2008 National Seismic Hazard Maps

2008 National Seismic Hazard Maps-Fault parameters

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Fault Name	State
Emigrant fault	Montana

GEOMETRY
Dip (degrees)	50/60/40
Dip direction	NW
Sense of slip	normal
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	-90
Length (km)	57

MODEL VALUES
Probability of activity	1
Minimum magnitude	6.5
Maximum magnitude	7.12
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	Annual Rate	a-value	Branch Weight
40	0.39	23.3	2.88e-04	1.577	0.2
50	0.33	19.6	2.03e-04	1.424	0.6
60	0.29	17.3	1.59e-04	1.318	0.2

Comments
The only known published slip rate is from Pierce and Morgan (1992) based on field data of Personius (1982) and thus represents our preferred vertical slip rate. Dip of fault changed to 50? based on redefined regional default value (Lund, 2006).

Selected References
Personius, S.F., 1982, Geologic setting and geomorphic analysis of Quaternary fault scarps along the Deep Creek fault, upper Yellowstone valley, south-central Montana: Bozeman, Montana State University, unpublished M.S. thesis, 77 p., 1 sheet, scale 1:125,000. Pierce, K.L., and Morgan, L.A., 1992, The track of the Yellowstone hot spot—Volcanism, faulting, and uplift, 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. 1-53, 1 pl. 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

Personius, S.F., 1982, Geologic setting and geomorphic analysis of Quaternary fault scarps along the Deep Creek fault, upper Yellowstone valley, south-central Montana: Bozeman, Montana State University, unpublished M.S. thesis, 77 p., 1 sheet, scale 1:125,000.
Pierce, K.L., and Morgan, L.A., 1992, The track of the Yellowstone hot spot—Volcanism, faulting, and uplift, 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. 1-53, 1 pl.
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.