2018 Short-term Induced Seismicity Model
The USGS has produced the 2018 one-year probabilistic seismic hazard forecast for the central and eastern United States from induced and natural earthquakes. For consistency, the updated 2018 forecast is developed using the same probabilistic seismicity-based methodology as applied in the two previous forecasts.
Rates of earthquakes across the U.S. M ≥ 3.0 grew rapidly between 2008 and 2015 but have steadily declined over the past three years, especially in areas of Oklahoma and southern Kansas where fluid injection has decreased. The seismicity pattern in 2017 was complex with earthquakes more spatially dispersed than in previous years. Some areas of west-central Oklahoma experienced increased activity rates where industrial activity increased. Earthquake rates in Oklahoma (429 earthquakes of M ≥ 3 and 4 M ≥ 4), Raton Basin (Colorado/New Mexico border, 6 earthquakes M ≥ 3), and the New Madrid seismic zone (11 earthquakes M ≥ 3) continue to be higher than historical levels. Almost all of these earthquakes occurred within the highest hazard regions of the 2017 forecast.
Even though rates declined over the past three years, the short-term hazard for damaging ground shaking across much of Oklahoma remains at high levels due to continuing high rates of smaller earthquakes that are still hundreds of times higher than at any time in the State’s history. These short-term hazard levels are similar to active regions in California. During 2017, M ≥ 3 earthquakes also occurred in or near Ohio, West Virginia, Missouri, Kentucky, Tennessee, Arkansas, Illinois, Oklahoma, Kansas, Colorado, New Mexico, Utah, and Wyoming.
2017 Short-term Induced Seismicity Model
The U.S Geological Survey (USGS) has produced a one-year 2017 seismic hazard forecast for the central and eastern United States from induced and natural earthquakes that updates the 2016 one-year forecast; this map is intended to provide information to the public and to facilitate the development of induced seismicity forecasting models, methods, and data. The 2017 hazard model applies the same methodology and input logic tree as the 2016 forecast, but with an updated earthquake catalog.
The 2016 forecast indicated high seismic hazard (greater than 1% probability of potentially damaging ground shaking in one-year) in five focus areas: Oklahoma-Kansas, the Raton Basin (Colorado/New Mexico border), north Texas, north Arkansas, and the New Madrid seismic zone. During 2016, several damaging induced earthquakes occurred in Oklahoma within the highest hazard region of the 2016 forecast; all of the 21 magnitude (M) ≥ 4 and three M ≥ 5 earthquakes occurred within the highest hazard area in the 2016 forecast. Outside the Oklahoma-Kansas focus area, two earthquakes with M ≥ 4 occurred near Trinidad, Colorado (in the Raton Basin focus area), but no earthquakes with M ≥ 2.7 were observed in the north Texas or north Arkansas focus areas. Several observations of damaging ground shaking levels were also recorded in the highest hazard region of Oklahoma. The 2017 forecasted seismic rates are lower in regions of induced activity due to lower rates of earthquakes in 2016 compared to 2015, which may be related to decreased wastewater injection, caused by regulatory actions or by a decrease in unconventional oil and gas production. Nevertheless, the 2017 forecasted hazard is still significantly elevated in Oklahoma compared to the hazard calculated from seismicity before 2009.
2016 Short-term Induced Seismicity Model
The U.S. Geological Survey (USGS) has produced a 1-year seismic hazard forecast for 2016 for the Central and Eastern United States (CEUS) that includes contributions from both induced and natural earthquakes. The model assumes that earthquake rates calculated from several different time windows will remain relatively stationary and can be used to forecast earthquake hazard and damage intensity for the year 2016. This assessment is the first step in developing an operational earthquake forecast for the CEUS, and the analysis could be revised with updated seismicity and model parameters. Consensus input models consider alternative earthquake catalog durations, smoothing parameters, maximum magnitudes, and ground motion estimates, and represent uncertainties in earthquake occurrence and diversity of opinion in the science community.
Ground shaking seismic hazard for 1-percent probability of exceedance in 1 year reaches 0.6 g (as a fraction of standard gravity [g]) in northern Oklahoma and southern Kansas, and about 0.2 g in the Raton Basin of Colorado and New Mexico, in central Arkansas, and in north-central Texas near Dallas. Near some areas of active induced earthquakes, hazard is higher than in the 2014 USGS National Seismic Hazard Model (NHSM) by more than a factor of 3; the 2014 NHSM did not consider induced earthquakes. In some areas, previously observed induced earthquakes have stopped, so the seismic hazard reverts back to the 2014 NSHM. Increased seismic activity, whether defined as induced or natural, produces high hazard. Conversion of ground shaking to seismic intensity indicates that some places in Oklahoma, Kansas, Colorado, New Mexico, Texas, and Arkansas may experience damage if the induced seismicity continues unabated. The chance of having Modified Mercalli Intensity (MMI) VI or greater (damaging earthquake shaking) is 5–12 percent per year in north-central Oklahoma and southern Kansas, similar to the chance of damage caused by natural earthquakes at sites in parts of California.
- 2016 One-Year Seismic Hazard Model from Induced and Natural Earthquakes
- Incorporating Induced Seismicity in the 2014 United States National Seismic Hazard Model—Results of 2014 Workshop and Sensitivity Studies (USGS OFR 2015-1070)
2014 Long-term Model
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, review by several science organizations and State surveys, and advice from expert panels and a Steering Committee. The new probabilistic hazard maps represent an update of the seismic hazard maps; previous versions were developed by Petersen and others (2008) and Frankel and others (2002), using the methodology developed Frankel and others (1996). Algermissen and Perkins (1976) published the first probabilistic seismic hazard map of the United States which was updated in Algermissen and others (1990).
