HR: 17:45h
AN: S54A-07 INVITED     [Abstracts]
TI: Recent high-resolution seismic reflection studies of active faults in the Puget Lowland
AU: * Liberty, L M
EM: lml@cgiss.boisestate.edu
AF: Department of Geosciences Boise State University, 1910 University Dr, Boise, ID 83725-1536 United States
AU: Pratt, T L
EM: tpratt@ocean.washington.edu
AF: U. S. Geological Survey, University of Washington School of Oceanography Box 357940, Seattle, Wa 98195 United States
AB: In the past four years, new high-resolution seismic surveys have filled in key gaps in our understanding of active structures beneath the Puget Lowland, western Washington State. Although extensive regional and high-resolution marine seismic surveys have been fundamental to understanding the tectonic framework of the area, these marine profiles lack coverage on land and in shallow or restricted waterways. The recent high-resolution seismic surveys have targeted key structures beneath water bodies that large ships cannot navigate, and beneath city streets underlain by late Pleistocene glacial deposits that are missing from the waterways. The surveys can therefore bridge the gap between paleoseismic and marine geophysical studies, and test key elements of models proposed by regional-scale geophysical studies. Results from these surveys have: 1) documented several meters of vertical displacement on at least two separate faults in the Olympia area; 2) clarified the relationship between the Catfish Lake scarp and the underlying kink band in the Tacoma fault zone; 3) provided a first look at the structures beneath the north portion of the western Tacoma fault zone, north of previous marine profiles; 4) documented that deformation along the Seattle fault extends well east of Lake Sammamish; 5) imaged the Seattle fault beneath the Vasa Park trench; and 6) documented multiple fault strands in and south of the Seattle fault zone south of Bellevue. The results better constrain interpretations of paleoseismic investigations of past earthquakes on these faults, and provide targets for future paleoseismic studies.
DE: 7221 Paleoseismology (8036)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8108 Continental tectonics: compressional
DE: 8123 Dynamics: seismotectonics
SC: Seismology [S]
MN: Fall Meeting 2005