Paleoseismicity and Seismotectonics in the Puget Sound Region from Geologic and Geophysical Studies of Puget Sound and Nearby Lakes

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9418465 Karlin This research is to conduct geological, geophysical, and geotechnical studies of Puget Sound, Lake Washington, and other lakes in the Puget Lowland to map the submarine expression of large faults, map the distribution of subaqueous landslides,and obtain sedimentary records of earthquake history during the Holocene. In Puget Sound, seismic reflection profiling, side-scan swath surveying, and coring operations will be conducted to examine the Seattle Fault system for evidence of recent movement and trace its submarine expression through Lake Sammamish, Lake Washington, Puget Sound to Hood Canal. Zones of subaqueous slumping will be mapped, dated and analyzed to determine if they are of seismogenic origin. On selected submarine landslides in Lake Washington, existing geotechnical information will be combined with geophysical mapping and core analysis to model minimum accelerations (hence, earthquake intensities) needed to trigger slope failure. The sedimentary earthquake record obtained from Lake Washington will be verified and extended by examining anomalous disturbances in sedimentary sequences in other lakes in the region. This work should help in estimates of seismic risk in the Seattle-Bellevue-Kirkland-Everett-Tacoma area. This research is a component of the National Earthquake Hazard Reduction Program. *** ??