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Open-File Report 96-532

National Seismic Hazard Maps: Documentation June 1996

By Arthur Frankel, Charles Mueller, Theodore Barnhard, David Perkins, E.V. Leyendecker, Nancy Dickman, Stanley Hanson, and Margaret Hopper

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Faults

For the June maps we explicitly calculated the hazard from about 500 Quaternary faults or fault segments. We considered faults where geologic slip rates have been determined or estimates of recurrence times have been made from trenching studies. We have compiled a table of the parameters used in the hazard calculations, along with references (see our Internet Website). Figures 24 and 25 are maps of the faults used in the June maps.

Below we cite individuals who worked on compilations of fault data for the maps or who provided their data for the maps. Complete references for the fault parameters are contained in the fault table on our Website.

Jim Lienkaemper developed a comprehensive table of consensus slip rate and magnitude information for northern California faults (Lienkaemper, written comm. 1995, 1996). He enlisted a set of USGS and non-USGS geologists to evaluate and compile slip rates and other fault information. Dave Schwartz was also essential to this process. These slip rates were used in the determination of recurrence times.

Pat McCrory spearheaded another effort to compile slip rate information for faults in the Humboldt Bay region of northern California. She convened a panel of experts to collect these critical data (McCrory, 1996) .

Mark Petersen, Chris Cramer, and Bill Bryant (CDMG) developed a slip rate table for southern California which is an extension of Petersen and Wesnousky (1994). This table was modified after extensive consultation with geologists working on southern California tectonics. The slip rates and segmentation for the San Jacinto and Elsinore faults were taken from consensus values derived under the auspices of the Southern California Earthquake Center (Working Group on California Earthquake Probabilities [WGCEP], 1995). Slip rates and recurrence times of some other southern California faults were from WGCEP (1995).

Petersen, Cramer, and Bryant assembled a database containing recurrence times, a-values and maximum magnitudes for California faults, with the recurrence times usually based on the consensus slip rates described above. For California, the maximum magnitudes were determined from the fault area. We used the CDMG database directly in our hazard maps.

Craig dePolo provided us with slip rates he has derived for Nevada faults (from dePolo, 1996) using geomorphologic criteria. We have included Nevada faults with slip rates of >= 0.1mm/yr in the maps. We judged that these were the more reliable slip rates. We found that including Nevada faults with lower slip rate estimates made little difference to the hazard maps.

For Oregon, we used fault information from Pezzopane (1993) and the compilation of Geomatrix (1995), who produced seismic hazard maps for that state. We based our recurrence calculations on the slip rates given in Geomatrix (1995).

 

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