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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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This data set represents the results of calculations of hazard curves for a grid of points with a spacing of 0.05 degrees in latitude and longitude. This particular data set is for horizontal spectral response acceleration for 0.2-second period with a 1 percent probability of exceedance in 1 year. The data are for the Western United States and are based on the long-term 2014 National Seismic Hazard Model.
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These data sets are the results of calculations of hazard curves for a grid of points with a spacing of 0.05 degrees in latitude and longitude. They represent the chance of experiencing potentially damaging ground shaking for fixed ground shaking levels that corresponds with MMI = VII. The values are obtained by averaging the probability of experiencing MMI = VII based on a peak ground acceleration value of 0.2152 g for site class D, and the probability of experiencing MMI = VII based on 1.0-second spectral acceleration value of 0.2256 g for site class D. The data are for the Central and Eastern United States.
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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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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 horizontal spectral response acceleration for 0.2-second period with a 50 percent probability of exceedance in 50 years.
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Seismic hazard curves were determined using the USGS seismic hazard model for South America. The curves represent the annual rate of exceedance versus peak horizontal acceleration or horizontal spectral response acceleration for 0.2- or 1.0-second periods, for a grid of points with a spacing of 0.1 degrees in latitude and longitude. The hazard curves were used to prepare maps and gridded data that portray peak horizontal acceleration and horizontal spectral response acceleration for 0.2- and 1.0-second periods with a 2%, 10%, and 50% probability of exceedance in 50 years, and a uniform site condition (Vs30) of 760 m/sec. MMI maps for 2%, 10%, and 50% probability of exceedance in 50 years were derived from PGA...
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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 horizontal spectral response acceleration for 1.0-second period with a 10 percent probability of exceedance in 50 years.
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A comparison of the 2017 USGS South America seismic hazard model and the 2010 USGS preliminary model was made to see how the models differ. The comparison was made as the ratio of PGA at 10% probability of exceedance in 50 years. The ratio map is included here as a geo-referenced tiff (GeoTIFF). The gridded data for the 2017 PGA at 10% probability can be found here, while the gridded data for the 2010 PGA at 10% probability can be found in the zip archive that can be downloaded using a link on this page.
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Maximum considered earthquake geometric mean peak ground acceleration maps (MCEG) are for assessment of the potential for liquefaction and soil strength loss, as well as for determination of lateral earth pressures in the design of basement and retaining walls. The maps are derived from the USGS seismic hazard maps in accordance with the site-specific ground-motion procedures of the NEHRP Recommended Seismic Provisions for New Building and Other Structures and the ASCE Minimum Design Loads for Buildings and Other Structures (also known as the ASCE 7 Standard; ASCE, 2016). The MCEG ground motions are taken as the lesser of probabilistic and deterministic values, as explained in the Provisions. The gridded probabilistic...
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A comparison of the 2017 USGS South America seismic hazard model and the Global Seismic Hazard Assessment Program (GSHAP) model was made to see how the models differ. The comparison was made as the ratio of PGA at 10% probability of exceedance in 50 years. The ratio map is included here as a geo-referenced tiff (GeoTIFF). The gridded data for the 2017 PGA at 10% probability can be found here, while the GSHAP data can be found here. Shedlock, K.M., Giardini, Domenico, Grünthal, Gottfried, and Zhang, Peizhan, 2000, The GSHAP Global Seismic Hazar Map, Sesimological Research Letters, 71, 679-686. https://doi.org/10.1785/gssrl.71.6.679
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The crustal fault model accounts for earthquakes that occur on faults that have not ruptured recently, but have have been active in historic and prehistoric periods. Although hundreds of Quaternary faults have been mapped, only a few of these faults have been studied sufficiently to reach a consensus regarding rate of deformation that can be applied in this hazard assessment. Information regarding the seismogenic source geometry and seismogenic source behavior that is necessary to model each fault is included for each fault. Files that can be used as input to computer hazard code are included.
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This data set represents the results of calculations of hazard curves for a grid of points with a spacing of 0.05 degrees in latitude and longitude. This particular data set is for horizontal spectral response acceleration for 1.0-second period with a 1 percent probability of exceedance in 1 year. The data are for the Western United States and are based on the long-term 2014 National Seismic Hazard Model.
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Output from the 2021 National Seismic Hazard Model for Hawaii includes probabilistic seismic hazard curves calculated for a 0.02° x 0.02° grid of latitude/longitude locations across Hawaii. The new model provides an expanded suite of hazard curves for twenty-three different ground motion intensity measures, including PGA, PGV, and spectral accelerations for 0.01, 0.02, 0.03, 0.05, 0.075, 0.1, 0.15, 0.2, 0.25, 0.3, 0.4, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 7.5 and 10 second, and eight separate soil site classes (VS30 = 1500, 1080, 760, 530, 365, 260, 185, and 150 m/sec), representing NEHRP site classes A/B, B, B/C, C, C/D, D, D/E, and E. This data set represents the hazard curves for a grid of points with a spacing...
