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Each of the downloadable files below contains spectral response accelerations at 22 periods on a grid of latitudes and longitudes that cover this geographic region. See the parent item for how Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations are derived from the data in these files.
For background, please see the Parent Item. The Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration (PGA) values of the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard are calculated from the data in the downloadable files below, via the following equations: PGA = min[ PGAUH , max( PGAD84th , 0.6 ) ] for the 2009 NEHRP Recommended Seismic Provisions; PGA = min[ PGAUH , max( PGAD84th , 0.5 ) ] for the 2010 ASCE/SEI 7 Standard; where PGAUH = uniform-hazard peak ground acceleration; PGAD84th = 84th-percentile peak ground acceleration; and 0.6 or 0.5 = deterministic lower limit peak ground acceleration. These peak ground...
Categories: Data
It is well know that every earthquake can spawn others (e.g., as aftershocks), and that such triggered events can be large and damaging, as recently demonstrated by L’Aquila, Italy and Christchurch, New Zealand earthquakes. In spite of being an explicit USGS strategic-action priority (http://pubs.usgs.gov/of/2012/1088; page 32), the USGS currently lacks an automated system with which to forecast such events and official protocols for disseminating the potential implications. This capability, known as Operational Earthquake Forecasting (OEF), could provide valuable situational awareness to emergency managers, the public, and other entities interested in preparing for potentially damaging earthquakes. With the various...
Categories: Data,
Project;
Tags: Active,
All Working Groups,
California,
Earthquakes,
Natural Hazards
For designing buildings and other structures to safely resist earthquakes, the 2009 National Earthquake Hazards Reduction Program (NEHRP) Recommended Seismic Provisions and the 2010 American Society of Civil Engineers, Structural Engineering Institute (ASCE/SEI) 7 Standard contain maps of Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations, Maximum Considered Earthquake Geometric Mean (MCEG) peak ground accelerations, and long-period transition periods (TL). The MCER ground motions are also in the 2013 ASCE/SEI 41 Standard and the 2012 and 2015 editions of the International Building Code. The MCER, MCEG, and TL maps are derived from the U.S. Geological Survey (USGS) National Seismic...
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).
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.
Categories: Data;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Argentina,
Bolivia,
Brazil,
Chile,
Colombia,
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...
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.
Categories: Data;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Argentina,
Bolivia,
Brazil,
Chile,
Colombia,
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.
Categories: Data;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Argentina,
Bolivia,
Brazil,
Chile,
Colombia,
For background, please see the Parent Item. The attached files below for 8 site classes each provide risk-targeted spectral accelerations (in units of g) for a grid of latitudes and longitudes and 22 spectral periods, including 0.0 seconds for peak ground acceleration (denoted SA0P0). To compare these risk-targeted spectral accelerations with uniform-hazard counterparts analogous to those in previous editions of the AASHTO Design Specifications, corresponding risk coefficients are also provided (for all of the site classes in a single ZIP file). The risk coefficients are ratios of the risk-targeted divided by uniform-hazard spectral accelerations, with the latter for a 7% probability of being exceeded in 75 years....
Categories: Data
Each of the downloadable files below contains spectral response accelerations at 22 periods on a grid of latitudes and longitudes that cover this geographic region. See the parent item for how Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations are derived from the data in these files.
Each of the downloadable files below contains peak ground accelerations on a grid of latitudes and longitudes that cover this geographic region. See the parent item for how Maximum Considered Earthquake Geometric Mean (MCEG) peak ground accelerations are derived from the data in these files.
For background, please see the Parent Item. The attached files below for 8 site classes each provide risk-targeted spectral accelerations (in units of g) for a grid of latitudes and longitudes and 22 spectral periods, including 0.0 seconds for peak ground acceleration (denoted SA0P0). The spectral accelerations for Site Class BC and spectral periods of 0.0, 0.2, and 1.0 seconds were directly derived from the USGS seismic hazard curves released in the "Associated Item"; from these three values, the spectral accelerations for the other site classes and spectral periods were derived indirectly via the FEMA P-2078 procedures cited below, because corresponding USGS hazard curves were not yet available for Guam and the...
Categories: Data
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.
Categories: Data;
Types: Citation,
Downloadable,
GeoTIFF,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Raster,
Shapefile;
Tags: Argentina,
Bolivia,
Brazil,
Chile,
Colombia,
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...
Categories: Data;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Argentina,
Bolivia,
Brazil,
Chile,
Colombia,
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
Categories: Data;
Types: Citation,
Downloadable,
GeoTIFF,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Raster,
Shapefile;
Tags: Argentina,
Bolivia,
Brazil,
Chile,
Colombia,
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.
The Maximum Considered Earthquake Geometric Mean (MCEG) peak ground acceleration (PGA) values of the 2015 NEHRP Recommended Seismic Provisions and the 2016 ASCE/SEI 7 Standard are calculated from the data in the downloadable files below, via the following equation: PGA = min[ PGAUH , max( PGAD84th , 0.5 ) ] where PGAUH = uniform-hazard peak ground acceleration; PGAD84th = 84th-percentile peak ground acceleration. These peak ground accelerations are each for the geometric mean of two horizontal components and a site shear wave velocity (VS30) of 760 m/s. For more information, see the "Related External Resources" below. Note: The USGS Seismic Design Web Services first spatially interpolate...
Categories: Data
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.
Categories: Data;
Types: Citation,
Downloadable,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
Shapefile;
Tags: Argentina,
Bolivia,
Brazil,
Chile,
Colombia,
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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