Landslide evacuation zones offshore of Southern California, 2023

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Frequently anticipated questions:

What does this data set describe?

Title:
Landslide evacuation zones offshore of Southern California, 2023
Abstract:
Landslide evacuation zones, which represent the areas from which material is removed by landslide processes, have been mapped offshore of Southern California. Polygons were mapped from visual interpretation of high-resolution multibeam echosounder data (MBES) and single-beam echosounder data.
Supplemental_Information:
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
  1. How might this data set be cited?
    Papesh, Antoinette G., Walton, Maureen L., Conrad, James E., Brothers, Daniel S., Kluesner, Jared W., and McGann, Mary L., 20230821, Landslide evacuation zones offshore of Southern California, 2023: data release DOI:10.5066/P9IIWTYL, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    This is part of the following larger work.

    Papesh, Antoinette G., Walton, Maureen L., Conrad, James E., Brothers, Daniel S., Kluesner, Jared W., and McGann, Mary L., 2023, Digital maps of submarine landslides and mass wasting features offshore of southern California, 2023: data release DOI:10.5066/P9IIWTYL, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -120.773267
    East_Bounding_Coordinate: -117.311194
    North_Bounding_Coordinate: 34.518320
    South_Bounding_Coordinate: 32.425737
  3. What does it look like?
    evaczones_offshore_socal_2023_thumb.png (PNG)
    Southern California location map with bathymetry and mapped evacuation zones
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1998
    Ending_Date: 30-Jul-2021
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: polygon shapefile
  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):
      • GT-polygon composed of chains (63)
    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 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.
  7. How does the data set describe geographic features?
    evaczones_offshore_socal_2021
    polygons representing mapped landslide evacuation zones (Source: U.S. Geological Survey)
    FID
    internal feature number (Source: Esri) automatically generated sequential unique whole number identifier
    Shape
    feature geometry (Source: Esri) feature type
    name_id
    the name of the landslide evacuation zone (Source: U.S. Geological Survey and California Geological Survey) The names of the landslide evacuation zones are identical to the names of the landslide feature in which the evacuation zone belongs (see landslides_offshore_socal_2023.shp, available elsewhere in this data release). We define prefixes as follows: CB is Catalina Basin; CI is Catalina Island; GSC is Gulf of Santa Catalina; PA is Point Arguello; SBB is Santa Barbara Basin; SClB is San Clemente Basin; SCB is Santa Cruz Basin; SDT is San Diego Trough; SG is San Gabriel; SNB is San Nicolas Basin; SPB is San Pedro Basin.
    area_m2
    Area of landslide evacuation zone in square meters (Source: Esri)
    Range of values
    Minimum:5683
    Maximum:65654769
    Units:square meters
    Resolution:1
    area_err
    Estimated uncertainty of landslide evacuation zones from data resolution and user interpretation, values in square meters. GIS-calculated area was approximated as a circle geometry with radius uncertainty of plus or minus 50 meters and plus or minus 20 meters for areas greater and less than 100,000 square meters, respectively. These values are based on 2 pixels of the likely resolution of bathymetric data used for mapping (25-meter and 10-meter resolutions). The calculated error is the standard deviation of the maximum, minimum, and picked geometries. (Source: U.S. Geological Survey)
    Range of values
    Minimum:5394
    Maximum:1436185
    Units:square meters
    Resolution:1
    Entity_and_Attribute_Overview:
    Polygon shapefile containing outlines and attributes of landslide evacuation zones offshore of Southern California
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Antoinette G. Papesh
    • Maureen L. Walton
    • James E. Conrad
    • Daniel S. Brothers
    • Jared W. Kluesner
    • Mary L. McGann
  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?

These data were compiled as a part of a USGS effort to understand the geologic processes of mass wasting offshore of Southern California. They are intended to provide baseline knowledge of the geology, geomorphology, and distribution of landslide evacuation zones offshore of Southern California, for use by scientists, managers, and the general public. The data can be used with geographic information systems (GIS) software for research purposes.

How was the data set created?

