The Nightmare Quake that Seattle May See

A 9.0-magnitude earthquake would devastate Seattle and Portland, and it might be more likely that you think. For the past 320 years, the Juan de Fuca plate along the Cascadia Subduction Zone has been slowly sliding under the North American plate in a process called subduction, leaving the possibility for one of the largest earthquakes ever known. Unlike other subduction zones, however, these plates have been anchored together in an embrace of death by a magma plume (superheated magma rising from the core), allowing for an unheard amount of energy to build up. This earthquake, nicknamed the “Cascadia Megaquake,” has been a constant shadow looming over the whole West Coast. One primary reason why the earthquake would be so devastating is the large tsunamis that would wreak havoc on Washington, Oregon, and California. The epicenter would be far out from the coast, so shaking would be less fierce at the cities, but all-out in the ocean. The second and more obvious factor is the shaking itself. Tremors would cause soil liquefaction, a process when water seeps out of the ground and “sucks in” buildings and other large structures . Additionally, it would cause buildings to collapse, especially in the Seattle area where a lot of buildings aren’t strong enough to withstand even the 6.2 magnitude Nisqually Quake from 2001 and suffered significant damage. 

Moreover, Seattle is special. It’s located in a bedrock basin. If you’ve ever shaken a bowl of water, you probably noticed how the waves bounce around. The Puget Sound is susceptible to more persistent and intense shaking because of the seismic waves sloshing around in the bowl like fruit punch. This longer shaking would cause bridges to collapse and pipelines to sever, cutting off water, transportation, gas, electricity, and more vital supplies to the Northwest.

Scientists predict that there is a whopping one in five chance that it will occur in the next 50 years! That’s more likely than rolling a 6 on a die the first time. It sounds hopeless, but there is a way to minimize damage: preparation. By organizing an earthquake kit, an evacuation plan, and more, you can help lessen the effect of this nightmare on your family. To learn more, the full preparation list can be found at ready.gov/earthquakes.