The 2008 Wells, Nevada Earthquake Sequence: Source Constraints using Calibrated Multiple Event Relocation and InSAR

For designing buildings and other structures to safely resist earthquakes, the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard contain maps of Uniform Hazard response accelerations, risk coefficients, 84th-percentile spectral accelerations, and Risk-Targeted Maximum Considered Earthquake (MCER) spectral response accelerations, all at spectral periods of 0.2-second and 1.0-second. The spectral accelerations are for the direction of maximum horizontal response and a site shear wave velocity (VS30) of 760 m/s, in units of the percent g, the acceleration of gravity. For more information, see Chapters 11, 21, and 22 of the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard.

This dataset contains the supplemental information for the article "Oklahoma experiences largest earthquake during ongoing regional wastewater injection hazard mitigation efforts" published in Geophysical Research Letters. Included is a table of relocated earthquake hypocenters and the velocity model used in the event relocations. These locations form the basis of the analysis presented in the article.

This dataset contains the supplemental information for the article "Oklahoma experiences largest earthquake during ongoing regional wastewater injection hazard mitigation efforts" published in Geophysical Research Letters. Included is a table of relocated earthquake hypocenters and the velocity model used in the event relocations. These locations form the basis of the analysis presented in the article.

Seismicity catalogs, gridded seismic hazard curve data, gridded ground motion data, and mapped gridded ground motion values are available for the 2008 National Seismic Hazard Model for the Conterminous U.S. (1) Seismicity catalogs are available for the western U.S. (in Mw) and central and eastern U.S. (in mb). (2) Gridded (0.05 degree by 0.05 degree) ground motion values and hazard maps are available for peak ground acceleration (PGA) and 0.1, 0.2, 0.3, 0.5, 1.0, and 2.0 second spectral acceleration (SA) at probability levels of 2% in 50 years (annual probability of 0.000404), 5% in 50 years (annual probability of 0.001026), and 10% in 50 years (annual probability of 0.0021), assuming firm rock soil conditions at 760 m/s, for the conterminous U.S. (US). Additional periods (0.75s, 3s, 4s, and 5s) are available for the western U.S. (WUS). Data was derived from the probabilistic seismic hazard curves. (3) Gridded (0.1 degree by 0.1 degree) ground motion values and hazard maps are available for peak ground acceleration (PGA) and 0.1, 0.2, 0.3, 0.5, 1.0, and 2.0 second spectral acceleration (SA) at probability levels of 2% in 50 years (annual probability of 0.000404), 5% in 50 years (annual probability of 0.001026), and 10% in 50 years (annual probability of 0.0021), assuming hard rock site conditions at 2,000 m/s, for the central and eastern U.S. (CEUS). Data was derived from the probabilistic seismic hazard curves. (4) Gridded (0.05 degree by 0.05 degree) ground motion values and hazard maps are available for peak ground acceleration (PGA) and 0.1, 0.2, 0.3, 0.5, 0.75s, 1.0, 2.0, 3.0, 4.0, and 5.0 second spectral acceleration (SA) at probability levels of 2% in 50 years (annual probability of 0.000404), 5% in 50 years (annual probability of 0.001026), and 10% in 50 years (annual probability of 0.0021), for VS30 values of 1,150 m/s, 537 m/s, 360 m/s, 259 m/s, and 180 m/s, for the western U.S. (WUS). Data was derived from the probabilistic seismic hazard curves. Development of the 2008 National Seismic Hazard Model for the Conterminous U.S. is documented in the USGS Open-File Report 2008-1128 (https://doi.org/10.3133/ofr20081128). This dataset is considered a legacy dataset. The original dataset was uploaded to the USGS website at the time of publication of the seismic hazard model (2008) but was later moved over the the USGS ScienceBase Catalog (2019). The original dataset was assumed to be complete and accurate, but may contain inconsistencies when compared to more recent, actively maintained datasets.

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 of site response in seismic hazard analysis, this model can benefit other fields of research.

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 of site response in seismic hazard analysis, this model can benefit other fields of research.

The 2014 update of the U.S. Geological Survey (USGS) National Seismic Hazard Model (NSHM) for the conterminous United States (2014 NSHM; Petersen and others, 2014; https://pubs.usgs.gov/of/2008/1128/) included probabilistic ground motion maps for 2 percent and 10 percent probabilities of exceedance in 50 years, derived from seismic hazard curves for peak ground acceleration (PGA) and 0.2 and 1.0 second spectral accelerations (SAs) with 5 percent damping for the National Earthquake Hazards Reduction Program (NEHRP) site class boundary B/C (time-averaged shear wave velocity in the upper 30 meters [VS30]=760 meters per second [m/s]). This data release provides 0.1 degree by 0.1 degree gridded seismic hazard curves, 0.1 degree by 0.1 degree gridded probabilistic ground motions, and seismic hazard maps calculated for additional periods and additional uniform NEHRP site classes using the 2014 NSHM. For both the central and eastern U.S. (CEUS) and western U.S. (WUS), data and maps are provided for PGA, 0.1, 0.2, 0.3, 0.5, 1.0, and 2.0 second SAs with 5% damping for the NEHRP site class boundary B/C for 2, 5, and 10% probabilities of exceedance in 50 years. The WUS additionally includes data and maps for 0.75, 3.0, 4.0, and 5.0 SAs. The use of region-specific suites of weighted ground motion models (GMMs) in the 2014 NSHM precluded the calculation of ground motions for a uniform set of periods and site classes for the conterminous U.S. At the time of development of the 2014 NSHM, there was no consensus in the CEUS on an appropriate site-amplification model to use, therefore, we calculated hazard curves and maps for NEHRP Site Class A (VS30 = 2000 m/s), for which most stable continental GMMs were original developed, based on simulations for hard rock conditions. In the WUS, however, the GMMs allow amplification based on site class (defined by VS30), so we calculated hazard curves and maps for NEHRP site classes B (VS30 = 1080 m/s), C (VS30 = 530 m/s), D (VS30 = 260 m/s), and E (VS30 = 150 m/s) and site class boundaries A/B (VS30 = 1500 m/s), B/C (VS30 = 760 m/s), C/D (VS30 = 365 m/s), and D/E (VS30 = 185 m/s). Further explanation about how the data and maps were generated can be found in the accompanying U.S. Geological Survey Open-File Report 2018-1111 (https://doi.org/10.3133/ofr20181111). First Posted - July 18, 2018 Revised - February 20, 2019 (ver. 1.1)

Epicenters of known M≥5 earthquakes from 1769 to 2016 are shown for California and a 100 km area bordering the state. Earthquakes are grouped by: M = 5-6; M = 6-7; M = 7+.

This Data Release contains preliminary versions of two related databases: 1) A fault sections database (“NSHM23_FSD_v2”), which depicts the geometry of faults capable of hosting independent earthquakes, and 2) An earthquake geology site information database (“NSHM23_EQGeoDB_v2”), which contains fault slip-rate constraints at points. These databases were prepared in anticipation of updates to the National Seismic Hazard Model (NSHM) 2023. Fault-specific geologic parameters for the NSHM have not been updated since the 2014 NSHM release. The datasets include the states of Washington, Oregon, California, Idaho, Nevada, Arizona, Montana, Wyoming, Colorado, New Mexico and Texas. Datasets containing fault information for Alaska and the Central and Eastern United States will be the subject of future efforts. These databases are provided as geospatial data (e.g., .SHP and .GeoJSON file formats) and tables (.CSV or .TXT format). Please note: these databases are updated as of February 2022 (version 2), which supersede the databases release in January 2021 (version 1).