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Seismic Hazard Map for the United States

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Frequently-anticipated questions:


What does this data set describe?

Title: Seismic Hazard Map for the United States
Abstract:
This map layer shows seismic hazard in the United States. The data represent a model showing the probability that ground motion will reach a certain level. This map layer shows peak horizontal ground acceleration (the fastest measured change in speed, for a particle at ground level that is moving horizontally due to an earthquake) with a 10% probability of exceedance in 50 years. Values are given in %g, where g is acceleration due to gravity, or 9.8 meters/second^2. The lines of equal hazard, which
are the lines between the polygons, were determined by interpolating from a grid of equally spaced points in latitude and longitude. Each point was weighted based on the seismic hazard at that location. The grid spacing is 0.1 degrees for Alaska, 0.05 degrees for the conterminous United States, and 0.02degrees for Hawaii.
Supplemental_Information:
This map layer was prepared by combining spatially-smoothed historic seismicity information with information from fault-specific sources. The acceleration values contoured are the random horizontal component. The reference site condition is firm rock, defined as having an average shear- wave velocity of 760 meters/second in the top 30 meters corresponding to the boundary between National Earthquake Hazards Reduction Program (NEHRP) site classes B and C.
For more information about the USGS National Seismic Hazard Maps, please visit http://earthquake.usgs.gov/hazards/index.php.
A description of how the underlying geologic and geophysical data were prepared as well as the methodology used in calculating seismic hazard for a geographic location can be found in the following reports:
Petersen, M.D., Frankel, A.D., Harmsen, S.C., Mueller, C.S., Haller, K.M., Wheeler, R.L., Wesson, R.L., Zeng, Yuehua, Boyd, O.S., Perkins, D.M., Luco, Nicolas, Field, E.H., Wills, C.J., and Rukstales, K.S., 2008, Documentation for the 2008 Update of the United States National Seismic Hazard Maps: U.S. Geological Survey Open-File Report 2008-1128, 61 p.
Klein, F.W., A.D. Frankel, C.S. Mueller, R.L. Wesson and P.G. Okubo, 2001, Seismic Hazard in Hawaii: high rate of large earthquakes and probabilistic ground motion maps, Bulletin of the Seismological Society of America, v. 91, pp. 479-498.
Wesson, Robert L., Boyd, Oliver S., Mueller, Charles S., Bufe, Charles G., Frankel, Arthur D., Petersen, Mark D., 2007, Revision of time-Independent probabilistic seismic hazard maps for Alaska: U.S. Geological Survey Open-File Report 2007-1043, 33p.
  1. How should this data set be cited?

    Rukstales, Kenneth S. (compiler), 201201, Seismic Hazard Map for 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: 172
    East_Bounding_Coordinate: -66
    North_Bounding_Coordinate: 72
    South_Bounding_Coordinate: 18

  3. What does it look like?

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

    Calendar_Date: 2012
    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):

      • GT-polygon composed of chains (3647)

    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 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    Areas of seismic hazard (described by seihazp020.dbf).
    Areas of predicted peak horizontal ground acceleration within the specified range, with a 10% probability of exceedance in 50 years. (Source: U.S. Geological Survey)

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

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

    ValueDefinition
    Polygon2-dimensional element

    Valley
    A code indicating whether the polygon represents a local minima. (Source: U.S. Geological Survey)

    ValueDefinition
    0The polygon is not a local minima.
    1The polygon is a local minima.

    ACC_VAL
    The minimum peak horizontal acceleration value for the polygon, %g. (Source: USGS)

    ValueDefinition
    0 - 1Acceleration values within the polygon range from 0% to 1% g
    1 - 2Acceleration values within the polygon range from 1% to 2% g
    2 - 3Acceleration values within the polygon range from 2% to 3% g
    3 - 4Acceleration values within the polygon range from 3% to 4% g
    4 - 5Acceleration values within the polygon range from 4% to 5% g
    5 - 6Acceleration values within the polygon range from 5% to 6% g
    6 - 7Acceleration values within the polygon range from 6% to 7% g
    7 - 8Acceleration values within the polygon range from 7% to 8% g
    8 - 9Acceleration values within the polygon range from 8% to 9% g
    9 - 10Acceleration values within the polygon range from 9% to 10% g
    10 - 15Acceleration values within the polygon range from 10% to 15% g
    15 - 20Acceleration values within the polygon range from 15% to 20% g
    20 - 25Acceleration values within the polygon range from 20% to 25% g
    25 - 30Acceleration values within the polygon range from 25% to 30% g
    30 - 40Acceleration values within the polygon range from 30% to 40% g
    40 - 60Acceleration values within the polygon range from 40% to 60% g
    60 - 80Acceleration values within the polygon range from 60% to 80% g
    80 - 100Acceleration values within the polygon range from 80% to 100% g
    > 100Acceleration values within the polygon have values >= 100% g


Who produced the data set?

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

    • Rukstales, Kenneth S. (compiler)

  2. Who also contributed to the data set?

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

    Ken Rukstales
    U.S. Geological Survey
    Box 25046, Mail Stop 966
    Denver, CO 80225
    USA

    303-273-8677 (voice)
    303-273-8600 (FAX)
    rukstales@usgs.gov

    Contact_Instructions: Please contact via e-mail or telephone


Why was the data set created?

