Open-File Report 2008–1128
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 National Seismic Hazard Maps represent our assessment of the "best available science" in earthquake hazards estimation for the United States (maps of Alaska and Hawaii as well as further information on hazard across the United States are available on our Web site at http://earthquake.usgs.gov/research/hazmaps/). |
Posted May 2008 |
Petersen, Mark D., Frankel, Arthur D., Harmsen, Stephen C., Mueller, Charles S., Haller, Kathleen M., Wheeler, Russell L., Wesson, Robert L., Zeng, Yuehua, Boyd, Oliver S., Perkins, David M., Luco, Nicolas, Field, Edward H., Wills, Chris J., and Rukstales, Kenneth S., 2008, Documentation for the 2008 Update of the United States National Seismic Hazard Maps: U.S. Geological Survey Open-File Report 2008–1128, 61 p.
Introduction
General Methodology
Seismicity-Derived Hazard Component
Fault Sources
Attenuation Relations
Central and Eastern United States
Source Model: Seismicity-Derived Hazard Component
Catalog
Maximum Magnitude
Smoothed-Gridded Seismicity
Uniform Background Zones
Special Zones
Source Model—Faults
New Madrid Seismic Zone
Rupture Sources
Magnitudes
Earthquake Recurrence
Charleston, South Carolina, Seismic Zone
Meers Fault, Oklahoma, and Cheraw Fault, Colorado
Ground-Motion Relations
Western United States
Source Model—Seismicity Derived Hazard Component
Catalog
Maximum Magnitude
Smoothed-Gridded Seismicity
Uniform Background Zones
Special Zones
Source Model—Geodetically Derived Areal Source Zones (C Zones)
Source Model—Faults
Magnitudes
Earthquake Recurrence
Intermountain West Fault Sources
Pacific Northwest—Cascadia Fault Sources
California Fault Sources
Ground-Motion Relations
Crustal Faults
Subduction Zone/Plate Interface
Subduction Zone—In-Slab
Results of the Seismic Hazard Calculations
Central and Eastern United States Maps
Western United States Maps
Conclusions and Proposed Future Improvements to Maps
Acknowledgements
References
Appendixes A–K
A. Depth to the Top of Rupture (Ztor) for Western United States Faults
B. Fault Distances to Nonplanar Fault
C. Distance to a Fault with Random Strike
D. Modeling Dip-Slip Background Sources
E. The Gutenberg-Richter Part of the Magnitude-Frequency Distribution for Western United States Faults
F. New Madrid Temporal Cluster Model
G. Parameters for Faults in the Intermountain West
H. Parameters for Faults in the Pacific Northwest
I. Parameters for Faults in California
J. Fault-Model Changes in the Western United States
K. Cascadia Subduction Zone