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ShakeMap is a product of the USGS Earthquake Hazards Program in conjunction with the regional seismic networks. ShakeMaps provide near-real-time maps of ground motion and shaking intensity following significant earthquakes. These maps are used by federal, state, and local organizations, both public and private, for post-earthquake response and recovery, public and scientific information, as well as for preparedness exercises and disaster planning.
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A scenario represents one realization of a potential future earthquake by assuming a particular magnitude, location, and fault-rupture geometry and estimating shaking using a variety of strategies. In planning and coordinating emergency response, utilities, local government, and other organizations are best served by conducting training exercises based on realistic earthquake situations—ones similar to those they are most likely to face. ShakeMap Scenario earthquakes can fill this role. They can also be used to examine exposure of structures, lifelines, utilities, and transportation corridors to specified potential earthquakes. A ShakeMap earthquake scenario is a predictive ShakeMap with an assumed magnitude and...
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New active-source shallow seismic (shear-wave and acoustic-wave) measurements were obtained at 18 prioritized seismic monitoring station locations in the north San Francisco Bay area to measure site-specific ground motion amplification effects, soil depth, depth to bedrock (Z1.0 Vs=1 km/s), calculate site specific velocity-depth profiles and Vs30, and develop NEHRP site classifications for each location. This study was led by Principal Investigators Jamey Turner, Cooper Brossy, and Daniel O’Connell and field data were acquired by Glendon Adams and Lincoln Steele. Seismic monitoring sites that recorded high PGA values during the M6.0 Napa earthquake, proximal to higher population densities, and sites recommended...
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The NEIC global earthquake bulletin is called the Preliminary Determination of Epicenters or PDE, and is one of many discrete products in the ANSS Comprehensive Catalog (ComCat). We use the word "Preliminary" for our final bulletin because the Bulletin of the International Seismological Centre is considered to be the final global archive of parametric earthquake data, in other words phase arrival (“pick”) times and amplitudes.
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Compiled Vs30 measurements obtained by studies funded by the U.S. Geological Survey (USGS) and other governmental agencies. Thus far, there are 2,997 sites in the United States, along with metadata for each measurement from government-sponsored reports, Web sites, and scientific and engineering journals. Most of the data originated from publications directly reporting the work of field investigators. A small subset (less than 20 percent) of Vs30 values was previously compiled by the USGS and other research institutions. Whenever possible, Vs30 originating from these earlier compilations were crosschecked against published reports. Both downhole and surface-based Vs30 estimates are represented. Most of the VS30 data...
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About 280 kilometers of multichannel (common-depth-point) seismic reflection profiles were obtained in the central Mississippi River Valley by Geophysical Service Inc. and Western Geophysical Company under contracts with the U.S. Geological Survey. The specific area of the profiles is southeastern Missouri, northeastern Arkansas, and northwestern Tennessee. Geologically, the area is located in the northern part of the Mississippi Embayment.
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The data for this release is an ASCII file containing grid points of Cascadia P- and S-wave velocity models. The model volume was developed to include the Cascadia subduction zone for purposes of ground motion simulation. The description of the model and background of its development is provided in the associated Open-File Report. The grid points are given in Universal Transverse Mercator (UTM) Zone 10 North coordinates for East and North locations, and the grid point depths are given in meters below mean sea level. Grid point spacing is 500 meters in each ordinal direction. The model region extends approximately from 40.2°N to 50°N latitude, and approximately from 122°W to 129°W longitude. The maximum depth of...
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This data release includes geodetic time series from high-rate GPS instruments recording 4 earthquakes co-seismically in the near-field – the 2010 Maule, Chile earthquake; the 2012 Nicoya, Costa Rica earthquake; the 2014 Iquique, Chile earthquake; and the 2015 Gorkha, Nepal earthquake. For each earthquake, data (sac files, 1 Hz sampling, ~2-3 minutes around the earthquake origin time) are included in a separate folder. Each sac file provides a time series of ground displacement from the earthquake as recorded at that station. The location of each station is listed in the relevant earthquake file in the “_station_info” folder.
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The dataset contains broadband synthetic ground motion records for three events: 1) 1994 M6.7 Northridge, CA, 2) 1989 M7.0 Loma Prieta, CA, and 3) 1999 M7.5 Izmit, Turkey. For each event, 1D synthetic earthquake ground motion time histories are provided, based on four different methodologies: 1) Frankel, A. (2009). A constant stress-drop model for producing broadband synthetic seismograms: comparison with the next generation attenuation relations, Bull. Seism. Soc. Am. V.99, 664-680. 2) Hartzell, S., M. Guatteri, P. Martin Mai, P. Liu, and M. Fisk (2005). Calculation of broadband time histories of ground motion, part II: kinematic and dynamic modeling using theoretical Green’s functions and comparison with the 1994...
