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Quaternary Fault and Fold Database of the United States

Metadata also available as - [Outline] - [Parseable text] - [XML] - [DIF]

Frequently-anticipated questions:


What does this data set describe?

Title: Quaternary Fault and Fold Database of the United States
Abstract:
This map layer contains locations and information on faults and associated folds, in the United States, that are believed to be sources of significant earthquakes (those of magnitude 6 or greater) during the past 1,600,000 years.

Supplemental_Information:
The most up-to-date version of this data set as well as detailed descriptions and references for each fault are available through the online Quaternary Fault and Fold Database of the United States, at <http://earthquake.usgs.gov/regional/qfaults/>. In addition, in the Earthquake Hazards Program Quaternary Faults and Fold Database viewer <http://gldims.cr.usgs.gov/qfault/viewer.htm>, and in the National Atlas Map Maker <http://nationalatlas.gov/mapmaker>, the geologic structures are linked to the database. The Quaternary Fault and Fold Database of the United States is intended to be the USGS archive for historic and ancient earthquake sources used in current and future probabilistic seismic-hazard analyses. The database summarizes important information on paleoseismic (ancient earthquake) parameters, compiled from thousands of journal articles, maps, theses, and other documents. It includes information on geographic, geologic, and paleoseismic parameters that are deemed critical to making geologic-based assessments of seismic hazards. In addition, it provides narrative comments that clarify, justify, or expound upon these parameters.

  1. How should this data set be cited?

    Kathy Haller, U.S. Geological Survey, Richard Dart, U.S. Geological Survey, and Susan Rhea, U.S. Geological Survey, 200501, Quaternary Fault and Fold Database of the United States: National Atlas of the United States, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -126.39
    East_Bounding_Coordinate: -70.81
    North_Bounding_Coordinate: 48.89
    South_Bounding_Coordinate: 23.19

  3. What does it look like?

    <http://gldims.cr.usgs.gov/qfault/viewer.htm> (Online viewer)
    Viewer for the Quaternary Fault and Fold Database.

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2005
    Currentness_Reference: Publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: Vector digital data

  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 (24)
      • Complete chain (45814)

    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 0.000278. Longitudes are given to the nearest 0.000278. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    Quaternary faults (described by qfaultl_25.dbf)
    Linear fault features in the conterminous United States. (Source: U.S. Geological Survey)

    Shape
    The representation of the entity in the data. (Source: National Atlas of the United States)

    ValueDefinition
    Polyline1-dimensional element that may or may not surround a 2-dimensional element.

    Qfaultl_25
    Internal feature number. (Source: National Atlas of the United States)

    Range of values
    Minimum:1
    Maximum:45814

    Name
    The fault name. (Source: U.S. Geological Survey)

    ValueDefinition
    <Blank>The fault name is unknown.

    There is no predefined set of valid fault names.

    Code
    A 3-digit code used for symbolizing faults. Each digit has a particular meaning:
    
    First digit: fault visibility code
    1 = Exposed
    2 = Concealed
    3 = Inferred
    
    Second digit: fault age code
    1 = Historic; referenced in dated recorded history, generally < 150
        years
    2 = Holocene < 15,000 years
    3 = Late Quaternary < 130,000 years
    4 = Mid to late Quaternary < 750,000 years
    5 = Quaternary < 1,600,000 years
    6 = Class B; fault structures of questionable seismogenic origin that
        may be older than the Quaternary
    
    Third digit: fault slip rate code
    1 = > 5 mm/year
    2 = 1 - 5 mm/year
    3 = 0.2 – 1 mm/year
    4 = < 0.2 mm/year
    
    (Source: National Atlas of the United States)

    There is no predefined set of valid fault codes.

    Num
    The fault index number, which is linked to the online fault database. (Source: U.S. Geological Survey)

    ValueDefinition
    <Blank>There is no information about the fault available in the online fault database.

    There is no predefined set of valid fault index numbers.

    Slip
    A four-character code defining the fault type and slip direction. The first two characters describe the fault type:
    N_ = normal
    R_ = reverse
    SS = strike-slip
    T_ = thrust
    
    
    The second two characters describe the slip direction:
    __ = no data
    C_ = center
    E_ = east
    LL = left lateral
    N_ = north
    NE = northeast
    NW = northwest
    RL = right lateral
    S_ = south
    SE = southeast
    SW = southwest
    W_ = west
    
    
    (Source: U.S. Geological Survey)

    ValueDefinition
    <Blank>The fault type and slip direction are not known.

    There is no predefined set of valid slip codes.

    Age
    The age of the fault in years. (Source: U.S. Geological Survey)

    ValueDefinition
    <1,600,000The fault is less than 1,600,000 years old.
    <750,000The fault is less than 750,000 years old.
    <130,000The fault is less than 130,000 years old.
    <15,000The fault is less than 15,000 years old.
    <150The fault is historic (less than 150 years old.)
    Class BClass B faults may or may not be seismogenic (capable of generating earthquakes) and may be older than the Quaternary.
    UnknownThe age is undetermined, but researchers believe that fault motion occurred in the Quaternary.

