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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.
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: EHP,
Earth,
Earthquake Hazards Program,
GHSC,
Geologic Hazards Science Center,
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...
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...
Types: Citation;
Tags: ANSS,
Advanced National Seismic System,
ComCat,
Comprehensive Earthquake Catalog,
Earth,
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.
Types: Citation;
Tags: ANSS,
Advanced National Seismic System,
ComCat,
Comprehensive Earthquake Catalog,
DYFI,
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...
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Brune stress drop,
Earthquake Hazards Program,
GHSC,
Geologic Hazards Science Center,
Geophysics,
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,...
Types: Citation;
Tags: DYFI,
Did You Feel It,
Earthquake Hazards Program,
GHSC,
Geologic Hazards Science Center,
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.
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: EHP,
Earth,
Earthquake Hazards Program,
GHSC,
Geologic Hazards Science Center,
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.
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: EHP,
Earth,
Earthquake Hazards Program,
GHSC,
Geologic Hazards Science Center,
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).
Types: Citation;
Tags: Earth,
Earthquake Hazards Program,
GHSC,
Geologic Hazards Science Center,
USGS,
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? -...
Types: Citation;
Tags: ANSS,
Advanced National Seismic System,
ComCat,
Comprehensive Earthquake Catalog,
DYFI,
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...
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.
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...
This data release contains data sets associated with the 2023 50-State National Seismic Hazard Model Update. The 2023 50-State National Seimsic Hazard Model (NSHM) Update includes an update to the NSHMs for the conterminous U.S (CONUS, last updated in 2018), Alaska (AK, last updated in 2007), and Hawaii (last updated in 2001). Data sets include inputs like seismicity catalogs used as input to the smoothed seismicity model and updated induced seismicity zone polygons in the central and eastern U.S., as well as outputs like hazard curves and uniform-hazard ground motion values. Plots of selected data sets are also included. The data sets provided here are primarily for the 2023 CONUS NHSM and 2023 AK NSHM. Additional...
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Alaska,
Conterminous United States,
Earthquake,
Hawaii,
Hazard,
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.
The dataset for this investigation consists of microtremor array data collected at 11 sites in the Seattle basin, Washington State. Ten of the arrays consisted of seven Nanometrics Trillium Compact broadband sensors deployed in asymmetric nested triangles (sites ST01, BA02, SP04, LF05, UW06, SN07, RD08, EL09, CH10, and KG11) that recorded for up to six hours. The eleventh array, at site NW03, was supplemented with a smaller triangular array that recorded for about 1 hour before redeployment to a larger array. The inter-sensor distances varied from about 173 m to 2000 m. The data were recorded on Reftek RT-130 data loggers and converted to SAC binary format for archival. All three components were recorded from each...
The datasets for this investigation consist of microtremor array data collected at sites in San Jose, California, Pleasanton, California, and synthetic microtremor array data created as part of a blind shear-wave velocity modeling study as part of the Third International Symposium on the Effects of Surface Geology on Seismic Motion (ESG2006), Grenoble, France, 30 August - 1 September 2006. The data from site STGA in San Jose, consisting of seven sensors used in the paper, are available from the Incorporated Research Institutions for Seismology (IRIS) through a request form at http://ds.iris.edu/ds/nodes/dmc/forms/assembled-data/?dataset_report_number=04-016. An associated report for these data available at http://ds.iris.edu/data/reports/2004/04-016/04-016.pdf....
Earthquake-based models of slab geometry are limited by the distribution of earthquakes within a subducting slab, which is often heterogeneous. The fast seismic velocity signature of slabs in tomography studies is independent of the distribution of earthquakes within the slab, providing a critical constraint on slab geometry when earthquakes are absent. In order to utilize this constraint, researchers typically hand-contour images of subducting slabs in tomography models, leading to a subjective final slab model. With this paper, we present an automated procedure for extracting slab geometry from teleseismic tomography volumes that limits this subjectivity and provides constraints on the structure of aseismic segments...
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...
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: EHP,
Earthquake Hazards Program,
GHSC,
Geologic Hazards Science Center,
Geophysics,
Significant uncertainty remains in how and where crustal shortening occurs throughout the eastern Cascade Range in Washington State. Using lidar imagery, we identified a ~5 km long lineament in Swakane canyon near Wenatchee, roughly coincident with a strand of the Entiat fault. Topographic profiles across the lineament reveal a southwest-side-up break in slope with an average of ~3 m of vertical separation of the hillslope surface. We consider a range of possible origins for this feature, including differential erosion across a fault-line scarp, slope failure (sackung or landslide), and surface deformation across an active fault strand. Based on trenching, radiocarbon and luminescence dating, and ground penetrating...
Categories: Data;
Types: Citation,
Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Cascades, Washington,
EHP,
Earthquake Hazards Program,
GHSC,
Geologic Hazards Science Center,
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