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In develpoing the hazard model for South America, the USGS considered the ground motion models (GMM) used for the conterminous United States because most of the equations consider global earthquakes and because the U.S. and South America are seismically quite similar, with the potential for active subduction, deep intraslab, crustal, and craton earthquakes. Included here is a table that summarizes the GMMs selected for each of the earthquake types and the weight applied within the model.
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The 2021 update of the U.S. National Seismic Hazard Model for Hawaii succeeds the twenty-year-old former model by incorporating new data and modeling techniques to improve the ground shaking forecasts. Output from the model 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 between 0.01 and 10 second, and for eight separate soil site classes (VS30 = 1500 m/sec to 150 m/sec), representing NEHRP site classes A/B to E. In addition, gridded uniform- hazard data are provided...
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This maps portrays the spatial potential for damaging earthquake ground shaking quantified as considerable (MMI ≥ VIII) in 100 years. The maps and data are based on the average of the results obtained from peak ground acceleration and 1.0-second horizontal spectral acceleration. Site specific soil factors based on Vs30 shear wave velocities were implemented using a simple topographic proxy technique (Allen and Wald, 2009) and site amplification based on the relationships of Seyhan and Stewart (2014). MMI ≥ VIII is equivalent to peak ground acceleration of 0.40g and 1.0-second horizontal spectral acceleration of 0.50g (Worden et al., 2012). Allen, T.A. and Wald, D.J. 2009,. On the use of high-resolution topographic...
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This maps portrays the spatial potential for damaging earthquake ground shaking quantified as slight (MMI ≥ VI) in 100 years. The maps and data are based on the average of the results obtained from peak ground acceleration and 1.0-second horizontal spectral acceleration. Site specific soil factors based on Vs30 shear wave velocities were implemented using a simple topographic proxy technique (Allen and Wald, 2009) and site amplification based on the relationships of Seyhan and Stewart (2014). MMI ≥ VI is equivalent to peak ground acceleration of 0.12g and 1.0-second horizontal spectral acceleration of 0.1g (Worden et al., 2012). Allen, T.A. and Wald, D.J. 2009,. On the use of high-resolution topographic data...
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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 10 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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We produce the USGS 2018 one-year probabilistic seismic hazard forecast for the central and eastern United States from induced and natural earthquakes. For consistency, the updated 2018 forecast is developed using the same probabilistic seismicity-based methodology as applied in the two previous forecasts for 2016 and 2017. Rates of earthquakes across the U.S. (M ≥ 3.0) grew rapidly between 2008 and 2015 but have steadily declined over the past three years, especially in areas of Oklahoma and southern Kansas where fluid injection has decreased. The seismicity pattern in 2017 was complex with earthquakes more spatially dispersed than in previous years. Some areas of west-central Oklahoma experienced increased activity...
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Expected average annual losses from earthquakes are determined by using PAGER's vulnerability functions that are unique to each country. There are significant differences in economic losses between countries, which is indicative of their relative vulnerability to earthquakes.
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Probabilistic seismic-hazard maps were prepared for the conterminous United States that portray peak horizontal acceleration and horizontal spectral response acceleration for 0.2, 1.0, and 5.0 second periods with a probability of exceedance of 2%, 5%, and 10% percent in 50 years. Maps and data are available for NEHRP site class B/C and D (Vs30 equal to 760 m/s and 260 m/s). 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.
Categories: Data
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These data were calculated to estimate seismic hazard, risk, and design across South America using the latest data, models, and methods. The input data to the model, as well as the output data are available here. The input data includes a seismicity catalog, seismicity rate models, evaluation of earthquake sizes, fault geometry and rate parameters, and ground-motion models. Output data include hazard curves, and associated products, for peak ground acceleration and spectral accelerations at 0.2 and 1 s periods.
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 hazard curves for a grid of points with a spacing of 0.1 degrees in latitude and longitude. It represents the annual rate of exceedance versus 1.0-second spectral response acceleration.
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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 50 percent probability of exceedance in 50 years.
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Expected average annual fatalities from earthquakes are determined by using PAGER's vulnerability functions that are unique to each country. There are significant differences in fatality rates between countries, which is indicative of their relative vulnerability to earthquakes.
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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 2 percent probability of exceedance in 50 years.
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Local seismic velocity data that influence long-period ground shaking were considered for four urban basin regions in the western United States. Depth to shear wave velocities of 2.5 km/s (Z2.5) and 1.0 km/s (Z1.0) used in the NGA-West2 ground-motion models to account for basin amplification are available here.
Categories: Data
For designing buildings and other structures, the 2020 NEHRP Recommended Seismic Provisions and the 2022 ASCE/SEI 7 Standard provide Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations and Maximum Considered Earthquake Geometric Mean (MCEG) peak ground accelerations. The MCER ground motions are also expected to be in the 2023 ASCE/SEI 41 Standard and the 2024 and 2027 editions of the International Building Code. Both sets of ground motions are derived from USGS National Seismic Hazard Models via the gridded values of this data release. The files in the "Child Items" below also underlie corresponding USGS Seismic Design Web Services. See the "Related External Resources" below for...
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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 1.0-second spectral response acceleration are available here.
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Seismic hazard assessments depend on an accurate prediction of ground motion, which in turn depends on a base knowledge of three-dimensional variations in density, seismic velocity, and attenuation. The datasets here are components of a National Crustal Model that couples geologic characteristics and geophysical parameters using a physical theoretical foundation combined with measured data for calibration. The model is intended to be internally consistent and seamless on a national scale; care is also taken to maximize consistency with existing regional models. An initial version of the model components are defined for the western U.S. on a 1-km grid. While the current focus of this effort is on improving estimates...
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Hazard curves for VS30 equal to 760 m/s and 260 m/s (NEHRP site class B/C and D), for 0.2, 1.0, and 5.0 second periods, as well as PGA, are available for download below. The data are for a 0.05o by 0.05o grid of points covering the conterminous United States. Hazard curves for addtional periods and site classes can be found here. While the gridded hazard curve data includes ground motions at long return periods, the USGS does not recommend using hazard values below 10-5 (100,000 years), and cautions users using values below 10-4 (10,000 years). These models were developed for building codes concerned with return periods of 10-4 and above.
map background search result map search result map Seismic Hazard, Risk, and Design for South America 1.0-second spectral response acceleration (5% of critical damping) with a 2% probability of exceedance in 50 years Peak ground acceleration with a 50% probability of exceedance in 50 years Modified Mercalli Intensity, based on peak ground acceleration, with a 10% probability of exceedance in 50 years Data Release for 2018 One-Year Seismic Hazard Forecast for the Central and Eastern United States from Induced and Natural Earthquakes Components of the USGS National Crustal Model 1. Hazard curves for the 2018 update of the U.S. National Seismic Hazard Model Data Release for the 2021 Update of the U.S. National Seismic Hazard Model for Hawaii Data Release for the 2021 Update of the U.S. National Seismic Hazard Model for Hawaii Components of the USGS National Crustal Model 1. Hazard curves for the 2018 update of the U.S. National Seismic Hazard Model Data Release for 2018 One-Year Seismic Hazard Forecast for the Central and Eastern United States from Induced and Natural Earthquakes Seismic Hazard, Risk, and Design for South America Peak ground acceleration with a 50% probability of exceedance in 50 years 1.0-second spectral response acceleration (5% of critical damping) with a 2% probability of exceedance in 50 years Modified Mercalli Intensity, based on peak ground acceleration, with a 10% probability of exceedance in 50 years