2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

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Fault Name	State
Juniper Mountain fault	Oregon

GEOMETRY
Dip (degrees)	50/40/60
Dip direction	N
Sense of slip	normal
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	-90
Length (km)	18

MODEL VALUES
Probability of activity	1
Minimum magnitude	6.5
Maximum magnitude	6.53
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	Annual Rate	a-value	Branch Weight
40	0.02	23.3	2.76e-05	0.675	0.2
50	0.01	19.6	1.94e-05	0.523	0.6
60	0.01	17.3	1.52e-05	0.416	0.2

Comments
The fault has Quaternary scarps but no data from which to calculate a slip rate. However, Geomatrix Consultants, Inc. (1995) proposed a three-point distribution of possible slip rates, and used geomorphic expression of the fault and possibly some preliminary estimates of scarp heights to suggest a probability for each rate: 0.01 mm/yr (probability 0.5), 0.05 mm/yr (0.4), and 0.1 mm/yr (0.1). The highest-probability slip rate (0.01 mm/yr) is used here. Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Comments

The fault has Quaternary scarps but no data from which to calculate a slip rate. However, Geomatrix Consultants, Inc. (1995) proposed a three-point distribution of possible slip rates, and used geomorphic expression of the fault and possibly some preliminary estimates of scarp heights to suggest a probability for each rate: 0.01 mm/yr (probability 0.5), 0.05 mm/yr (0.4), and 0.1 mm/yr (0.1). The highest-probability slip rate (0.01 mm/yr) is used here. Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Selected References
Geomatrix Consultants, Inc., 1995, Seismic design mapping, State of Oregon: Technical report to Oregon Department of Transportation, Salem, Oregon, under Contract 11688, January 1995, unpaginated, 5 pls., scale 1:1,250,000. 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

Geomatrix Consultants, Inc., 1995, Seismic design mapping, State of Oregon: Technical report to Oregon Department of Transportation, Salem, Oregon, under Contract 11688, January 1995, unpaginated, 5 pls., scale 1:1,250,000.
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.