San Francisco Bay region landslide folio part C - Summary distribution of slides and earth flows in the San Francisco Bay region, California

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Frequently anticipated questions:

What does this data set describe?

Title:
San Francisco Bay region landslide folio part C - Summary distribution of slides and earth flows in the San Francisco Bay region, California
Abstract:
The distribution of landslides evident in the landscape -- most of which are slumps, translational slides, and earth flows -- is of interest both for evaluation of hazard and risk and for use in further study of landslides. Future movement of such landslides is most likely to occur within and around the places where they have previously occurred. A map showing the generalized distribution of these landslides was published by Nilsen and Wright for the 9-county San Francisco Bay region in 1979. Original sources available at the time of that compilation were incomplete for the region. Landslide mapping that has since become available provides a basis for revision and extension of that work, and modern procedures allow this to be done in digital form.
  1. How might this data set be cited?
    Wentworth, C.M., Graham, S.E., Pike, R.J., Beukelman, G.S., Ramsey, D.W., and Barron, A.D., 1997, San Francisco Bay region landslide folio part C - Summary distribution of slides and earth flows in the San Francisco Bay region, California: U.S. Geological Survey Open-File Report 97-0745-C.

    Online Links:

    Other_Citation_Details:
    ARC/INFO vector Export format (11MB for entire region). Plotfiles in PostScript also available.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -123.678
    East_Bounding_Coordinate: -120.975
    North_Bounding_Coordinate: 38.888
    South_Bounding_Coordinate: 36.85
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1997
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: map
  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
      • GT-polygon composed of chains
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Planar coordinates are specified in meters
      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    SFBR-SEF.PAT
    Database for slides and earth flows (Source: OFR-97-0745-C)
    PTYPE
    Polygon type (Source: OFR-97-0745-C)
    ValueDefinition
    Few Landslidescontains few, if any, large mapped landslides, but locally contains scattered small landslides and questionably identified larger landslides
    Many Landslidesconsists of mapped landslides and more extensive intervening areas than in 'Mostly Landslide'; defined by excluding areas free of mapped landslides
    Mostly Landslideconsists of mapped landslides, intervening areas typically narrower than 1500 feet, and narrow borders around landslides
    Surficial depositsArea of suficial deposits
    very few landslidesLess landslide deposits than 'few landslide'
    waterareas of water
    unmappedunmapped area
    L-SCAN
    numerical value for landslide deposits (Source: OFR-97-0745-C)
    Range of values
    Minimum:1
    Maximum:8
    SFBR-SEF.PAT
    Specific location of slides and earth flows (same attributes as polygon coverage SFBR-SEF.PAT) (Source: OFR-97-0745-C)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • C.M. Wentworth
    • S.E. Graham
    • R.J. Pike
    • G.S. Beukelman
    • D.W. Ramsey
    • A.D. Barron
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Wentworth, Carl MJR
    USGS-GEO-WRG-EHZ
    Mail Stop 977, USGS
    345 Middlefield Rd
    Menlo Park, CA
    US

    650-329-4950 (voice)
    cwent@usgs.gov

Why was the data set created?

These maps and databases provide a summary of the distribution of landslides evident in the landscape of the San Francisco Bay region. Original identification and map delineation of these landslides required detailed analysis of the topography by skilled geologists, a task generally accomplished through the study of aerial photographs. Such original landslide maps are now available for most of the region at scales of 1:24,000 - 1:62,500 (Pike, 1997).

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 2)
    The three 1:125,000 map sheets of the region (Aitken, 1997) were compiled separately and then combined. County databases were clipped from the composite polygon coverage for the region. The generalized landslide zones of Nilsen and Wright (1979, category 5 of plates 1-3) were captured in digital form by scanning publication negatives. Vector perimeters of the resulting category 5 areas in the raster scans were determined automatically (GRIDPOLY) and processed to smooth the boundaries and eliminate polygons with areas less than 4000-5000 square meters (noise in the data). The revision lines in the northern part of the region were traced, scanned, hand-edited on-screen, registered with latitude/longitude intersections and intersections in the township/range network, and converted to closed polygons. The information for Santa Cruz County was prepared in the same fashion, using the original. The areas of surficial deposits were extracted from Wentworth (1997) by selecting appropriate polygons, putting them into a separate data layer, and then dissolving internal lines. The result was a vector polygon layer in which the polygons were categorized as unmapped (within outer sheet boundaries), water, surficial deposits, or bedrock.
    Date: 31-Jul-2000 (process 2 of 2)
    Creation of original metadata record Person who carried out this activity:
    Jennifer Lenz
    US Geological Survey
    12201 Surise Valley Drive, Mail Stop 918
    Reston, VA
    USA

    703-648-6974 (voice)
    703-648-6560 (FAX)
    pschweitzer@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?
  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?
    Complete
  5. How consistent are the relationships among the observations, including topology?
    These maps and databases provide a summary of the distribution of landslides evident in the landscape of the San Francisco Bay region. Original identification and map delineation of these landslides required detailed analysis of the topography by skilled geologists, a task generally accomplished through the study of aerial photographs. Such original landslide maps are now available for most of the region at scales of 1:24,000 - 1:62,500 (Pike, 1997). The summary map presented here makes selected use of these original maps and the 9-county compilation by Nilsen, Wright, and others (1979) to provide a basis for initial evaluation of areas vulnerable to slumps, translational slides, and earth flows in the region.

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: none
  1. Who distributes the data set? (Distributor 1 of 1)
    USGS Information Services
    Box 25286, Denver Federal Center
    Denver, Colorado
    USA

    1-888-ASK-USGS (voice)
    1-303-202-4695 (FAX)
    infoservices@usgs.gov
  2. What's the catalog number I need to order this data set? US Geological Survey Open-File Report 97-0745-C
  3. What legal disclaimers am I supposed to read?
    This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
    This database, identified as 'Summary Distribution of Slides and Earth Flows in the San Francisco Bay Region, California', has been approved for release and publication by the Director of the USGS. Although this database has been reviewed and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. This database is released on condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from it use.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 10-Jun-2016
Metadata author:
Peter N Schweitzer
USGS Midwest Area
Collection manager, USGS Geoscience Data Clearinghouse, http://geo-nsdi.er.usgs.gov/
Mail Stop 954
12201 Sunrise Valley Dr
Reston, VA
USA

703-648-6533 (voice)
703-648-6252 (FAX)
pschweitzer@usgs.gov
Metadata standard:
Content for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://geo-nsdi.er.usgs.gov/metadata/open-file/97-745/c/metadata.faq.html>
Generated by mp version 2.9.48 on Tue Jul 03 20:07:04 2018