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3D Crustal Structure and Long-Period Ground Motions from a M9.0 Megathrust Earthquake in the Pacific Northwest Region

Kim B. Olsen, & William J. Stephenson

Published April 2008, SCEC Contribution #1142

We have developed a community velocity model for the Pacific Northwest region from northern California to southern Canada and carried out the first 3D simulation of a Mw 9.0 megathrust earthquake rupturing along the Cascadia subduction zone using a parallel supercomputer. A long-period (<0.5 Hz) source model was designed by mapping the inversion results for the December 26, 2004 Sumatra–Andaman earthquake (Han et al., Science 313(5787):658–662, 2006) onto the Cascadia subduction zone. Representative peak ground velocities for the metropolitan centers of the region include 42 cm/s in the Seattle area and 8–20 cm/s in the Tacoma, Olympia, Vancouver, and Portland areas. Combined with an extended duration of the shaking up to 5 min, these long-period ground motions may inflict significant damage on the built environment, in particular on the highrises in downtown Seattle.

Citation
Olsen, K. B., & Stephenson, W. J. (2008). 3D Crustal Structure and Long-Period Ground Motions from a M9.0 Megathrust Earthquake in the Pacific Northwest Region. Journal of Seismology, 12(2), 145-159. doi: 10.1007/s10950-007-9082-y.