By Andrea Watts
For The Daily World
If you happened to see two research vessels off the coast of Grays Harbor this month and wondered what was going on, would you believe earthquake research was being conducted? It turns out the coast off Grays Harbor isn’t just known for its good fishing grounds, it also has a fault that is the centerpiece of several research studies.
Not all earthquakes are equal. There are the long-lasting, magnitude 5-6 earthquakes that occur regularly beneath the Puget Sound, and then there are the sudden megathrust magnitude 9 earthquakes capable of producing the tsunami that in 1700 crossed the Pacific Ocean and destroyed Japanese coastal villages. Along the Washington Coast is a fault capable of producing a megathrust earthquake.
The fault in our backyard is located within the Cascadia Subduction Zone, an area spanning more than 680 miles, from Mendocino, Calif. to northern Vancouver Island. A fault is the contact zone where two tectonic plates collide and scrape against each other. For those of us living on the Washington margin, it’s the younger and heavier Juan de Fuca plate diving or subducting beneath the older and lighter North American plate. Other similar subduction zones are found south of the Alaskan Aleutian Islands and off the coasts of Chile, Indonesia, Japan, and New Zealand. These zones have also experienced megathrust earthquakes, causing extensive damage and producing tsunamis.