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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 Modified Mercalli Intensity with a 50 percent probability of exceedance in 50 years. The maps and data were derived from PGA ground-motion conversions of Worden et al. (2012), and include soil amplification...
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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 horizontal spectral response acceleration for 0.2-second period with a 2 percent probability of exceedance in 50 years.
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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 2 percent probability of exceedance in 50 years.
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The subduction model accounts for large earthquakes (M 7–9.5) that occur on the subduction interface. The subduction zones along the northern and western coast of South America, the Panama deformation zones, and the Lesser Antilles subduction zone of the Caribbean are considered in the subduction model of this hazard assessment. The subduction interface of the Nazca plate beneath the western coast of South America has been separated into five zones, down to a depth of 50 km. The five zones are based on the locations of impinging subduction ridges, dimensions of large earthquakes, and fault complications. An alternative model for Chile (Medina et al., 2017) is applied to the Nazca subduction zones 3–5. This...
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Peak ground acceleration ground motion values for 50, 10, and 2 percent probability of exceedance in 50 years are converted to equivalent modified Mercalli intensity using the relationships of Worden and others (2012). Values are for NEHRP site class B/C with a VS30 = 760 m/s.
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The b-value for the earthquake catalog from the Oklahoma-Kansas potentially induced earthquake zone is computed with the maximum likelihood method (MLE) (Aki, 1965). We use the minimum magnitude of completeness that is used for the seismicity rate models (Mc=2.7) and the earthquakes from 2016 and 2017 and find b=1.5 (1.48+/-0.05). However, we find that the b-value from the full (non-declustered) catalog is sensitive to the minimum magnitude of completeness, perhaps due to the moment magnitudes at these values being highly dependent on the conversion relations and the measurements of local magnitudes. Aki, K. (1965). Maximum likelihood estimate of b in the formula log N= a-bM and its confidence limits. Bull. Earthq....
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Risk-targeted maximum considered earthquake ground acceleration maps (MCER) are for the design of buildings and other structures. The maps are derived from the USGS seismic hazard maps in accordance with the site-specific ground-motion procedures of the NEHRP Recommended Seismic Provisions for New Building and Other Structures and the ASCE Minimum Design Loads for Buildings and Other Structures (also known as the ASCE 7 Standard; ASCE, 2016). The MCER ground motions are taken as the lesser of probabilistic and deterministic values, as explained in the Provisions. The gridded probabilistic and deterministic values for 0.2-second spectral response acceleration are available here.
map background search result map search result map 2) Probabilistic seismic hazard maps and data for South America Peak ground acceleration with a 2% probability of exceedance in 50 years Peak ground acceleration with a 10% probability of exceedance in 50 years 0.2-second spectral response acceleration (5% of critical damping) with a 2% probability of exceedance in 50 years 1.0-second spectral response acceleration (5% of critical damping) with a 10% probability of exceedance in 50 years Crustal fault model Subduction model 3) Comparison with previous models Comparison with the 2010 USGS preliminary model Comparison with the 1999 Global Seismic Hazard Assessment (GSHAP) model 0.2-second spectral response acceleration (5% of critical damping) with a 50% probability of exceedance in 50 years Modified Mercalli Intensity, based on peak ground acceleration, with a 50% probability of exceedance in 50 years Chance of potentially moderate-damage ground shaking in 2018 based on the average of horizontal spectral response acceleration for 1.0-second period and peak ground acceleration for the Central and Eastern United States 0.2-second spectral response acceleration (5% of critical damping) with a 1% probability of exceedance in 1 year for the Western United States 1.0-second spectral response acceleration (5% of critical damping) with a 1% probability of exceedance in 1 year for the Western United States 01. Hazard curves 07. Modified Mercalli Intensity maps for the conterminous U.S., Alaska, and Hawaii 01. Hazard curves 0.2-second spectral response acceleration (5% of critical damping) with a 1% probability of exceedance in 1 year for the Western United States 1.0-second spectral response acceleration (5% of critical damping) with a 1% probability of exceedance in 1 year for the Western United States Chance of potentially moderate-damage ground shaking in 2018 based on the average of horizontal spectral response acceleration for 1.0-second period and peak ground acceleration for the Central and Eastern United States Crustal fault model Subduction model Comparison with the 2010 USGS preliminary model Comparison with the 1999 Global Seismic Hazard Assessment (GSHAP) model 2) Probabilistic seismic hazard maps and data for South America 3) Comparison with previous models 1.0-second spectral response acceleration (5% of critical damping) with a 10% probability of exceedance in 50 years 0.2-second spectral response acceleration (5% of critical damping) with a 2% probability of exceedance in 50 years 0.2-second spectral response acceleration (5% of critical damping) with a 50% probability of exceedance in 50 years Peak ground acceleration with a 2% probability of exceedance in 50 years Peak ground acceleration with a 10% probability of exceedance in 50 years Modified Mercalli Intensity, based on peak ground acceleration, with a 50% probability of exceedance in 50 years 07. Modified Mercalli Intensity maps for the conterminous U.S., Alaska, and Hawaii