SeismicHazard : public <<Feature>> class
Created: 9/25/2007 11:48:28 AM
Modified: 9/25/2007 12:28:15 PM
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<p>This map layer shows seismic hazard in the United States.  The data<br/></p><p>represent a model showing the probability that ground motion will reach a<br/></p><p>certain level.  This map layer shows peak horizontal ground acceleration<br/></p><p>(the fastest measured change in speed, for a particle at ground level that<br/></p><p>is moving horizontally due to an earthquake) with a 10% probability of<br/></p><p>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<br/></p><p>weighted based on the seismic hazard at that location.  The grid spacing<br/></p><p>is 0.1 degrees for Alaska and the conterminous United States, and 0.02<br/></p><p>degrees for Hawaii.<br/></p><p><br/></p><p>This map summarizes the quantitative information, available from geologic and geophysical sources, about seismic ground motion hazard in the United States.  <br/></p><p>The data are intended for geographic display and analysis at the<br/></p><p>national level, and for large regional areas.  The data should be<br/></p><p>displayed and analyzed at scales appropriate for 1:2,000,000-scale data.<br/></p><p><br/></p><p>No responsibility is assumed by the U.S. Geological Survey or the National Atlas of the United States in the use of these data.<br/></p><p><br/></p><p>This map layer was prepared by combining spatially-smoothed historic<br/></p><p>seismicity information with information from fault-specific sources.  The<br/></p><p>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.<br/></p><p><br/></p><p>For more information about the USGS National Seismic Hazard Maps, please<br/></p><p>visit <http://earthquake.usgs.gov/research/hazmaps/index.php.<br/></p>
Attribute Details
public Number
  SeismicHazardMinimumPeakHorizontalAccelerationNumeric
Notes: The minimum peak horizontal ground acceleration value for the polygon,<br />as percent of gravity (9.8 meters/second2).  Valid values are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 60, 80, and 100.<br />Definition Source: National Atlas of the United States
public String
  SeismicHazardValleyCode
Notes: A code indicating whether the polygon represents a local minima.
Object Type Connection Notes
«Feature» Hazard Class Generalization