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Imaging the Seattle Fault Zone with high-resolution seismic tomography

January 1, 2001

The Seattle fault, which trends east-west through the greater Seattle metropolitan area, is a thrust fault that, around 1100 years ago, produced a major earthquake believed to have had a magnitude greater than 7. We present the first high resolution image of the shallow P wave velocity variation across the fault zone obtained by tomographic inversion of first arrivals recorded on a seismic reflection profile shot through Puget Sound adjacent to Seattle. The velocity image shows that above 500 m depth the fault zone extending beneath Seattle comprises three distinct fault splays, the northernmost of which dips to the south at around 60??. The degree of uplift of Tertiary rocks within the fault zone suggests that the slip-rate along the northernmost splay during the Quaternary is 0.5 mm a-1, which is twice the average slip-rate of the Seattle fault over the last 40 Ma.

Publication Year 2001
Title Imaging the Seattle Fault Zone with high-resolution seismic tomography
DOI 10.1029/2000GL012778
Authors A.J. Calvert, M. A. Fisher
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Index ID 70023482
Record Source USGS Publications Warehouse