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Wet SHIPS

(From the Overview) Seismic hazards in the Puget Sound are dependent on the locations of active faults (those with earthquakes occurring on them in the recent past) and knowing how, how much, and how often slip occurs on those faults. Slip can occur without earthquakes (aseismically) but more often it occurs after enough tension builds up to suddently override the friction on the fault surface. The sudden motion on the faults is an earthquake.

Research on the ground (paleoseismology) has revealed repeated occurrences of earthquakes in the Puget Sound region. The search for the faults on which those earthquakes occurred is more difficult because of the large surface area covered by water, and also by vegetation and urban development.

     
University of Washington Research Vessel Thomas G. Thompson (285 feet long) (left) and
Canadian Research Vessel John P. Tully (240 feet long) (rght)

The USGS spearheaded a search using oil exploration technology to 'see' into the earth and locate faults in the Puget Sound. They also need to determine the seismic velocities in the subsurface in order to predict ground shaking amplification in the region. A group of scientists from universities and government agencies (consortium) are working together to understand where these faults are, which ones can still produce earthquakes, and how often earthquakes occur.

Wet SHIPS focused on seismic reflection work in the Sound and Strait: Operations

A data report is online: Wide-Angle Seismic Recordings from the 1998 Seismic Hazards Investigation of Puget Sound (SHIPS), Western Washington and British Columbia

source and receiver locations