October 23, 2017
SCIENTISTS KNOW THAT A MASSIVE earthquake will one day shake the Pacific Northwest. At some point in the future, pressure building on the Cascadia subduction zone will reach a breaking point, and the Juan de Fuca plate will slide further under the North American plate. It happens roughly every 500 years, and when it does it is going to be big. But earthquake propagation is impossibly complex, so no one knows how much shaking different cities in the region will experience. The last time a subduction zone quake rattled the region, it was January 26, 1700, and all we know about it comes from tree ring data, sediment cores, oral traditions of indigenous peoples living in the area, and records of an “orphan” tsunami in Japan. To understand the inevitable shaking, scientists have produced a new set of simulations of the “Really Big One”.
Image: U.S. Army/Public Domain