This map summarizes the quantitative information, available from geologic and geophysical sources, about seismic ground motion hazard in the United States. The 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 1:2,000,000-scale data.
No responsibility is assumed by the U.S. Geological Survey or 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?

    SH-USA (source 1 of 2)
    Petersen, M., Frankel, A., Harmsen, S., Mueller, C., Haller, K., Wheeler, R., Wesson, R., Zeng, Y., Boyd, O., Perkins, D., Luco, N., Field, E., Wills, C., and Rukstales, K., 2011, Seismic-Hazard Maps for the Conterminous United States, 2008: U.S. Geological Survey Scientific Investigations Map 3195, U.S. Geological Survey, Reston, VA.

    Other_Citation_Details: 6 sheets
    Type_of_Source_Media: Paper
    Source_Scale_Denominator: 7000000
    Source_Contribution:
    The publication describes the conterminous United States historical seismicity and fault-specific sources used to build the theoretical model, as well as the methodology employed.

    SH-Hawaii (source 2 of 2)
    Klein, F.W., Frankel, A.D., Mueller, C.S., Wesson, R.L., and Okubo, P.G., 2000, Seismic-Hazard Maps for Hawaii: U.S. Geological Survey Geologic Investigations Series Map I-2724, U.S. Geological Survey, Reston, VA.

    Other_Citation_Details: 2 sheets
    Type_of_Source_Media: Paper
    Source_Scale_Denominator: 2000000
    Source_Contribution:
    The publication describes the Hawaiian historical seismicity and fault specific sources used to build the theoretical model, as well as the methodology employed.

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

    Date: 2012 (process 1 of 1)
    Information drawn from the sources was used to produce an ASCII file of grid points having a latitude and longitude spacing of 0.1 degrees (Alaska), 0.05 degrees (conterminous United States), or 0.02 degrees (Hawaii). For each grid point an associated acceleration value, or weight, was calculated from the historic seismicity and fault-specific sources, according to the prescribed seismological model. The data were then contoured using ArcGIS. The desired final lines of equal seismological hazard were selected and polygon and arc topology were ascertained as well as appropriate feature attributes. The file was converted to Shapefile format.

    Person who carried out this activity:

    Ken Rukstales
    U.S. Geological Survey
    Box 25046, Mail Stop 966
    Denver, Colorado 80225
    USA

    303-273-8677 (voice)
    303-273-8600 (FAX)
    rukstales@usgs.gov

    Contact_Instructions: Please contact via e-mail or telephone
  3. What similar or related data should the user be aware of?

    Petersen, M., Frankel, A., Harmsen, S., Mueller, C., Haller, K., Wheeler, R., Wesson, R., Zeng, Y., Boyd, O., Perkins, D., Luco, N., Field, E., Wills, C., and Rukstales, K., 2011, Seismic-Hazard Maps for the Conterminous United States, 2008: U.S. Geological Survey Scientific Investigations Map 3195, U.S. Geological Survey, Reston, VA.

    Other_Citation_Details: 6 sheets, scale 1:7,000,000
    Klein, F.W., Frankel, A.D., Mueller, C.S., Wesson, R.L., and Okubo, P.G., 2000, Seismic-Hazard Maps for Hawaii: U.S. Geological Survey Geologic Investigations Series Map I-2724, U.S. Geological Survey, Reston, VA.

    Other_Citation_Details: 2 sheets, scale 1:2,000,000


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?

    This map layer is based on a theoretical model. The following resources provide information on quality assessment for the map layer:
    Petersen, M., A. Frankel, S. Harmsen, C. Mueller, K. Haller, R. Wheeler, R. Wesson, Y. Zeng, O. Boyd, D. Perkins, N. Luco, E. Field, C. Wills and K. Rukstales, 2008, Documentation for the 2008 Update of the United States National Seismic-Hazard Maps: U.S. Geological Survey Open-File Report 2008-1128, 61 p.
    Klein, F.W., A.D. Frankel, C.S. Mueller, R.L. Wesson and P.G. Okubo, 2001, Seismic Hazard in Hawaii: high rate of large earthquakes and probabilistic ground motion maps, Bulletin of the Seismological Society of America, v. 91, pp. 479-498.
    Wesson, Robert L., Boyd, Oliver S., Mueller, Charles S., Bufe, Charles G., Frankel, Arthur D., Petersen, Mark D., 2007, Revision of time-Independent probabilistic seismic hazard maps for Alaska: U.S. Geological Survey Open-File Report 2007-1043, 33p.

  2. How accurate are the geographic locations?

    The location of features is based on theoretical calculations of a seismological model for the study area. The location of each point is considered to be correct within the confines of computer accuracy.

  3. How accurate are the heights or depths?

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

    This map layer shows levels of seismic hazard for the United States.

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

    Polygon and chain-node topology are present.
    Uncertainty in the underlying seismicity or fault parameters was not considered in the production of this map layer.


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:
Acknowledgment of the National Atlas of the United States of America and (or) the U.S. Geological Survey, National Seismic Hazard Mapping Project 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: 18-Jan-2012
Metadata author:
Jay Donnelly
National Atlas of the United States
12201 Sunrise Valley Dr
Reston, VA 20192
USA

703-648-5395 (voice)
atlasmail@usgs.gov

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



 


Generated by mp version 2.9.13 on Mon Jan 23 10:13:09 2012