    Rate
    The rate of motion obtained when the amount of offset is divided by the time interval. It is normalized to millimeters per year. (Source: U.S. Geological Survey)

    ValueDefinition
    <0.2The rate of motion is less than 0.2 millimeters per year.
    0.2-1The rate of motion is 0.2 to 1 millimeters per year.
    1-5The rate of motion is 1 to 5 millimeters per year.
    >5The rate of motion is greater than 5 millimeters per year.

    Slipsense
    The angle of dip of the fault and the relative direction of movement across the fault. (Source: U.S. Geological Survey)

    ValueDefinition
    IncompleteThe angle of dip and the relative direction of movement were not reported in the referenced material for the fault.
    LeftLateralHorizontal displacement along a fault such that, in plan view, the side opposite the viewer appears to have moved to the left. This term is also known as sinistral.
    NormalA fault characterized by predominantly vertical displacement in which the hanging wall moves downward with respect to the footwall of the fault. If the fault surface is exposed, the footwall is the side onto which water would drip. Generally, this type of fault is a sign of tectonic extension.
    ReverseA fault in which the displacement is predominantly vertical, and the hanging wall moves up with respect to the footwall. The footwall is the side of the fault onto which water would drip if the fault is exposed.
    RightLateralHorizontal displacement along a fault such that, in plan view, the side opposite the viewer appears to have moved to the right. This term is also known as dextral.
    ThrustA fault of less than 45 dip in which the displacement is predominantly vertical, and the hanging wall moves up with respect to the footwall. The footwall is the side of the fault onto which water would drip if the fault is exposed.

    Dipdirecti
    The general direction of the fault dip which is the angle that the fault is inclined from the horizontal plane. (Source: U.S. Geological Survey)

    ValueDefinition
    CenterThe direction of the dip is towards the center of a hole or depression, as in a caldera or bowl.
    EastThe direction of the dip is toward the east.
    NorthThe direction of the dip is toward the north.
    NortheastThe direction of the dip is toward the northeast.
    NorthwestThe direction of the dip is toward the northwest.
    SouthThe direction of the dip is toward the south.
    SoutheastThe direction of the dip is toward the southeast.
    SouthwestThe direction of the dip is toward the southwest.
    UnspecifiedThe direction of the dip is unknown.
    VerticalThe fault face is near vertical.
    WestThe direction of the dip is toward the west.

    Acode
    A code indicating the age of the fault in years before the present. The code is used for symbolizing the lines in the map service and the National Atlas. (Source: U.S. Geological Survey)

    ValueDefinition
    1The fault age is historic.
    2The fault age is Holocene, <15,000 years.
    3The fault age is late Quaternary, <130,000 years.
    4The fault age is mid-late Quaternary, <750,000 years.
    5The fault age is Quaternary, <1,600,000 years.
    6The fault age is class B. It is not thought to be seismogenic (capable of producing earthquakes) and may be older than the Quaternary.

    Wwwurl
    An identification code used to locate data in the online database. This is used by the interactive map service at <http://gldims.cr.usgs.gov/qfault/viewer.htm> and by <http://nationalatlas.gov/mapmaker> (Source: U.S. Geological Survey)

    ValueDefinition
    0No information about the fault is available in the online database.

    Range of values
    Minimum:84
    Maximum:35110

    Quaternary fault areas (described by qfaultp_25.dbf)
    Fault feature regions in the conterminous United States. (Source: U.S. Geological Survey)

    Shape
    The representation of the entity in the data. (Source: National Atlas of the United States)

    ValueDefinition
    Polygon2-dimensional element

    Area
    The size of the shape in square coverage units. In the distributed file, coverage units represent square decimal degrees. (Source: National Atlas of the United States)

    Range of values
    Minimum:0.002
    Maximum:28.349

    Perimeter
    The perimeter of shape in coverage units. In the distributed file, coverage units represent decimal degrees. (Source: National Atlas of the United States)

    Range of values
    Minimum:0.191
    Maximum:28.754

    Qfaultp_25
    Internal feature number. (Source: National Atlas of the United States)

    Range of values
    Minimum:2
    Maximum:25

    Name
    The name of the fault region. (Source: U.S. Geological Survey)

    There is no predefined set of valid fault region names.

    Age_class
    A code indicating the age of the faults in years before the present. The code is used for symbolizing the area in the map service and the National Atlas. (Source: U.S. Geological Survey)

    ValueDefinition
    1The fault age is historic, <150 years - 400 years.
    2The fault age is Holocene < 15,000 years.
    3The fault age is late Quaternary < 130,000 years.
    6The fault age is class B. It is not thought to be seismogenic, and may be older than the Quaternary.

    Num
    The fault index number(s), which is linked to the online database. (Source: U.S. Geological Survey)

    There is no predefined set of valid fault index numbers.

    Age
    The age of the faults in years before the present. (Source: U.S. Geological Survey)

    ValueDefinition
    <1,600,000The faults are less than 1,600,000 years old.
    <15,000The faults are less than 15,000 years old.
    nodataNo data are available to determine the fault ages.
    variousMultiple ages were reported.

