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Urban Seismic Hazards Active

By Earthquake Hazards Program October 10, 2019

  

California

  • Liquefaction Hazard Maps for San Francisco Bay Area

    The liquefaction hazard maps for the SF Bay Area, NW Alameda County, and N Santa Clara Valley predict 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).

  • Hazard Maps for San Francisco Bay Area

    Association of Bay Area Governments offers shaking maps, liquefaction maps, predictive transportation disruption maps, and more.

  • Seismic Hazard Maps for California

    In 1880 the California Legistlature established the State Mining Bureau which has evolved during its 127 years of continuous service into the modern California Geological Survey (CGS).

Central and Eastern US

  • Central U.S. Seismic Velocity Model

    The model covers a region of approximately 650,000 km2 and includes several urban areas, such as Little Rock, AR; Evansville, IN; Memphis, TN; Nashville, TN; Louisville, KY; and St. Louis, MO.

  • Central and Eastern U.S. Hazard and Seismicity Map

    This map shows earthquakes (circles) greater than magnitude 3.0 since 1974 plotted on the 2014 USGS National Seismic Hazard Map for the central and eastern United States. Warmer colors on this map indicate areas of higher hazard. Larger earthquakes are represented by larger circles. (PDF)

  • Memphis, Shelby County Earthquake Hazards Mapping

    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.

  • Evansville Area Earthquake Hazards Mapping

    In tri-state Evansville area of Indiana, Kentucky, and Illinois the USGS is partnering with a local working group to produce urban earthquake hazard maps for the community.

  • St. Louis Area Earthquake Hazards Mapping

    In the St. Louis area of Missouri and Illinois the USGS is partnering with a local working group to produce urban earthquake hazard maps for the community.

Pacific Northwest

Below are publications associated with this project.

Sedimentary basin effects in Seattle, Washington: Ground-motion observations and 3D simulations

Seismograms of local earthquakes recorded in Seattle exhibit surface waves in the Seattle basin and basin-edge focusing of S waves. Spectral ratios of Swaves and later arrivals at 1 Hz for stiff-soil sites in the Seattle basin show a dependence on the direction to the earthquake, with earthquakes to the south and southwest producing higher average amplification. Earthquakes to the southwest typica
Authors
Arthur Frankel, William Stephenson, David Carver

Velocity and Density Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion Simulations

In support of earthquake hazards and ground motion studies in the Pacific Northwest, three-dimensional P- and S-wave velocity (3D Vp and Vs) and density (3D rho) models incorporating the Cascadia subduction zone have been developed for the region encompassed from about 40.2°N to 50°N latitude, and from about -122°W to -129°W longitude. The model volume includes elevations from 0 km to 60 km (eleva
Authors
William J. Stephenson
By
Natural Hazards Mission Area, Earthquake Hazards Program

Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity

This report presents probabilistic seismic hazard maps for Seattle, Washington, based on over 500 3D simulations of ground motions from scenario earthquakes. These maps include 3D sedimentary basin effects and rupture directivity. Nonlinear site response for soft-soil sites of fill and alluvium was also applied in the maps. The report describes the methodology for incorporating source and site dep
Authors
Arthur D. Frankel, William J. Stephenson, David L. Carver, Robert A. Williams, Jack K. Odum, Susan Rhea
By
Natural Hazards Mission Area, Earthquake Hazards Program, Geologic Hazards Science Center

Three-dimensional simulations of ground motions in the Seattle region for earthquakes in the Seattle fault zone

We used the 3D finite-difference method to model observed seismograms of two earthquakes (ML 4.9 and 3.5) in the Seattle region and to simulate ground motions for hypothetical M 6.5 and M 5.0 earthquakes on the Seattle fault, for periods greater than 2 sec. A 3D velocity model of the Seattle Basin was constructed from studies that analyzed seismic-reflection surveys, borehole logs, and gravity and
Authors
A. Frankel, W. Stephenson