2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

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Fault Name	State
Grand Valley fault	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)	55

MODEL VALUES
Probability of activity	1
Minimum magnitude	6.5
Maximum magnitude	7.10
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	Annual Rate	a-value	Branch Weight
40	1.71	23.3	1.32e-03	2.217	0.2
50	1.44	19.6	9.31e-04	2.065	0.6
60	1.27	17.3	7.29e-04	1.958	0.2

Comments
The preferred vertical slip rate is the highest rate that can be calculated from reported 8.3-11.6 m scarps on 11-15 ka deposits (Piety and others, 1986; 1992; Anders and others, 1990). Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Selected References
Anders, M.H., Rodgers, D.W., McCalpin, J.P., and Haller, K.M., 1990, Late Tertiary and Quaternary faulting north and south of the eastern Snake River Plain, in Roberts, S., ed., Geologic field tours of western Wyoming: Geological Survey of Wyoming Public Information Circular 29, p. 1-38. Piety, L.A., Sullivan, J.T., and Anders, M.H., 1992, Segmentation and paleoseismicity of the Grand Valley fault, southeastern Idaho and western Wyoming, in Link, P.K., Kuntz, M.A., and Platt, L.B., eds., Regional geology of eastern Idaho and western Wyoming: Geological Society of America Memoir 179, p. 155-182. Piety, L.A., Wood, C.K., Gilbert, J.D., Sullivan, J.T., and Anders, M.H., 1986, Seismotectonic study for Palisades Dam and Reservoir, Palisades Project: Bureau of Reclamation Seismotectonic Report 86-3, 198 p., 2 pls. 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. Warren, G.A., 1992, Quaternary geology and neotectonics of southern Star Valley and the southwest flank of the Salt River Range, western Wyoming: Logan, Utah State University, unpublished M.S. thesis, 96 p., 3 pls., scale 1:24,000.

Selected References

Anders, M.H., Rodgers, D.W., McCalpin, J.P., and Haller, K.M., 1990, Late Tertiary and Quaternary faulting north and south of the eastern Snake River Plain, in Roberts, S., ed., Geologic field tours of western Wyoming: Geological Survey of Wyoming Public Information Circular 29, p. 1-38.
Piety, L.A., Sullivan, J.T., and Anders, M.H., 1992, Segmentation and paleoseismicity of the Grand Valley fault, southeastern Idaho and western Wyoming, in Link, P.K., Kuntz, M.A., and Platt, L.B., eds., Regional geology of eastern Idaho and western Wyoming: Geological Society of America Memoir 179, p. 155-182.
Piety, L.A., Wood, C.K., Gilbert, J.D., Sullivan, J.T., and Anders, M.H., 1986, Seismotectonic study for Palisades Dam and Reservoir, Palisades Project: Bureau of Reclamation Seismotectonic Report 86-3, 198 p., 2 pls.
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.
Warren, G.A., 1992, Quaternary geology and neotectonics of southern Star Valley and the southwest flank of the Salt River Range, western Wyoming: Logan, Utah State University, unpublished M.S. thesis, 96 p., 3 pls., scale 1:24,000.