2008 National Seismic Hazard Maps - Source Parameters

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Fault Name	State
Cape Blanco anticline	Oregon

GEOMETRY
Dip (degrees)	45
Dip direction	S
Sense of slip	thrust
Rupture top (km)	0
Rupture bottom (km)	15
Rake (degrees)	90
Length (km)	47

MODEL VALUES
Probability of activity	0.5
Minimum magnitude	6.5
Maximum magnitude	7.02
b-value	0.8

Assigned Dip	Fault-Parallel Slip Rate	Width	Annual Rate	a-value
45	1.98	21.2	1.56e-03	2.202

Comments
Kelsey (1990) measured uplifts of marine terraces that are arched over the anticline. The preferred ages for the terraces are 80 ka and 105 ka. Kelsey (1990) calculated a maximum uplift rate of 1.4 mm/yr for the 105-ka terrace. Geomatrix Consultants, Inc. (1995) attributed the arching and growth of the anticline to an underlying blind thrust fault.

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. Kelsey, H.M., 1990, Late Quaternary deformation of marine terraces on the Cascadia subduction zone near Cape Blanco, Oregon: Tectonics, v. 9, no. 5, p. 983-1014.