2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

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Fault Name	State
Bear River fault zone	Wyoming

GEOMETRY
Dip (degrees)	50/40/60
Dip direction	W
Sense of slip	normal
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	-90
Length (km)	37

MODEL VALUES
Probability of activity	1
Minimum magnitude	6.5
Maximum magnitude	6.90
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	Annual Rate	a-value	Branch Weight
40	2.33	23.3	4.35e-04	2.283	0.2
50	1.96	19.6	4.35e-04	1.689	0.6
60	1.73	17.3	4.35e-04	2.283	0.2

Comments
Characteristic rate fixed to represent recurrence of 3 k.y. based on studies by West (1994). Assigned vertical slip rate of 1.5 mm/yr is consensus value reported by Lund (2005) based on original investigation by West (1994). Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Selected References
West, M.W., 1994, Paleoseismology of Utah, volume 4—Seismotectonics of north-central Utah and southwestern Wyoming: Utah Geological Survey Special Study 82, 93 p., 5 pls., http://ugspub.nr.utah.gov/publications/special_studies/SS-82.pdf Lund, W.R., 2005, Consensus preferred recurrence interval and vertical slip rate estimates—Review of Utah paleoseismic-trenching data by the Utah Quaternary Fault Parameters Working Group: Utah Geological Survey Bulletin 134, compact disk. 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, ugspub.nr.utah.gov/publications/open_file_reports/OFR-477.pdf.

Selected References

West, M.W., 1994, Paleoseismology of Utah, volume 4—Seismotectonics of north-central Utah and southwestern Wyoming: Utah Geological Survey Special Study 82, 93 p., 5 pls., http://ugspub.nr.utah.gov/publications/special_studies/SS-82.pdf
Lund, W.R., 2005, Consensus preferred recurrence interval and vertical slip rate estimates—Review of Utah paleoseismic-trenching data by the Utah Quaternary Fault Parameters Working Group: Utah Geological Survey Bulletin 134, compact disk.
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, ugspub.nr.utah.gov/publications/open_file_reports/OFR-477.pdf.