Hazard Maps and Data

USGS National Seismic Hazard Maps, Data, and Documentation

  • Lower 48 [ 2014 |  2008 |  2002 |  1996 ]

    US Conterminous 48 States

    The 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.

    2014 Hazard Map - PGA, 2% in 50 years (2MB PDF)
    2008 Hazard Map (PGA, 2% in 50 years) Download Formats : [ EPS | PDF | JPG ]

  • Alaska [ 2007 |  1999 ]

    Alaska

    Probabilistic seismic hazard maps have been prepared for Alaska portraying ground motion values (peak ground acceleration and spectral amplitude at periods of 0.2, 0.3 and 1.0 seconds) at probabilities of exceedance of 2% and 10% in 50 years. Preparation of these maps followed the same general strategy as that followed for the U.S.G.S. seismic hazard maps of the contiguous United States, combining hazard derived from spatially-smoothed historic seismicity with hazard from fault-specific sources.

  • Hawaii [ 1998 ]

    Hawaii

    Probabilistic seismic hazard maps were prepared for Hawaii portraying peak horizontal ground acceleration and horizontal spectral response acceleration for 0.2, 0.3, and 1.0 second periods with probabilities of exceedance of 10% in 50 years and 2% in 50 years. This particular data set is for horizontal spectral response acceleration for 1.0 second period with a 10% probability of exceedance in 50 years. All of the maps were prepared by combining hazard derived from spatially- smoothed historic seismicity with hazard from fault-specific sources.

  • Puerto Rico & the U.S. Virgin Islands [ 2003 ]

    PRVI

    We present results of a new probabilistic seismic hazard assessment for Puerto Rico and the U. S. Virgin Islands (PRVI). The study area is located along the boundary between the northeastern Caribbean Sea and the Atlantic Ocean, at the intersection of the Greater and Lesser Antilles Island chains. These islands demarcate the boundary between the North American and Caribbean tectonic plates, with the North American plate moving west-southwestward relative to the Caribbean plate.

  • Guam &Marianas [ 2012 ]

    Guam/Marianas

    USGS Open-File Report 2012-1015: Seismic Hazard Assessment for Guam and the Northern Mariana Islands

  • Samoa & Pacific Islands [ 2012 ]

    Samoa/Pacific Islands

    USGS Open-File Report 2012-1087: Seismic Hazard of American Samoa and Neighboring South Pacific Islands—Data, Methods, Parameters, and Results

USGS Urban & Regional Hazard Maps

  • Seattle Urban Seismic Hazard Maps [ 2007 ]

    Seattle

    The USGS has produced a new series of earthquake hazard maps for the City of Seattle. These ‘urban seismic hazard’ maps provide a much higher-resolution view of the potential for strong earthquake shaking than previously available. This new view is particularly important for Seattle, which sits atop a sedimentary basin that strongly affects the patterns of earthquake ground shaking and therefore, of potential damage.

  • Memphis, Shelby County Seismic Hazard Maps [ 2004 ]

    Memphis

    Memphis, Shelby County, Tennessee, is located where damaging earthquakes are only moderately likely, but the consequences of earthquakes, mainly from the New Madrid seismic zone, can be very high. This densely populated urban area is built on a 1-kilometer-thick sequence of sediments deposited in a trough known as the Mississippi embayment. This thick pile of sediments significantly affects earthquake ground motions. We, the authors, have generated a suite of seismic hazard maps for a six-quadrangle area in Memphis, Shelby County, Tennessee, that accounts for these effects. These maps and their derivative products represent the collaborative efforts of the U.S. Geological Survey (USGS) and its partners.

  • Liquefaction Hazard in Oakland, California [ 2002 ]

    Oakland Liquefaction

    The liquefaction hazard map predicts the approximate percentage of each designated area that will have surface manifestations of liquefaction during an M7.1 earthquake on the Hayward fault. An earthquake of this magnitude is expected if the whole Hayward fault ruptures in a single event (Working Group on California Earthquake Probabilities, 1999). This event dominates the deaggregated hazard near the eastern shore of San Francisco Bay.

Scenarios & Time-Dependent Maps

  • Scenario Shakemaps [ Scenarios ]

    Scenarios

    Earthquake Scenarios describe the expected ground motions and effects of specific hypothetical large earthquakes. In planning and coordinating emergency response, utilities, emergency responders, and other agencies are best served by conducting training exercises based on realistic earthquake situations, ones that they are most likely to face. Scenario earthquakes can fill this role; they can be generated for any potential hypothetical future or past historic earthquake.

  • Time-Dependent Earthquake Probability Maps [ Time-Dependent ]

    Time-Dependent

    Time-dependent models of earthquake occurrence are based on the assumption that the probability of occurrence of an earthquake in a given time period follows a renewal model, that is a lognormal, Brownian Passage Time (BPT), or other probability distribution in which the probability of the event depends on the time since the last event. The time-dependent models are intuitively appealing because they produce results broadly consistent with the elastic rebound theory of earthquakes. The USGS and CGS are beginning to develop these types of hazard products as new geologic and seismic information regarding the dates of previous events along faults becomes available.

Other Foreign Maps and Documentation

  • Southeast Asia [ Tectonophysics Vol 390 pp. 141—158 ] [ Earthquake Summary Poster ] [ Documentation ]

    Sumatra

    The ground motion hazard for Sumatra and the Malaysian peninsula is calculated in a probabilistic framework, using procedures developed for the US National Seismic Hazard Maps. We constructed regional earthquake source models and used standard published and modified attenuation equations to calculate peak ground acceleration at 2% and 10% probability of exceedance in 50 years for rock site conditions. We developed or modified earthquake catalogs and declustered these catalogs to include only independent earthquakes. The resulting catalogs were used to define four source zones that characterize earthquakes in four tectonic environments: subduction zone interface earthquakes, subduction zone deep intraslab earthquakes, strike-slip transform earthquakes, and intraplate earthquakes.

  • State of Gujarat, India [ Tectonophysics Vol. 390 pp.105—115 ]

    India

    We test the sensitivity of seismic hazard to three fault source models for the northwestern portion of Gujarat, India. The models incorporate different characteristic earthquake magnitudes on three faults with individual recurrence intervals of either 800 or 1600 years. These recurrence intervals imply that large earthquakes occur on one of these faults every 266—533 years, similar to the rate of historic large earthquakes in this region during the past two centuries and for earthquakes in intraplate environments like the New Madrid region in the central United States.

  • Afghanistan [ Hazards |  Other USGS Projects ]

    Afghanistan

    Afghanistan is located in the geologically active part of the world where the northward-moving Indian plate is colliding with the southern part of the Eurasian plate at a rate of about 1.7 inches per year. This collision has created the world's highest mountains and causes slips on major faults that generate large, often devastating earthquakes. Every few years a powerful earthquake causes significant damage or fatalities.

  • Global Seismic Hazard Assessment Program [ GSHAP ]

    GSHAP

    The Global Seismic Hazard Assessment Program (GSHAP), a demonstration project of the UN/International Decade of Natural Disaster Reduction, was conducted in the 1992-1998 period with the goal of improving global standards in seismic hazard assessment. The GSHAP Global Seismic Hazard Map has been compiled by joining the regional maps produced for different GSHAP regions and test areas; it depicts the global seismic hazard as peak ground acceleration (pga) with a 10% chance of exceedance in 50 years, corresponding to a return period of 475 years.