Skip to main content
Advanced Search

Filters: Tags: Geophysics (X) > partyWithName: U.S. Geological Survey, Geologic Hazards Science Center (X)

23 results (50ms)   

View Results as: JSON ATOM CSV
thumbnail
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.
thumbnail
Subduction zones are home to the most seismically active faults on the planet. The shallow megathrust interface of subduction zones host our largest earthquakes, and are the only faults capable of M9+ ruptures. Despite these facts, our knowledge of subduction zone geometry - which likely plays a key role in determining the spatial extent and ultimately the size of subduction zone earthquakes - is incomplete. Here we calculate the three- dimensional geometries of all active global subduction zones. The resulting model - Slab2 - provides for the first time a comprehensive geometrical analysis of all known slabs in unprecedented detail. ##### This distribution includes models of three-dimensional slab geometry under...
thumbnail
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.
thumbnail
This dataset presents where, why, and how much probabilistic ground motions have changed with the 2018 update of the National Seismic Hazard Model (NSHM) for the conterminous U.S. (CONUS) vs. the 2014 NSHM. In the central and eastern U.S., hazard changes are the result of updated ground motion models (further broken down by median and epistemic uncertainty, aleatory variability, and site effects models) and gridded seismicity models. In the western U.S., hazard changes are the result of updated ground motion models in four urban areas with deep sedimentary basins and gridded seismicity models. Probabilistic ground motion changes (2% in 50 years probability of exceedance for a firm rock site, VS30 = 760 m/s, NEHRP...
thumbnail
We present high-resolution (10-cm pixel) digital surface models (DSMs) generated for the northern 16 km of the surface rupture associated with the 1983 Mw 6.9 Borah Peak earthquake. These DSMs were generated using Agisoft Photoscan (and Metashape) image-based modeling software and low-altitude aerial photographs acquired from unmanned aircraft systems and a tethered balloon. DSM files consist of GeoTIFFs with georeferencing information stored in the file headers.
thumbnail
The New Madrid Seismic Zone presents significant seismic hazard to the central and eastern United States. We mapped newly-identified coseismic ridge-spreading features, or sackungen, in the bluffs east of the Mississippi River in western Tennessee. We use this mapping dataset in an accompanying manuscript to show that sackungen form during earthquakes on the Reelfoot fault and may fail in preferred orientations. Ultimately, these data can be used to infer fault source and mechanism and improve the paleoseismic record used in hazard models.
thumbnail
A 3D temperature model is constructed in order to support the estimation of physical parameters within the USGS National Crustal Model. The crustal model is defined by a geological framework consisting of various lithologies with distinct mineral compositions. A temperature model is needed to calculate mineral density and bulk and shear modulus as a function of position within the crust. These properties control seismic velocity and impedance, which are needed to accurately estimate earthquake travel times and seismic amplitudes in earthquake hazard analyses. The temperature model is constrained by observations of surface temperature, temperature gradient, and conductivity, inferred Moho temperature and depth, and...
thumbnail
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,...
thumbnail
EXPO-CAT is a catalog of human exposure to discrete levels of shaking intensity, obtained by correlating Atlas ShakeMaps with a global population database. Combining this population exposure dataset with historical earthquake loss data provides a useful resource for calibrating loss methodologies against a systematically-derived set of ShakeMap hazard outputs. EXPO-CAT is derived from two key datasets: the PAGER-CAT earthquake catalog and the Atlas of ShakeMaps. PAGER-CAT provides accurate earthquake source information necessary to compute reliable ShakeMaps in the Atlas. It also contributes loss information (i.e., number of deaths and injuries) from historical events. Using historical earthquakes in the Atlas and...
thumbnail
The U.S. Geological Survey National Crustal Model (NCM) is being developed to include spatially varying estimates of site response in seismic hazard assessments. Primary outputs of the NCM are continuous velocity and density profiles from the Earth’s surface to the mantle transition zone at 410 km depth for each location on a 1-kilometer grid across the conterminous United States. Datasets used to produce the NCM may have a resolution of better than 1 km near the Earth’s surface in some regions, but, with increasing depth, NCM resolution decreases to 10’s to 100’s of km in the mantle. Basic subsurface information is provided by the NCM geologic framework (NCMGF), thermal model, and petrologic and mineral physics...
thumbnail
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...
thumbnail
This dataset consists of over 800 field observations of ground failure (landslides, lateral spreading, and liquefaction) and other damage triggered by the 2019-2020 Puerto Rico earthquake sequence. The sequence started with a M4.7 earthquake on 28 December 2019, followed by many more earthquakes, including 15 larger than M5 (as of 7 July 2020). The M6.4 mainshock, which is thought to have triggered much of the observed ground failure, occurred on 7 January 2020. Most field reconnaissance efforts documented here took place as soon as possible after the mainshock, from 12-18 January 2020, to attempt to capture ephemeral data before evidence was destroyed by natural forces or repairs, but observations continued to...
