Recent studies indicate that there have been several episodes of coseismic subsidence along the coasts of central and southern Oregon and northern California during the past several thousand years. A three-dimensional dislocation model is used to predict the amount of coseismic subsidence produced by different magnitude earthquakes. The magnitude of coseismic subsidence is equal to the interseismic uplift in an elastic earth model. The model is constrained mainly by interseismic uplift data from repeated leveling surveys in western Oregon over the past 50–60 yr. The results suggest that earthquakes with moment magnitude of ∼8.5 are required to produce the coseismic subsidence observed. The model also suggests that larger earthquakes (Mw > 9.0) would produce coseismic subsidence in areas where none is observed in the geologic record.

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