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The 2002 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. This update of the maps incorporates new findings on earthquake ground shaking, faults, seismicity, and geodesy. The resulting maps are derived from seismic hazard curves calculated on a grid of sites across the United States that describe the frequency of exceeding a set of ground motions.
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The U.S. Geological Survey’s National Seismic Hazard Map Program publishes a number of products and tools designed to provide details of earthquake shaking hazards and help engineers meet modern seismic design provisions for the construction of buildings, bridges, highways, and utilities that are better able to withstand earthquakes, not only saving lives but also enabling critical activities to continue with less disruption.
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The significant rise in seismicity rates in Oklahoma and Kansas (OK–KS) in the last decade has led to an increased interest in studying induced earthquakes. Although additional instruments have been deployed in the region, there are still relatively few recordings at the distances (<20 km) and magnitudes (M4+) most relevant to earthquake hazard. In contrast, the USGS Did You Feel It? (DYFI) system has collected more than 200,000 observations during this period with 22,000+ observations at distances less than 20 km. This dataset has already been used to study the unique characteristics of induced earthquakes, to evaluate the extent of felt area, shaking, and damage, to compare intensity and ground motion metrics,...
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The 2014 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. The updated maps represent an assessment of the best available science in earthquake hazards and incorporate new findings on earthquake ground shaking, faults, seismicity, and geodesy. The USGS National Seismic Hazard Mapping Project developed these maps by incorporating information on potential earthquakes and associated ground shaking obtained from interaction in science and engineering workshops involving hundreds of participants,...
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Earthquake stress drop is a critical parameter for estimating seismic hazard. This parameter can have a strong effect on ground motion amplitudes above ~1Hz and is especially important in Oklahoma and Kansas where earthquake rates have increased sharply since 2008. We estimate stress drops for 1121 earthquakes greater than ~M3 in and near the conterminous United States using spectral ratios between collocated events at given stations. We find that the average stress drop for the few eastern United States (EUS, 26–340 Bars) tectonic main shocks studied, which tend to be deeper thrusting events with few foreshocks and aftershocks, is about three times greater than tectonic main shocks in the western United States...
The significant rise in seismicity rates in Oklahoma and Kansas (OK–KS) in the last decade has led to an increased interest in studying induced earthquakes. Although additional instruments have been deployed in the region, there are still relatively few recordings at the distances (<20 km) and magnitudes (M4+) most relevant to earthquake hazard. In contrast, the USGS Did You Feel It? (DYFI) system has collected more than 200,000 observations during this period with 22,000+ observations at distances less than 20 km. This dataset has already been used to study the unique characteristics of induced earthquakes, to evaluate the extent of felt area, shaking, and damage, to compare intensity and ground motion metrics,...
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The USGS is offering earthquake alerts via two twitter accounts: @USGSted and @USGSBigQuakes. On average, @USGSted and @USGSBigQuakes will produce about one tweet per day, however, aftershocks following major earthquakes can greatly increase this number. Users interested in custom alerts based on specific geographic regions and magnitude thresholds should sign up for e-mail alerts distributed by our Earthquake Notification Service (ENS).
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The 2008 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. This update of the maps incorporates new findings on earthquake ground shaking, faults, seismicity, and geodesy. The resulting maps are derived from seismic hazard curves calculated on a grid of sites across the United States that describe the frequency of exceeding a set of ground motions. The USGS National Seismic Hazard Mapping Project developed these maps by incorporating information on potential earthquakes and associated ground...
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We used matched filter detection and multiple-event relocation techniques to characterize the spatiotemporal evolution of the sequence. Our analysis is from the 14 closest seismic stations to the earthquake sequence, which included seven permanent stations from the Montana Regional Seismic Network, one permanent station from the ANSS backbone network and three temporary seismic stations deployed by the USGS within four days after the mainshock. A catalog of 685 well-located earthquakes larger than M 1 occurring Between 5 July and 15 October 2017 were relocated using a hypocentroid decomposition (HD) multiple-event relocation approach. The resulting dataset had an average epicentral and depth uncertainties (90% confidence)...
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This data release provides a map of the time-averaged shear-wave velocity in the upper 30 m (Vs30) for California using the method described by Thompson and others (2014). There are two adjustments to the algorithm described by Thompson and others (2014), which is built on the geology-based Vs30 map by Wills and Clahan (2006). In this data release, we use the Wills and others (2015) updated geology-based Vs30 map. The second change is that we have adjusted the kriging procedure so that measured Vs30 values do not affect the predictions across distinctly different geologic units. July 2022 Update (ver. 2.0) Resolution is now 3 arcseconds instead of 7.5 arcseconds Fixed a code error that prevented some of the Vs30...
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The Earthquake Notification Service (ENS) is a free service that sends you automated notifications to your email or cell phone when earthquakes happen.


    map background search result map search result map Influence of Lithostatic Stress on Earthquake Stress Drops in North America An Updated Vs30 Map for California with Geologic and Topographic Constraints (ver. 2.0, July 2022) Spatiotemporal Analysis of the Foreshock-Mainshock-Aftershock Sequence of the 6 July 2017 M5.8 Lincoln, Montana, Earthquake - Data Release Generalized Tectonic Map of Bangladesh (tect8bg) Spatiotemporal Analysis of the Foreshock-Mainshock-Aftershock Sequence of the 6 July 2017 M5.8 Lincoln, Montana, Earthquake - Data Release Generalized Tectonic Map of Bangladesh (tect8bg) An Updated Vs30 Map for California with Geologic and Topographic Constraints (ver. 2.0, July 2022) Influence of Lithostatic Stress on Earthquake Stress Drops in North America