Quaternary Geology and Liquefaction Susceptibility, San Francisco, California 1:100,000 Quadrangle: A digital database

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Frequently anticipated questions:

What does this data set describe?

Quaternary Geology and Liquefaction Susceptibility, San Francisco, California 1:100,000 Quadrangle: A digital database
In this study, we develop a liquefaction susceptibility map of the San Francisco 1:100,000 quadrangle using Quaternary geologic mapping, historical liquefaction information, groundwater data, and previous studies.
  1. How might this data set be cited?
    Knudsen, Keith L., Noller, Jay S., Sowers, Janet M., and Lettis, William R., 1997, Quaternary Geology and Liquefaction Susceptibility, San Francisco, California 1:100,000 Quadrangle: A digital database: U.S. Geological Survey Open-File Report 97-715.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -123.0
    East_Bounding_Coordinate: -122.0
    North_Bounding_Coordinate: 38.0
    South_Bounding_Coordinate: 37.5
  3. What does it look like?
    http://pubs.usgs.gov/of/1997/of97-715/sf_plate1.pdf (PDF)
    PDF representation of quaternary geology map of San Francisco, Califonia
    http://pubs.usgs.gov/of/1997/of97-715/sf_plate2.pdf (PDF)
    PDF representation of liquefaction susceptibility map of San Francisco, Califonia
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1997
    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
      • Complete chain
      • GT-polygon composed of chains
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      UTM_Zone_Number: 10
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest unknown
      Ordinates (y-coordinates) are specified to the nearest unknown
      Planar coordinates are specified in meters
  7. How does the data set describe geographic features?
    Geologic map units (Source: OFR-97-715)
    Polygon type (Source: OFR-97-715)
    afArtificial fill
    QhcModern stream channel deposits
    QhbmHolocene bay mud
    QhsHolocene dune and beach sand
    QhbHolocene basin deposits
    QhtHolocene terrace deposits
    QhfHolocene alluvial fan deposits
    QhlHolocene alluvial fan levee deposits
    QhaHolocene alluvium, undifferentiated
    QfLate Pleistocene to Holocene fan deposits
    QaLate Pleistocene to Holocene alluvium, undifferentiated
    QpfLate Pleistocene alluvial fan deposits
    QpaLate Pleistocene alluvium, undifferentiated
    QpsLate Pleistocene dune sands
    QmtPleistocene marine terrace deposits
    QoaEarly or middle Pleistocene undifferentiated alluvial deposits
    brPre-Quaternary deposits and bedrock, undifferentiated
    Linear features on geologic map (Source: OFR-97-715)
    Line type (Source: OFR-97-715)
    contact, certainObserved contact
    contact, approx. locatedContact whose position is not precisely known
    contact, concealedConcealed contact whose position is inferred
    contact, inferredContact whose position is inferred
    fault, certainObserved fault
    fault, approx. locatedFault whose position is not precisely known
    fault, concealedConcealed fault whose position is inferred
    water boundaryBoundary of area of water
    map boundaryExtent of mapped area
    Geologic units at specific locations (same attributes as polygon coverage SF-GEOL.PAT) (Source: OFR-97-715)
    Historical liquefaction events (Source: OFR-97-715)
    Point type (Source: OFR-97-715)
    Ground SettlementPre-Loma Prieta Earthquake ground settlement
    Ground Settlement 1989Ground settlement during the Loma Prieta Earthquake
    Lateral SpreadingPre-Loma Prieta earthquake lateral spreading
    Lateral spreading 1989Lateral spreading during the Loma Prieta earthquake
    Sand boilsPre-Loma Prieta earthquake sand boil
    Sand boils and/or sand intrusionSand boils and/or sand intrusion during the Loma Prieta earthquake
    susceptibility of deposits to liquefaction as a function of groundwater depth within that deposit (Source: OFR-97-715)
    Liquefaction potential (Source: OFR-97-715)
    H2OArea of water
    vhvery high liquefactoin susceptibility
    hHigh liquefaction susceptibility
    mmoderate liquefaction susceptibility
    lLow liquefaction susceptibility
    vlVery low to none liquefaction susceptibility
    Linear features on liquefaction susceptibility map (same attributes as arc coverage SF-GEOL.AAT) (Source: OFR-97-715)
    Liquefaction susceptibility at specific location (same attributes as polygon coverage SF-LIQU.PAT) (Source: OFR-97-715)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Keith L. Knudsen
    • Jay S. Noller
    • Janet M. Sowers
    • William R. Lettis
  2. Who also contributed to the data set?
    Carl M. Wentworth, Todd T. Fitzgibbon, and Geoffrey A. Phelps graciously provided assistance with Alacarte and ARC/INFO. The scanning and editing of the digital maps was done by Scott E. Graham, Carolyn E. Randolph and Thomas E. May. Earl E. Brabb provided much helpful advice and feedback, as well as arranging for material support for the project.
  3. To whom should users address questions about the data?
    Keith L. Knudsen
    William Lettis & Associates, Inc.
    William Lettis & Associates, Inc., 1777 Botelho Dr., Suite 262
    Walnut Creek, CA