    Rate
    The rate of motion obtained when the amount of offset is divided by the time interval. It is normalized to millimeters per year. (Source: U.S. Geological Survey)

    ValueDefinition
    <0.2The rate of motion is less than 0.2 millimeters per year.
    nodataThe rate of motion is unknown; no data is available.
    too few dataNot enough data are available to determine the rate of motion.

    Slipsense
    The angle of dip of the faults and the relative direction of movement across the faults. (Source: U.S. Geological Survey)

    ValueDefinition
    nodataNo data is available to determine the angle of dip.
    normalA fault characterized by predominantly vertical displacement in which the hanging wall moves downward with respect to the footwall of the fault. If the fault surface is exposed, the footwall is the side onto which water would drip. Generally, this type of fault is a sign of tectonic extension.
    sinistralHorizontal displacement along a fault such that, in plan view, the side opposite the viewer appears to have moved to the left. This term is also known as left lateral.
    variousFaults are in a combination of dip directions.

    Dipdirection
    The general direction of the fault dip, which is the angle that a fault is inclined from the horizontal plane. (Source: U.S. Geological Survey)

    ValueDefinition
    S, NThe dips are toward the south and the north.
    SE, NWThe dips are toward the southeast and the northwest.
    SWThe dips are toward the southwest.
    SW, NEThe dips are toward the southwest and the northeast.
    V, SWThe dips are toward the southwest and the vertical.
    nodataThe direction of the dips is unknown.
    variousThe direction of the dips varies.

    Wwwurl
    An identification code used to locate data in the online database. This is used by the interactive map service at <http://gldims.cr.usgs.gov/qfault/viewer.htm> and by <http://nationalatlas.gov/mapmaker> (Source: U.S. Geological Survey)

    ValueDefinition
    0No information about the fault is available in the online database.

    Range of values
    Minimum:33814
    Maximum:34137


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

    • Kathy Haller, U.S. Geological Survey
    • Richard Dart, U.S. Geological Survey
    • Susan Rhea, U.S. Geological Survey

  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Kathleen M Haller
    U.S. Geological Survey
    P.O. Box 25046
    Denver, CO 80225-0046
    USA

    303-273-8616 (voice)
    303-273-8600 (FAX)
    <http://earthquake.usgs.gov/contactus/sitemail.php>


Why was the data set created?

These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:250,000-scale data. No responsibility is assumed by the National Atlas of the United States in the use of these data.


How was the data set created?

  1. From what previous works were the data drawn?

    QFAULT (source 1 of 1)
    U.S. Geological Survey, 2004, Quaternary Fault and Fold Database of the United States: U.S. Geological Survey, Denver, CO.

    Online Links:

    Type_of_Source_Media: Electronic mail system
    Source_Contribution: Spatial and attribute information

  2. How were the data generated, processed, and modified?

    Date: Dec-2004 (process 1 of 1)
    The U.S. Geological Survey Earthquake Hazards Program provided a shapefile that was modified for use in the National Atlas Map Maker. The file was reprojected and the datum was converted from the North American Datum of 1927 to the North American Datum of 1983.

    In addition, in the area of overlapping polygons, two polygons were created, one for "St Louis-Cape Giradeau liquefaction" and one for "Wabash Valley liquefaction features".

    Data sources used in this process:

    • QFAULT

  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?

    Fault characteristics, even where known in detail, are reported in broad categories (for example "age less than 1,600,000 years"). The textual database contains more specific information about each fault where details were available in published literature.

  2. How accurate are the geographic locations?

    Locations of faults were taken from published literature; these investigations were carried out at a variety of scales of observation, hence some faults will be located more precisely and accurately than others. In general the locations are accurate as observed on a 1:250,000 scale map, or within approximately 450 feet.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Faults in Alaska and Hawaii are not included. Data for California are incomplete; not all faults are included.

  5. How consistent are the relationships among the observations, including topology?

    Due to substantial differences in the geological setting and tectonic activity, the central and eastern United States appear to have fewer faults active in the Quaternary. This is partly a real phenomenon (the western US has more tectonic activity) and partly a detection problem. For example, the glacial sediments that cover much of the eastern Midwest conceal the evidence that would be used to infer movement along underlying faults in the Quaternary.


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 Quaternary Faults and Fold Database, the U.S. Geological Survey, and (or) the National Atlas of the United States of America would be appreciated in products derived from these data.

  1. Who distributes the data set? (Distributor 1 of 1)

    Earth Science Information Center, U.S. Geological Survey
    507 National Center
    Reston, VA 20192

    1-888-ASK-USGS (1-888-275-8747) (voice)

    Contact_Instructions:
    In addition to the address above there are other ESIC offices throughout the country. A full list of these offices is at <http://ask.usgs.gov/esic_index.html>.

  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.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 08-Aug-2006
Metadata author:
Peg Rawson
National Atlas of the United States
12201 Sunrise Valley Dr
Reston, VA 20192

703-648-4183 (voice)
atlasmail@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)



 


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