2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

New Search

Fault Name	State
Red Rock fault	Montana

GEOMETRY
Dip (degrees)	40/60/50
Dip direction	E
Sense of slip	normal
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	-90
Length (km)	27

MODEL VALUES
Probability of activity	1
Minimum magnitude	6.5
Maximum magnitude	6.73
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	Annual Rate	a-value	Branch Weight
40	0.78	23.3	1.04e-03	2.177	0.2
50	0.65	19.6	7.29e-04	2.024	0.6
60	0.58	17.3	5.70e-04	1.918	0.2

Comments
Preferred vertical slip rate based on about 2.5 m of slip during the most recent event (Stickney and Bartholomew, 1987) and the recurrence interval between the past two events of 5-15 k.y. (Ostenaa and Wood, 1990). Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Selected References
Ostenaa, D., and Wood, C., 1990, Seismotectonic study for Clark Canyon Dam, Pick-Sloan Missouri Basin Program, Montana: U.S. Bureau of Reclamation Seismotectonic Report 90-4, 78 p., 1 pl. 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. Bartholomew, M.J., and Stickney, M.C., 1987, Late Quaternary faulting in southwestern Montana: Geological Society of America Abstracts with Programs, v. 19, p. 258-259.

Selected References

Ostenaa, D., and Wood, C., 1990, Seismotectonic study for Clark Canyon Dam, Pick-Sloan Missouri Basin Program, Montana: U.S. Bureau of Reclamation Seismotectonic Report 90-4, 78 p., 1 pl.
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.
Bartholomew, M.J., and Stickney, M.C., 1987, Late Quaternary faulting in southwestern Montana: Geological Society of America Abstracts with Programs, v. 19, p. 258-259.