The Seattle fault zone is geologically complex and is known to have caused destructive earthquakes. It lies beneath Seattle and Bellevue, but most of it is hidden beneath glacial deposits, forests, water, and urban development.
Richard Blakely and colleagues from the U.S. Geological Survey used the Earth’s magnetic field, measured from a low-flying airplane, to map potentially dangerous areas of the Seattle fault zone. They report their findings in the February issue of the Geological Society of America Bulletin.
The aeromagnetic anomalies reveal three strands of the fault zone extending from Bremerton to east of Lake Washington. “We’ve known for many years that the Seattle fault exists and is dangerous, but now we have an idea of its location,” Blakely said.
Blakely has also conducted detailed ground magnetic studies of the Seattle fault zone in the Bellevue area and plans to present those results at the Geological Society of America’s Cordilleran meeting May 13-15 in Corvallis, Oregon.
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