Reprocessed multichannel seismic-reflection (MCS) data from USGS field activity T-1-96-SC collected in San Diego Bay, California in 1996

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Frequently anticipated questions:

What does this data set describe?

Title:
Reprocessed multichannel seismic-reflection (MCS) data from USGS field activity T-1-96-SC collected in San Diego Bay, California in 1996
Abstract:
This data release presents reprocessed multichannel seismic-reflection (MCS) data that was originally collected in 1996 in partnership with the California Division of Mines and Geology and Caltrans as part of a seismic hazard assessment of the Coronado Bridge in San Diego Bay, California. The original survey collected 130 km of data with a 14-cubic inch sleeve-gun (airgun) source, a 24-channel streamer, and 3.125 m shot spacing. Reprocessed profiles show increased data resolution, with data recorded to 750 ms two-way-travel-time, and interpretable data down to about 400 m.
Supplemental_Information:
Additional information about the field activities from which these data were derived is available online at:
http://cmgds.marine.usgs.gov/fan_info.php?fan=T196SC
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?
    Singleton, Drake M., Brothers, Daniel S., Kluesner, Jared W., and Sliter, Ray W., 20210518, Reprocessed multichannel seismic-reflection (MCS) data from USGS field activity T-1-96-SC collected in San Diego Bay, California in 1996: data release DOI:10.5066/P93Z2LYJ, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -117.230246
    East_Bounding_Coordinate: -117.097027
    North_Bounding_Coordinate: 32.728142
    South_Bounding_Coordinate: 32.631426
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/604fcb2cd34eb1203122e248?name=T-1-96-SC_SDBay_reproc_mcs_tracklines.jpg&allowOpen=true (JPEG)
    Map of tracklines along which MCS data were collected during USGS field activity T-1-96-SC
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 09-Jun-1996
    Ending_Date: 13-Jun-1996
    Currentness_Reference:
    ground condition at time data were collected.
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: 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 each seismic profile location are stored in the SEG-Y data trace headers in header bytes 81 and 85.
    2. What coordinate system is used to represent geographic features?
      The map projection used is WGS 1984 UTM Zone 11N.
      Projection parameters:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -117.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.0001
      Ordinates (y-coordinates) are specified to the nearest 0.0001
      Planar coordinates are specified in Meter
      The horizontal datum used is D WGS 1984.
      The ellipsoid used is WGS 1984.
      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: 0.5
      Depth_Distance_Units: two-way travel time
      Depth_Encoding_Method: attribute values
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview: 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)
    • Drake M. Singleton
    • Daniel S. Brothers
    • Jared W. Kluesner
    • Ray W. Sliter
  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: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

Data were reprocessed as part of an effort to investigate faulting in south San Diego Bay. Data were used to characterize fault structure, changes in sub-surface stratigraphy, and investigate recency of faulting. Reprocessing scheme included applying a linear moveout, f-k filter, velocity analysis, normal moveout, water bottom mute, stacking, and time migration. These data and information are intended for science researchers, students from elementary through college, policy makers, and general public.

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: 15-Jan-2021 (process 1 of 2)
    The original survey collected 130 km of MCS lines with a 14-cubic inch sleeve-gun (airgun) source, 24-channel streamer, and 3.125 m shot spacing. The original MCS data were stored as 12-fold common-depth-point gathers with 3.125 m bin spacing. Following transcribing of profiles to modern digital format, the originals SEG-Y files were reprocessed through the Shearwater Reveal software package. The original 24-trace shot gathers were sampled at 250 ms with a total length of 0.75 s. Linear moveout and f-k filters were applied to shot gathers to reduce linear coherent noise and energy from refracted arrivals at longer offsets, which were especially prevalent in shallow San Diego Bay and in portions of the bay proximal to large cement structures such as Naval docks. Next, shot gathers were sorted into common-mid-point (CMP) gathers using a 3.125-m bin spacing (12-fold). Velocity analysis was performed every 100 CMPs by maximizing semblance for supergathers constructed using 15 CMPs, and the resulting velocity models were used to apply normal moveout corrections (NMO). Following NMO corrections, water-bottom and stretch-mutes were applied, and the traces were stacked. Lastly, Stolt migration was applied to stacked sections using a constant velocity of 1600 m/s. Navigation is presented in UTM zone 11N in header bytes 73/77 and in 81/85.
    Date: 23-Aug-2021 (process 2 of 2)
    Corrected typo in DOI URL in onlink tag of metadata. No data were changed. (scochran@usgs.gov)
  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?
    The original survey lines and navigation from 1996 were stored on magnetic tape files that were destroyed in a warehouse fire. The reprocessed profiles in this dataset therefore did not include navigation data in the SEG-Y header. To overcome this, the original trackline map was georeferenced and individual profiles digitized. The total length of these profiles was divided by the 3.125 m gather spacing to produce the profile navigation. As a result of the georeferencing and uncertainty in profile locations on the original figure, the final locations of some profiles may carry a location error of ~10-100 m. Despite this uncertainty, a comparison of previously mapped features in San Diego Bay shows good agreement in the reprocessed MCS lines presented in this dataset.
  3. How accurate are the heights or depths?
    A formal accuracy assessment of the vertical positional information in the data set has not been conducted.
  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?
    No formal logical accuracy tests were conducted, but quality control was conducted during acquisition.

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, California Division of Mines and Geology, and Caltrans as the originator(s) of the dataset and in products derived from these data. This information is not intended for navigation purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? T-1-96-SC_SDBay_reproc_mcs.zip contains reprocessed sub-bottom (SEG-Y) data collected during USGS field activity T-1-96-SC. The data are divided up and presented by navigation line, as reflected in the individual file names.
  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?
  5. What hardware or software do I need in order to use the data set?
    Use of SEG-Y data requires specialized software, such as Reveal by Shearwater Geophysical; ProMax and Seisworks by Landmark Geophysical; FOCUS and SeisX by Paradigm Geophysical; SPW by Parallel Geoscience; VISTA by Seismic Image Software; SeiSee by Dalmorneftegeophysica (DMNG); amongst others.

Who wrote the metadata?

Dates:
Last modified: 23-Aug-2021
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/ScienceBase/DR_P93Z2LYJ/T-1-96-SC_SDBay_reproc_mcs_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:17:22 2021