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Deprecated[64242] Earthquake Hazards Program

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The 2002 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. This update of the maps incorporates new findings on earthquake ground shaking, faults, seismicity, and geodesy. The resulting maps are derived from seismic hazard curves calculated on a grid of sites across the United States that describe the frequency of exceeding a set of ground motions.
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A comparison of the 2017 USGS South America seismic hazard model with the Global Seismic Hazard Assessment Program (GSHAP) model and the 2010 USGS preliminary model was made to see how the models differ. The comparisons were made as ratios of PGA at 10% probability of exceedance in 50 years. Ratio maps of each comparison are included as a geo-referenced tiff (GeoTIFF).
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The U.S. Geological Survey (USGS) national seismic hazard models (NSHM) consider two kinds of earthquake sources. Specific faults are modeled where possible. Where faults cannot be identified or characterized, alternative sources can be developed from seismicity catalogs. In a paper submitted to Seismological Research Letters ("Related External Resources", below), we describe a methodology that has been developed at the USGS for making earthquake catalogs for seismic hazard analysis. In this data release we provide the catalogs for the conterminous U.S. that accompany the SRL article. A new catalog is assembled from several preexisting catalogs. Moment magnitudes and related parameters for modeling seismicity...
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We generated digital elevation models (DEMs) using pre- and post-event in-track stereo 0.5 m resolution panchromatic Worldview 1 and 2 images (©2019, DigitalGlobe) using the Surface Extraction from TIN-based Searchspace Minimization (SETSM) software [Noh and Howat, 2015] running on the University of Iowa Argon supercomputer (Table S1). The post-event DEMs exhibit along-track striping artifacts common to the Worldview 2 sensor. While de-striping tools, for example within NASAs Ames Stereo Pipeline [Shean et al., 2016], are commonly applied to resolve this issue, a de-striping correction has not been developed for this latitude. Noh, M.-J., and I. M. Howat (2015), Automated stereo-photogrammetric DEM generation...
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A seismic hazard model for South America, based on a smoothed (gridded) seismicity model, a subduction model, a crustal fault model, and a ground motion model, has been produced by the U.S. Geological Survey. These models are combined to account for ground shaking from earthquakes on known faults as well as earthquakes on un-modeled faults. This data set represents the results of calculations of hazard curves for a grid of points with a spacing of 0.1 degrees in latitude and longitude. This particular data set is for peak ground acceleration with a 10 percent probability of exceedance in 50 years.
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