2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

New Search

Fault Name	State
Sevier/Toroweap fault zone (southern)	Arizona

GEOMETRY
Dip (degrees)	60/50/40
Dip direction	W
Sense of slip	normal
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	-90
Length (km)	171

MODEL VALUES
Probability of activity	1
Minimum magnitude	6.5
Maximum magnitude	7.50
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	a-value	Branch Weight
40	0.17	23.3	1.412	0.2
50	0.14	19.6	1.260	0.6
60	0.13	17.3	1.153	0.2

Comments
The preferred vertical slip rate is the average vertical displacement rate from study by Fenton and others (2001). The characteristic magnitude for this fault is fixed at M7.5 even though the length of the fault would permit a larger earthquake. Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Selected References
Fenton, C.R., Webb, R.H., Pearthree, P.A., Cerling, T.E., and Poreda, R.J., 2001, Displacement rates on the Toroweap and Hurricane faults—Implications for Quaternary downcutting in the Grand Canyon, Arizona: Geology, v. 29, p. 1035-1038. 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

Fenton, C.R., Webb, R.H., Pearthree, P.A., Cerling, T.E., and Poreda, R.J., 2001, Displacement rates on the Toroweap and Hurricane faults—Implications for Quaternary downcutting in the Grand Canyon, Arizona: Geology, v. 29, p. 1035-1038.
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.