  1. From what previous works were the data drawn?
    Dartnell and others, 2015 (source 1 of 5)
    Dartnell, Peter, Driscoll, Neal W., Brothers, Daniel S., Conrad, James E., Kluesner, Jared, Kent, Graham, and Andrews, Brian D., 2015, Colored shaded-relief bathymetry, acoustic backscatter, and selected perspective views of the inner continental borderland, southern California: Scientific Investigations Map DOI:10.3133/sim3324, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Digital Resource
    Source_Contribution:
    High resolution multibeam bathymetry was used as a base layer to begin drawing polygons for landslide interpretation. This source is a compilation of new and publicly available multibeam bathymetry data gridded at 25-meter resolution. Links to the data sources used are in the Data Catalog of the report.
    Dartnell and others, 2021 (source 2 of 5)
    Dartnell, Peter, Roland, Emily C., Raineault, Nicole A., Castillo, Christopher M., Conrad, James E., Kane, Renato, Brothers, Daniel S., Kluesner, Jared W., and Maureen A. L. Walton, 2021, Colored shaded-relief bathymetry, acoustic backscatter, and selected perspective views of the northern part of the California Continental Borderland, southern California: Scientific Investigations Map DOI:10.3133/sim3473, U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Digital resource
    Source_Contribution:
    High resolution multibeam bathymetry was used as a base layer to begin drawing polygons for landslide interpretation. This is a compilation of publicly available multibeam bathymetry data published at various resolutions ranging from 2-30 meters. Data sources used are shown on Figure 1 of the report and links to the data are provided therein.
    Seafloor Mapping Lab, 2018 (source 3 of 5)
    Seafloor Mapping Lab of California State University Monterey Bay, 2018, California Margin Geology Series: California State University, Monterey Bay, Seaside, CA.

    Online Links:

    Type_of_Source_Media: Digital resource
    Source_Contribution:
    High resolution multibeam bathymetry was used as a base layer to begin drawing polygons for landslide interpretation. High resolution multibeam bathymetry data at resolutions ranging from 2 – 10 meters from survey datasets H11875, H11876, H11877, H11878, H11879, H11880, H11881, H11882, H11883, H11891, H11950, H11951, H11952, H11953, and the 2014 Southern California Data Gap Project (Dana Point, San Onofre Blocks 01-03, La Jolla, Mission Beach, Point Loma North, Point Loma South, and Imperial Beach) were used.
    MBARI Seafloor Mapping Team, 2001 (source 4 of 5)
    Mapping, MBARI Seafloor Team, 2001, Santa Barbara multibeam survey: MBARI, online.

    Online Links:

    Type_of_Source_Media: Digital resource
    Source_Contribution:
    High resolution multibeam bathymetry was used as a base layer to begin drawing polygons for landslide interpretation. This is 20-meter resolution bathymetry data.
    National Geophysical Data Center, 2012 (source 5 of 5)
    NOAA, 2012, U.S. Coastal Relief Model - Southern California vers. 2: NOAA, online.

    Online Links:

    Type_of_Source_Media: Digital resource
    Source_Contribution:
    The NCEI 3-arc-second elevation grid (approximately 90-meter resolution) was used as a base layer to begin drawing polygons for landslide interpretation where no high resolution multibeam bathymetry data (listed above) were available.
  2. How were the data generated, processed, and modified?
    Date: 01-Feb-2023 (process 1 of 1)
    A compilation of existing bathymetry data was used as a base layer to map landslide features. Data from listed sources was downsampled in ESRI ArcMap and merged into a single 30-m grid to create the base layer. In some cases, the source swath data was higher resolution than the 30-m compilation and was used to map landslide features. A list of source swath data is detailed in the Source Used Citations. Where high (<30 m) resolution data was unavailable, the 90-m resolution NOAA Coastal Relief Model was used as the base layer. Using this base layer, landslides, headwall scarps, and areas of mass-wasting were mapped. Mapped landslide bodies were divided into evacuation zones and debris aprons based on negative (i.e., evacuation zones) or positive (i.e., debris aprons) seafloor relief associated with the landslide masses. Data sources used in this process:
    • Dartnell and others, 2015
    • Dartnell and others, 2021
    • Seafloor Mapping Lab, 2018
    • MBARI Seafloor Mapping Team, 2001
    • NOAA National Geophysical Data Center, 2012
  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?
    No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    These data and associated attributes have been created from several bathymetric datasets. Landslide evacuation zone mapping was cross-checked where more than one bathymetric dataset spanned a suspected landslide evacuation zone. The accuracy of evacuation zone mapping correlates to the highest resolution dataset that spans a particular evacuation zone.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract.
  5. How consistent are the relationships among the observations, including topology?
    No formal logical accuracy tests were conducted.

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.
  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? evaczones_offshore_socal_2023.zip contains the shapefile and associated files, and is accompanied by a browse image and CSDGM FGDC-compliant metadata.
  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?
    These data can be viewed with GIS software.

Who wrote the metadata?

Dates:
Last modified: 21-Aug-2023
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_P9IIWTYL/evaczones_offshore_socal_2023_metadata.faq.html>
Generated by mp version 2.9.51 on Fri Aug 25 11:46:23 2023