophysicist
    2885 Mission Street
    Santa Cruz, CA
    USA

    831-460-7427 (voice)
    831-427-4748 (FAX)
    rsliter@usgs.gov

Why was the data set created?

The U.S. Geological Survey (USGS) collected high-resolution seismic-reflection in June 2011, between Santa Catalina Island and Oceanside, southern California. The survey was designed to image faults and folds associated with movement on the numerous faults offshore southern California, including the Newport-Inglewood, Palos Verdes, San Pedro Basin, San Diego Trough, and several other unnamed fault zones. This data can be used to update the USGS Quaternary fault database and in shaking hazard models developed by the Working Group for California Earthquake probabilities. This work was funded by the USGS Coastal and Marine Catastrophic Hazards Project. Data were collected aboard the USGS R/V Parke Snavely simultaneously with a single-channel minisparker system [DOI:10.5066/F7SF2TCV]. About 204 km of data were collected using an EdgeTech Chirp 512. Subbottom acoustic penetration spanned tens to about 50 meters, variable by location. This dataset also includes navigation files of the surveyed transects. The images of bedrock, sediment deposits and tectonic structure provide geologic information that is essential to hazard assessment, regional sediment management and coastal and marine spatial planning at Federal, State and local levels, as well as to future research on the geomorphic, sedimentary, tectonic and climatic record of Southern California.

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: 2011 (process 1 of 2)
    Seismic-reflection data were collected using an Edgetech 512 Chirp subbottom profiling system consisting of a source transducer and an array of receiving hydrophones housed in a 500-lb “fish” towed at a depth of several meters below the sea surface. The swept-frequency “chirp” source signal is between 500 and 4,500 Hz, and data are recorded by hydrophones located on the bottom of the fish. At boat speeds of 4 to 4.5 nm/hour, seismic traces were collected roughly every 1 to 2 meters. The data consist of three-channels, a raw channel, a 90-degree phase-shifted channel and an “amplitude envelop” channel created and transformed internally from the other two channels. The data were recorded in standard SEG-Y 16-bit integer format with Triton Subbottom Logger (SBL) software that merges seismic-reflection data with differential GPS navigation data.
    Date: 2011 (process 2 of 2)
    The processed seismic-reflection SEG-Y files consist of the internally transformed amplitude envelope channel corrected for the depth of the fish below the sea surface using Paradigm Geophysical Echos seismic processing software (see: http://www.pdgm.com/products/echos/). 1) SEG-Y channel with sequence number “1” was written to a SEG-Y file; 2) The fish depth header word was read and converted from millimeters to two-way travel time to create a fish-depth static value; and 3) The fish depth static was applied to the data to correct for the vertical up and down movement of the Chirp fish and a final processed SEG-Y was output.
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Identified as best available version.
  2. How accurate are the geographic locations?
    Position data were provided by a Differential Global Positioning System (DGPS) navigation receiver. The Edgetech 512 Chirp fish was deployed 7m behind the DGPS receiver. Layback is estimated to be 7 ± 3m. No layback correction from the DGPS receiver position was applied to navigation data.
  3. How accurate are the heights or depths?
    Depths shown in the seismic data files are in milliseconds (round trip travel time) and are referenced to sea level. Vertical resolution is approximately 0.5 milliseconds and vertical accuracy is approximately ±4 milliseconds depending on sea state.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    Subbottom data were collected during USGS cruise S-07-11-SC using an Edgetech 512 Chirp subbottom profiling system consisting of a source transducer and an array of receiving hydrophones housed in a 500-lb “fish” towed at a depth of several meters below the sea surface. Quality control was conducted during the collection process.

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:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This information is not intended for navigational purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA
    USA

    1-831-460-7435 (voice)
  2. What's the catalog number I need to order this data set? namss.S-07-11-SC.scs.chirp.zip – this zip file contains raw and processed high-resolution seismic-reflection (SEG-Y) and navigation (ASCII) data collected during PCMSC field activity S-07-11-SC. The data are divided up and presented by navigation line, as reflected in the individual file name(s).
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 13-Mar-2017
Metadata author:
Ray W Sliter
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Geophysicist
2885 Mission Street
Santa Cruz, CA
USA

831-460-7427 (voice)
831-427-4748 (FAX)
rsliter@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/s0711sc_chirp_FGDC_metadata.faq.html>
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