Map showing inventory and regional susceptibility for Holocene debris flows and related fast moving landslides in the conterminous United States: vector data

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Frequently anticipated questions:


What does this data set describe?

Title:
Map showing inventory and regional susceptibility for Holocene debris flows and related fast moving landslides in the conterminous United States: vector data
Abstract:
Debris flows, debris avalanches, mud flows and lahars are fast-moving landslides that occur in a wide variety of environments throughout the world. They are particularly dangerous to life and property because they move quickly, destroy objects in their paths, and can strike with little warning. The purpose of this map is to show where debris flows have occurred in the conterminous United States and where these slope movements might be expected in the future.
  1. How might this data set be cited?
    Brabb, E.E., Colgan, J.P., and Best, T.C., 1999, Map showing inventory and regional susceptibility for Holocene debris flows and related fast moving landslides in the conterminous United States: vector data: U.S. Geological Survey Miscellaneous Field Studies Map 2329, U.S. Geological Survey, Menlo Park, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -127.58938288
    East_Bounding_Coordinate: -69.47879091
    North_Bounding_Coordinate: 48.75581563
    South_Bounding_Coordinate: 31.800471
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 1928
    Ending_Date: 1999
    Currentness_Reference:
    All of the data on this map were compiled from reports published or field work conducted after the year 1928. No distinction was made between debris flow scars, made shortly after the events and debris flow deposits, which may be thousands of years old. We believe that all of the debris flows described in this report formed during the past 10,000 years (Holocene), but some of them could be older.
  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?
      The map projection used is Lambert Azimuthal Equal Area.
      Projection parameters:
      Longitude_of_Projection_Center: -100.00
      Latitude_of_Projection_Center: 45.00
      False_Easting: 0.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      Planar coordinates are specified in METERS
      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    USADFIX025L.PAT
    Point attributes in coverage USADFIX025L (points showing the locations of debris flows in the conterminous United States)
    STATE
    Two-letter USPS state code
    ValueDefinition
     
    REF
    The reference number(s) for a point or polygon, which refers to an entry in the bibliography for that state.
    Because multiple published and unpublished reports can refer to the same geographic area, a single point or polygon may contain many reference numbers. Multiple points or polygons may also contain the same reference number, since a single report may refer to multiple locations. Each points or polygon has a list of numbers, comma-delimited, with no spaces, that indicate every report in the bibliography which contains information for that location. (Source: USGS MF-2329)
    DFTYPE
    Subjective quality of point data
    ValueDefinition
    1Locations of debris flows and fast-moving landslides
    2Approximate location of debris flows and related fast-moving landslides
    3Identification as debris flow or related fast-moving landslide uncertain
    4Approximate location, and uncertain identification as debris flow or related fast-moving landslide
    5Location of debris flow or related fast-moving landslide specific only by county
    6Identification as debris flow or related fast-moving landslide uncertain and specific only by county
    7Location of debris flow or or related fast-moving landslide from unpublished report
    8Approximate location and uncertain identification as debris flow or related fast-moving landslide
    USADFIP025L.PAT
    Polygon attributes in coverage USADFIP025L (polygons showing the locations of debris flows in the conterminous United States) (Source: USGS MF-2329)
    STATE
    Two-letter USPS state code (Source: USGS MF-2329)
    REF
    The reference number(s) for a point or polygon, which refers to an entry in the bibliography for that state.
    Because multiple published and unpublished reports can refer to the same geographic area, a single point or polygon may contain many reference numbers. Multiple points or polygons may also contain the same reference number, since a single report may refer to multiple locations. Each points or polygon has a list of numbers, comma-delimited, with no spaces, that indicate every report in the bibliography which contains information for that location. (Source: USGS MF-2329)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Brabb, E.E.
    • Colgan, J.P.
    • Best, T.C.
  2. Who also contributed to the data set?
    We are grateful to several state geologists and members of their staff who kindly reviewed a preliminary copy of the map and the bibliography and provided new information. We are particularly grateful to M. Lee Allison, State Geologist for Utah, and members of his staff who contributed a digital database of debris flow locations for Utah. We also wish to thank Stephen Ellen, Russell Campbell, Gerald Wieczorek, and David Howell for their reviews and help during various phases of the work.
  3. To whom should users address questions about the data?
    Steve Kambly
    U.S. Geological Survey
    561 National Center
    Reston, VA

    703-648-5094 (voice)
    skambly@usgs.gov

Why was the data set created?

