Study: Big Earthquake Near Seattle Could Bring Deadly Landslides
October 22, 2013 by UPI - United Press International, Inc.
SEATTLE (UPI) — The next big earthquake on a fault near Seattle could pose a significant risk to the city from tremor-triggered landslides, seismologists say.
Writing in the Bulletin of the Seismological Society of America, the study authors said the potential damage could be greater than previously thought and beyond the areas currently defined as prone to landslides.
“A major quake along the Seattle fault is among the worst case scenarios for the area since the fault runs just south of downtown,” University of Washington doctoral student Kate Allstadt said.
“Our study shows the need for dedicated studies on seismically induced landsliding.”
Seattle is particularly prone to strong shaking the could create landslides, the researchers said, because it sits atop the Seattle Basin — a deep sedimentary basin that amplifies ground motion and generates strong seismic waves that tend to increase the duration of the shaking.
The last major quake along the Seattle fault in A.D. 900 — long before the city was established, although native peoples lived in the area — triggered giant landslides along Lake Washington, sending entire blocks of forest sliding into the lake, the researchers said.
“There’s a kind of haunting precedence that tells us that we should pay attention to a large earthquake on this fault because it happened in the past,” Allstadt said.