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The Global Vs30 Server allows a user to select from a map or input a rectangular region of interest. It then provides (optionally) a Vs30 grid in ASCII or GMT grid format, and a JPEG Vs30 map. Wald et al. (2004) first, and Wald and Allen (BSSA, 2007, in press), more fully, describe a methodology for deriving maps of seismic site conditions using topographic slope as a proxy. Vs30 measurements (the average shear-velocity down to 30 m) are correlated against topographic slope to develop two sets of coefficients for deriving Vs30: one for active tectonic regions that possess dynamic topographic relief, and one for stable continental regions where changes in topography are more subdued.
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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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OpenSHA is an effort to develop object-oriented, web- & GUI-enabled, open-source, and freely available code for conducting Seismic Hazard Analyses (SHA). Our goal is to provide a framework where any arbitrarily complex (e.g., physics based) earthquake-rupture forecast, ground-motion, or engineering-response model can “plug in” for analysis without having to change what’s being plugged into.
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A Finite Fault is a modeled representation of the spatial extent, amplitude and duration of fault rupture (slip) of an earthquake, and is generated via the inversion of teleseismic body waveforms and long period surface waves. It may indicate that a location of major fault-slip and source of seismic energy has occurred at a significant distance from the earthquake epicenter, which is the location on the fault where the earthquake rupture nucleated. For many earthquakes, the preferred model represents the distribution of slip on one of the two alternative fault-planes that are implied by the earthquake moment-tensor. For some earthquakes, the seismographic data are fit equally well by models involving slip on either...
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The DYFI system collects observations from people who felt an earthquake and then maps out the extent of shaking and damage they reported. The ComCat online Search interface allows users to select query criteria that return events with DYFI data and products.
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 ANSS Comprehensive Catalog (ComCat) contains earthquake source parameters and other products produced by contributing seismic networks. Important digital catalogs of earthquake source parameters (e.g. Centennial Catalog, Global Centroid Moment Tensor Catalog) are loaded into ComCat. New and updated data are added to the catalog dynamically as sources publish or update products. Access to the ComCat is via the online search page, on which a user can select a wide variety of criteria to locate earthquake events of interest. Source Parameters: -amplitude - hypocenter - magnitude - phase data - finite fault - focal mechanism - moment tensor - tectonic summary - regional information Products: - Did You Feel It? -...
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The USGS collaborates with organizations (such as the Building Seismic Safety Council) that develop model building and bridge design codes to make seismic design parameter values available to engineers. The design code developers first decide how USGS earthquake hazard information should be applied in design practice. Then the USGS calculates gridded values of seismic design parameters based on USGS hazard values in accordance with design code procedures. The U.S. Seismic Design Maps application provides seismic design parameter values from the following design code editions: 2013 ASCE/SEI 41, 2012/09/06 International Building Code, 2010/05 ASCE/SEI 7 Standard, 2009/03 NEHRP Recommended Seismic Provisions, 2009...
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This tool is used to calculate risk-targeted ground motion values from probabilistic seismic hazard curves in accordance with the site-specific ground motion procedures defined in “Method 2” of 2010 ASCE 7 Standard Section 21.2.1.2.
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The Quaternary Fault and Fold Database contains the results of thousands of scientific assessments of faults and associated folds in the United States that demonstrate geologic evidence for coseismic surface deformation in the Quaternary (the past 1,600,000 years). The Quaternary Fault and Fold Database includes information on the age of the most recent coseismic surface deformation, relative rates of activity, fault geometry, sense of movement, and citations of pertinent literature. Much of the information in the database is based on paleoseismology, which is the geologic study of prehistoric earthquakes. Paleoseismology combines well-established geologic practices such as trenching with archeological-style analysis...
map background search result map search result map Seismic Reflection Profiles in the Northern Mississippi Embayment Quaternary Fault and Fold Database of the United States Data for P- and S-wave Seismic Velocity Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion simulations- Update for Open-File Report 2007-1348 Seismic Reflection Profiles in the Northern Mississippi Embayment Data for P- and S-wave Seismic Velocity Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion simulations- Update for Open-File Report 2007-1348 Quaternary Fault and Fold Database of the United States