2008 National Seismic Hazard Maps - Fault Parameters

2007 National Seismic Hazard Maps-Fault parameters
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Fault Name State
Beaverhead fault Idaho
MODEL VALUES
Slip rate (vertical or horizontal in mm/yr) 0.12
Probability of activity 1
Minimum magnitude 6.5
Maximum magnitude 7
FAULT GEOMETRY
Dip (degrees) 50/60/40
Dip direction SW
Sense of slip normal
Rupture top (km) 0
Rupture bottom (km) 15
Rake (degrees) -90
Length (km) 134
Assigned Dip Fault Parallel Slip Rate Width Characteristic Magnitude Characteristic Rate Weight
40 0.19 23.3 7 0.2
50 0.16 19.6 7 0.6
60 0.14 17.3 7 0.2
Comments
The preferred vertical slip rate is based on geomorphic studies of multiple-earthquake scarps on early Pinedale-equivalent (25-30 ka) surfaces on two of the central segments of the fault (Haller, 1988) that suggest an average of 0.12 mm/yr. Assigned characteristic magnitude based on Borah Peak earthquake. Dip of fault changed to 50° based on redefined regional default value (Lund, 2006).
Selected References
Haller, K.M., 1988, Segmentation of the Lemhi and Beaverhead faults, east-central Idaho, and Red Rock fault, southwest Montana, during the late Quaternary: Boulder, University of Colorado, unpublished M.S. thesis, 141 p., 10 pls.
Scott, W.E., Pierce, K.L., and Hait, M.H., Jr., 1985, Quaternary tectonic setting of the 1983 Borah Peak earthquake, central Idaho: Bulletin of the Seismological Society of America, v. 75, p. 1053-1066.
Lund, W.R., ed., 2006, Basin and Range Province Earthquake Working Group seismic-hazard recommendations to the U.S. Geological Survey National Seismic Hazard Mapping Program: Utah Geological Survey Open-File Report 477, 23 p.