2008 National Seismic Hazard Maps-Fault parameters
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Fault Name State
Mill Creek Thrust fault Washington
GEOMETRY
Dip (degrees) 60
Dip direction S
Sense of slip reverse
Rupture top (km) 0
Rupture bottom (km) 15
Rake (degrees) 90
Length (km) 56
MODEL VALUES
Probability of activity 1
Minimum magnitude 6.5
Maximum magnitude 7.11
b-value 0.8
Assigned Dip Fault-Parallel Slip Rate Width Annual Rate a-value
60 0.04 17.3 2.48e-05 0.501
Comments
Geomatrix Consultants, Inc. (1996) cited 500 m of vertical offset of a 10.5-16.0 Ma basalt, and calculated a fault-parallel slip rate. We used their data and calculated a vertical slip rate of 0.038 mm/yr, from the average of the rates indicated by the range in age of the basalt.