thumbnail
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...
thumbnail
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.
thumbnail
The ANSS Backbone Network is based on the core of the original US National Seismic Network. In partnership with the National Science Foundation, the USGS worked with the Earthscope program (through the USArray project and IRIS) in 2004-2006 to upgrade and install new backbone stations. This effort was completed in September 2006, with 15 new stations installed and 20 existing stations upgraded. Today, the ANSS Backbone consists of nearly 100 stations in the United States, many of them contributed by partner networks and organizations.
thumbnail
A 3D geologic framework is presented here as part of the U.S. Geological Survey National Crustal Model for the western United States, which will be used to improve seismic hazard assessment. The framework is based on 1:250,000 to 1:1,000,000-scale state geologic maps and depths of multiple subsurface unit boundaries. The geology at or near the Earth’s surface is based on published maps with modifications to remove discontinuities across state borders. Extrapolation of rock type and age in the subsurface is achieved by iterative stripping of units of a given age, nearest neighbor interpolation of the remaining units, and constraints on basement geology. The subsurface depth of the interfaces between units is determined...
thumbnail
The 2016 M5.8 Pawnee, Oklahoma earthquake is the largest earthquake to have been induced by wastewater disposal. We infer the coseismic slip history from analysis of apparent source time functions and inversion of regional and teleseismic P-waveforms, using aftershocks as empirical Green’s functions. The earthquake nucleated on the shallow part of the fault, initially rupturing towards the surface, followed shortly thereafter by slip deeper on the fault. Deeper slip occurred below the aftershocks and at greater depths than most induced seismicity in the region, suggesting that small- to moderate-sized earthquakes may not occur on deeper parts of faults in Oklahoma because they are further from failure than shallower...
thumbnail
PAGER (Prompt Assessment of Global Earthquakes for Response) is an automated system that estimates the impact of significant earthquakes around the world, informing emergency responders, government and aid agencies, and the media of the scope of the potential disaster. PAGER rapidly assesses earthquake impacts by comparing the population exposed to each estimated shaking intensity level with models of economic and fatality losses based on past earthquakes in each country or region of the world. PAGER sends out alerts based on the estimated range of fatalities and economic losses.
thumbnail
PAGER-CAT incorporates eight global earthquake catalogs and additional auxiliary data to provide comprehensive information for hypocentral locations, magnitudes, and human fatalities, focal mechanisms, the country of origin or the distance to the nearest landmass, local time and day of week, presence of secondary effects (e.g., tsunami, landslide, fire, or liquefaction) and deaths caused by these effects, the number of buildings damaged or destroyed, and the number of people injured or left homeless. The first version of the catalog contains more than 140 fields in which detailed event information can be recorded and currently includes events from 1900 through December 2007, with emphasis on earthquakes since 1973.
thumbnail
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...
map background search result map search result map An Updated Vs30 Map for California with Geologic and Topographic Constraints (ver. 2.0, July 2022) Data Release for Additional Period and Site Class Maps for the 2014 National Seismic Hazard Model for the Conterminous United States Data Set S1 for "Coseismic Sackungen in the New Madrid Seismic Zone, USA" Data for Rupture Model of the 2016 M5.8 Pawnee, Oklahoma Earthquake Digital Surface Models for the northern 16 km of the 1983 Borah Peak earthquake rupture, northern Lost River fault zone (Idaho, USA) 3D Geologic Framework for use with the U.S. Geological Survey National Crustal Model, Phase 1: Western United States Grids in support of the U.S. Geological Survey Thermal Model for Seismic Hazard Studies Calibration Coefficients for the U.S. Geological Survey National Crustal Model and Depth to Water Table Field observations of ground failure triggered by the 2020 Puerto Rico earthquake sequence Data Release for the 2018 Update of the U.S. National Seismic Hazard Model: Where, Why, and How Much Probabilistic Ground Motion Maps Changed Digital Surface Models for the northern 16 km of the 1983 Borah Peak earthquake rupture, northern Lost River fault zone (Idaho, USA) Data Set S1 for "Coseismic Sackungen in the New Madrid Seismic Zone, USA" Field observations of ground failure triggered by the 2020 Puerto Rico earthquake sequence Data for Rupture Model of the 2016 M5.8 Pawnee, Oklahoma Earthquake An Updated Vs30 Map for California with Geologic and Topographic Constraints (ver. 2.0, July 2022) 3D Geologic Framework for use with the U.S. Geological Survey National Crustal Model, Phase 1: Western United States Data Release for Additional Period and Site Class Maps for the 2014 National Seismic Hazard Model for the Conterminous United States Data Release for the 2018 Update of the U.S. National Seismic Hazard Model: Where, Why, and How Much Probabilistic Ground Motion Maps Changed Calibration Coefficients for the U.S. Geological Survey National Crustal Model and Depth to Water Table Grids in support of the U.S. Geological Survey Thermal Model for Seismic Hazard Studies