These data are intended for geographic display and analysis at the national level, and for large regional areas. It is not intended for hazard evaluation or other site-specific work, and should not be used for such. It can be used to determine where debris flow processes may be a problem and where additional information and investigation are warranted. Although the digital form of the data removes the constraint imposed by the scale of a paper map, the detail and accuracy inherent in map scale are also present in the digital data. The fact that this database was edited at a scale of 1:2,500,000 means that higher resolution information is not present in the data. Plotting at scales larger than 1:2,500,000 will not yield greater real detail, and it may reveal fine-scale irregularities below the intended resolution of the database. Similarly, where this database is used in combination with other data of higher resolution, the resolution of the combined output will be limited by the lower resolution of these data. No responsibility is assumed by the U.S. Geological Survey in the use of these data.

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: 1984 (process 1 of 4)
    Best and Brabb prepared an inventory of past debris flows in 1984 using data from the reconnaissance field investigations and published and unpublished reports, a list of which was eventually published by Alger and Brabb (1985). This information was plotted on 1:500,000-scale USGS state maps and transferred by hand to a 1:2,500,000-scale greenline base map of the United States.
    Date: 1997 (process 2 of 4)
    In 1997, this greenline base map was scanned and registered by A. Barron and M. Sinor. The registered map was edited and digitized using ARC/INFO, and the REF database field was completed. No new information was added to the map at that time. Data sources produced in this process:
    • dfiply3
    • dfipoints2
    Date: 1999 (process 3 of 4)
    In 1998 and 1999, new information was added to bring the map up-to-date. The data were gathered from published and unpublished reports of debris flows primarily covering the years 1984 -1999. A few older reports were included that had been overlooked in the original map. In addition, all state geologists were contacted to find out if they had information on debris flows. Several state geologists and members of their staff provided significant new information.
    If a report included a map at a scale larger than that of the compilation (1:2,500,000), the map or a photocopy was scanned. Other reports contained only the names of places where debris flows had occurred, or a map at a scale smaller than 1:2,500,000, or a map with no geographic coordinates. In those cases, the debris flows were located on the appropriate 1:500,000-scale USGS state map or a 1:100,000-scale USGS topographic map and plotted by hand on a Mylar overlay. This overlay was then scanned.
    The scanning was done at 400 dpi on either a UMAX color flatbed scanner or a Contex FSC-8000dsp color scanner, depending on the size of the map or tracing. The scanned images were transformed from scanner coordinates to geographic coordinates in ARC/INFO with digital tics placed by hand. The scanned lines and/or points were edited interactively using ALACARTE (Wentworth and Fitzgibbon 1991), and the database fields (Tables 3 and 4) were filled in as appropriate. In addition, a new database field (table 5) was added to store the name of the state under which the report for a feature on the map was referenced. Data sources produced in this process:
    • usadfip0251
    • usadfix0251
    Date: 22-Jan-1999 (process 4 of 4)
    Creation of original metadata record Person who carried out this activity:
    Peg Rawson
    U.S. Geological Survey
    521 National Center
    Reston, VA

    703-648-4183 (voice)
    mrawson@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?
    This data set includes an inventory of debris flows and related fast-moving landslides for the conterminous United States, and a susceptibility map covering the same area. This inventory is up-to-date as of August 1999, but there undoubtedly exists a significant amount of information that is not included in this report.
  5. How consistent are the relationships among the observations, including topology?
    No additional checks for topological consistency were performed on this data set.

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. Acknowledgment of the National Atlas of the United States of America and (or) the U.S. Geological Survey would be appreciated in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    USGS Information Services
    Box 25286
    Denver Federal Center
    Denver, CO
    USA

    1-888-ASK-USGS (voice)
    303-202-4693 (FAX)
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. No responsibility is assumed by the U.S. Geological Survey in the use of these data. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 23-Feb-2015
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 Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://geo-nsdi.er.usgs.gov/metadata/map-mf/2329/vector.faq.html>
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