The National Seismic Hazard Maps are derived from seismic hazard curves calculated on a grid of sites across the United States that describe the annual frequency of exceeding a set of ground motions. Data and maps from the 2014 U.S. Geological Survey National Seismic Hazard Mapping Project are available for download below. Maps for available periods (0.2 s, 1 s, PGA) and specified annual frequencies of exceedance can be calculated from the hazard curves. Figures depict probabilistic ground motions with a 2 percent probability of exceedance. Spectral accelerations are calculated for 5 percent damped linear elastic oscillators. All ground motions are calculated for site conditions with Vs30=760 m/s, corresponding to NEHRP B/C site class boundary.
- Simplified 2014 Hazard Map (PGA, 2% in 50 years)
- Maps: Conterminous US
- GIS Shapefiles (PGA, 2% in 50yrs) (5MB Zip)
- Source code
- Faults Database Search
- Fault Source Map
- Hazard Model Documentation (USGS OFR 2014-1091)
- OFR 2014-1091 Errata and User Q & A
- Geodetic and Geologic Slip Model Documentation (USGS OFR 2014-1293)
- Seismic-Hazard Maps for the Conterminous United States, 2014 (USGS Scientific Investigations Map 3325)
The California portion of the 2104 NSHMP is based on the Uniform California Earthquake Rupture Forecast version 3 (UCERF3). The model was developed by Working Group on California Earthquake Probabilities (WGCEP). For more information see:
- Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)-The Time-Independent Model (USGS OFR 2013-1165)
- Working Group on California Earthquake Probabilities (WGCEP)
2008 Long-term Model
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 shaking obtained from interaction in science and engineering workshops involving hundreds of participants, review by several science organizations and State surveys, and advice from two expert panels.
The new probabilistic hazard maps represent an update of the 2002 seismic hazard maps developed by Frankel and others (2002), which used the methodology developed for the 1996 version of the maps (Frankel and others, 1996). Algermissen and Perkins (1976) published the first probabilistic seismic hazard map of the United States which was updated in Algermissen and others (1990). The national seismic maps represent our assessment of the “best available science” in earthquake hazards estimation for the United States.
- Maps - Revision III
- Ratio Maps - Revision III
- Gridded Ground Motion Data - Revision III
- Hazard Curve Data - Revision III
- Source Code - Revision III
- Faults Database Search
- Fault Source Map
- Documentation for the 2008 Update of the United States National Seismic Hazard Maps (USGS OFR 2008-1128)
- Revision I, May 2008
- Revision II, December 2008 (the basis for the Design Maps)
- Revision III, January 2010
- 2008 United States National Seismic Hazard Maps - (USGS Fact Sheet 2008-3018)
- Seismic-Hazard Maps for the Conterminous United States, 2008 (USGS Scientific Investigations Map 3195)
- Appendix L: Cascadia Subduction Zone (USGS OFR 2007-1437L)
- Earthquake Hazard in the New Madrid Seismic Zone Remains a Concern (USGS Fact Sheet 2009-3071)
- The Uniform California Earthquake Rupture Forecast, Version 2 (UCERF2) (USGS OFR 2007-1437)
- Working Group on California Earthquake Probabilities
- Ground Motion Attenuation Relations for the Central and Eastern United States (USGS-funded)
2002 Long-term Model
Following the release of the 2002 United States hazard maps and data, two subsequent updates were released. The first in April of 2003 and the second in October of 2003. Descriptions of each release can be found below. What is currently made available on our web site reflects the updated data and image files.
- Source Code is not available.
- Faults Database Search
- Fault Source Map
- Documentation for the 2002 Update of the National Seismic Hazard Maps (USGS OFR 02-420)
- Revision I, April 2003
- Revision II, October 2003
- Implosion, Earthquake, and Explosion Recordings from the 2000 Seattle Kingdome Seismic Hazards Investigation of Puget Sound (SHIPS), Washington (USGS OFR 02-123)
- Investigation of an Earthquake Swarm near Trinidad, Colorado, August-October 2001 (USGS OFR 02-0073)
1996 Long-term Model
The computations for these maps and data used 50 year return periods on firm rock at 760 m/sec. All of the maps were prepared by combining hazard derived from spatially- smoothed historic seismicity with hazard from fault-specific sources. For more information please read our full documentation.
Although these maps have been used by the U.S. Geological Survey, no warranty, expressed or implied is made by the USGS as to the accuracy of the maps and related material nor shall the fact of distribution constitute any such warranty, and no responsibility is assumed by the USGS in connection therewith.
- Source Code is not available.
- National Seismic Hazard Maps: Documentation June 1996 (OFR 96-532) and Figures from Open-File Report (6 MB Zip file)
- Hazard Maps Help Save Lives and Property (USGS Fact Sheet 96-183)
- Site-Response Maps for the Los Angeles Region Based on Earthquake Ground Motions (USGS OFR 96-723)
- Preparation of Earthquake Catalogs for the National Seismic-Hazard Maps : Contiguous 48 States (USGS OFR 97-464)
- Seismic-Hazard Maps for the Conterminous United States (USGS OFR 97-131)
- Seismic-Hazard Maps for California, Nevada, and Western Arizona/Utah (USGS OFR 97-130_)