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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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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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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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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.
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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 50 percent probability of exceedance in 50 years.
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The 2018 Update of the U.S. National Seismic Hazard Model defines the potential for earthquake ground shaking for various probability levels across the conterminous United States and is applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. The updated model represents an assessment of the best available science in earthquake hazards and incorporates new findings on earthquake ground shaking, seismicity, and long-period amplification over deep sedimentary basins. The new model represents an update of the seismic hazard model; previous versions were developed in 1996, 2002, 2008, and 2014. The output from the National Seismic Hazard Model is a suite...
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This maps portrays the spatial potential for damaging earthquake ground shaking quantified as moderate (MMI ≥ VII) 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 ≥ VII is equivalent to peak ground acceleration of 0.22g and 1.0-second horizontal spectral acceleration of 0.23g (Worden et al., 2012). Allen, T.A. and Wald, D.J. 2009,. On the use of high-resolution topographic...
The smoothed seismicity model is based on a uniform seismicity catalog that is used to assess the location and rate of future earthquakes. This catalog is declustered by removing foreshocks and aftershocks so that only independent events are considered, as required in the probabilistic probabilistic methodolgy used to assess seismic hazard. Future seismicity rates are estimated by counting historical earthquakes in a grid with a cell dimension of 0.1 degrees in latitude and longitude. These gridded earthquake rates are smoothed using a 50 kilometer fixed length smoothing kernel. Separate rate models were developed for the craton and active tectonic regions for earthquake depths between 0 and 50 km. Gridded...
For designing buildings and other structures, the 2015 NEHRP Recommended Seismic Provisions and the 2016 ASCE/SEI 7 Standard contain maps of Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations and maps of Maximum Considered Earthquake Geometric Mean (MCEG) peak ground accelerations. The MCER ground motions are also in the 2017 ASCE/SEI 41 Standard and the 2018 and 2021 editions of the International Building Code. These MCER and MCEG ground motion maps are derived from USGS National Seismic Hazard Models via the gridded values of this data release. The data files in the "Child Items" below also underlie the corresponding USGS Seismic Design Web Services. See the "Related External Resources"...
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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 2 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...
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 1.0-second spectral response acceleration (5% of critical damping) with a 50% 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 Modified Mercalli Intensity, based on peak ground acceleration, with a 2% probability of exceedance in 50 years Modified Mercalli Intensity, based on peak ground acceleration, with a 50% probability of exceedance in 50 years Data Release for the 2018 Update of the U.S. National Seismic Hazard Model Gridded earthquake ground motions for the 2015 NEHRP Recommended Seismic Provisions and 2016 ASCE/SEI 7 Standard Data Release for the 2018 Update of the U.S. National Seismic Hazard Model 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 1.0-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 2% probability of exceedance in 50 years Modified Mercalli Intensity, based on peak ground acceleration, with a 50% probability of exceedance in 50 years Gridded earthquake ground motions for the 2015 NEHRP Recommended Seismic Provisions and 2016 ASCE/SEI 7 Standard