    (510) 256-6070 (voice)

Why was the data set created?

Earthquake-induced liquefaction has historically caused loss of life and damage to property and infrastructure. Observations of the effects of historical large-magnitude earthquakes show that the distribution of liquefaction phenomena is not random. Liquefaction is restricted to areas underlain by saturated, loose, cohesionless sand and silt. Areas susceptible to liquefaction can be delineated on the basis of geologic, geomorphic, and hydrologic mapping and map analyses (e.g., Youd and Perkins, 1987; Tinsley and Holzer, 1990; Sowers and others, 1995). Once liquefaction susceptibility zones are delineated, public agencies, private organizations, and individuals can prepare for and mitigate liquefaction hazards in these zones.
The study area includes the San Francisco Peninsula, the eastern San Francisco Bay area, and part of the northern San Francisco Bay area, including the cities of Burlingame, Concord, Oakland, Richmond, San Francisco, San Mateo, San Rafael, and Walnut Creek (Figure 1). Holocene estuarine deposits, Holocene stream deposits, Holocene eolian and beach deposits, and artificial fill are widely present in the region (Plate 1), and are typically the geologic materials most susceptible to liquefaction. Major faults capable of producing large earthquakes cross the study area, including the Concord, Hayward, San Andreas, and San Gregorio faults (Figure 1). These earthquakes expose the entire study area to long-duration ground motions with peak ground accelerations in excess of 0.2 g, sufficient to trigger liquefaction in highly susceptible natural deposits and artificial fill.

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 geologic map information was digitized from stable original of the geologic map at 1:100,000 scale. The author manuscripts (ink on greenline) were scanned using a Anatech monochrome scanner with a resolution of 800 dots per inch. The scanned images were vectorized and transformed from scanner coordinates to projection coordinates with digital tics placed by hand at map corners. The scanned lines were edited interactively by hand using ALACARTE, color boundaries were tagged as appropriate, and scanning artifacts visible at 1:100,000 were removed.
    Date: 01-Aug-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

    703-648-6974 (voice)
    703-648-6560 (FAX)
  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?
  5. How consistent are the relationships among the observations, including topology?
    This digital map database, compiled from previously unpublished data, and new mapping by the authors, represents the general distribution of surficial deposits in the San Francisco bay 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

    1-888-ASK-USGS (voice)
    1-303-202-4695 (FAX)
  2. What's the catalog number I need to order this data set? US Geological Survey Open-File Report 97-715
  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 "Quaternary Geology and Liquefaction Susceptibility, San Francisco, California 1:100,000 Quadrangle: A digital database," has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: Depositional contacts, faults, and unit labels, Liquefaction susceptibility, Historical liquefaction events, base maps in format ARCE (version 7.x) Size: 14
      Network links: http://pubs.usgs.gov/of/1997/of97-715/sf_data.tar.gz
    • Cost to order the data: none

Who wrote the metadata?

Last modified: 05-Feb-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

703-648-6533 (voice)
703-648-6252 (FAX)
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://geo-nsdi.er.usgs.gov/metadata/open-file/97-715/metadata.faq.html>
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