2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

New Search

Fault Name	State
Steens fault zone	Oregon

GEOMETRY
Dip (degrees)	50/40/60
Dip direction	E
Sense of slip	normal
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	-90
Length (km)	214

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	Annual Rate	a-value	Branch Weight
40	0.47	23.3		1.946	0.2
50	0.39	19.6	1.24e-04	1.794	0.6
60	0.35	17.3		2.285	0.2

Comments
Assigned slip rate based on long-term (Miocene) slip rate of Hemphill-Haley (1987) and Hemphill-Haley and others (1989; 1999). 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
Hemphill-Haley, M.A., Page, W.D., Burke, R., and Carver, G.A., 1989, Holocene activity of the Alvord Fault, Steens Mountain, southeastern Oregon: Technical report to Woodward-Clyde Consultants, under Contract Grant No. 14-08-0001-G1333, March 1989, 45 p. Hemphill-Haley, M.A., 1987, Quaternary stratigraphy and late Holocene faulting along the base of the eastern escarpment of Steens Mountain, southeastern Oregon: Humboldt State University, unpublished M.S. thesis, 84 p., 1 pl., scale 1:24,000. Hemphill-Haley, M.A., Carver, G.A., and Burke, B., 1999, Late Quaternary stratigraphy and Holocene faulting along the eastern margin of Steens Mountain, southeastern Oregon, in Quaternary geology of the northern Quinn River and Alvord Valleys, southeastern Oregon: Friends of the Pleistocene field trip guide, September 24-26, 1999, Appendix 5, p. 1-26. 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

Hemphill-Haley, M.A., Page, W.D., Burke, R., and Carver, G.A., 1989, Holocene activity of the Alvord Fault, Steens Mountain, southeastern Oregon: Technical report to Woodward-Clyde Consultants, under Contract Grant No. 14-08-0001-G1333, March 1989, 45 p.
Hemphill-Haley, M.A., 1987, Quaternary stratigraphy and late Holocene faulting along the base of the eastern escarpment of Steens Mountain, southeastern Oregon: Humboldt State University, unpublished M.S. thesis, 84 p., 1 pl., scale 1:24,000.
Hemphill-Haley, M.A., Carver, G.A., and Burke, B., 1999, Late Quaternary stratigraphy and Holocene faulting along the eastern margin of Steens Mountain, southeastern Oregon, in Quaternary geology of the northern Quinn River and Alvord Valleys, southeastern Oregon: Friends of the Pleistocene field trip guide, September 24-26, 1999, Appendix 5, p. 1-26.
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.