2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

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Fault Name	State
Big Chino fault	Arizona

GEOMETRY
Dip (degrees)	60/50/40
Dip direction	SW
Sense of slip	normal
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	-90
Length (km)	49

MODEL VALUES
Probability of activity	1
Minimum magnitude	6.5
Maximum magnitude	7.04
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	Annual Rate	a-value	Branch Weight
40	0.13	23.3	1.08e-04	1.062	0.2
50	0.11	19.6	7.59e-05	0.910	0.6
60	0.10	17.3	5.94e-05	0.803	0.2

Comments
The preferred vertical slip rate is based on upper Pleistocene alluvial deposits (estimated 80-100 ka) that trenching showed to be offset vertically 7-8 m (Euge and others, 1992). Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Selected References
Pearthree, P.A., Menges, C.M., and Mayer, L., 1983, Distribution, recurrence, and possible tectonic implications of late Quaternary faulting in Arizona: Arizona Geological Survey Open-File Report 83-20, 51 p. Euge, K.M., Schell, B.A., and Lam, I.P., 1992, Development of seismic acceleration maps for Arizona: Arizona Department of Transportation Report AZ92-344, 327 p., 5 sheets, scale 1:1,000,000. 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

Pearthree, P.A., Menges, C.M., and Mayer, L., 1983, Distribution, recurrence, and possible tectonic implications of late Quaternary faulting in Arizona: Arizona Geological Survey Open-File Report 83-20, 51 p.
Euge, K.M., Schell, B.A., and Lam, I.P., 1992, Development of seismic acceleration maps for Arizona: Arizona Department of Transportation Report AZ92-344, 327 p., 5 sheets, scale 1:1,000,000.
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.