We have the unlucky distinction of having three different kinds of earthquakes visit us. We are subject to Shallow, Deep and Subduction earthquakes here in Western Washington in the Seattle region. Each type of earthquake has different characteristics and ‘charms’ associated with it.
Shallow earthquakes are frequent, typically less intense, short in duration with many aftershocks and unlikely to cause tsunamis. Damaging Shallow earthquakes occur every few decades and may be as strong as M7.5.
Deep earthquakes occur in our area about every 10- 30 years, lasting a few seconds to less than a minute with few aftershocks and are unlikely to cause tsunamis. The 2001 Nisqually was an example of this type. Magnitude may be as high as M7.5 but usually less. Typically less damaging than shallow earthquakes of the same magnitude.
Subduction earthquakes occur averaging about 500 years apart. They last for several minutes with strong shaking and will have many aftershocks and will certainly cause tsunamis. They may be as large as M9. The last great Cascadia earthquake occurred on Jan. 26, 1700.
Any of the three types of earthquakes could occur here at any time so it is best to be prepared. You can buy a commercial earthquake emergency pack or make your own. Pre-think now how you will return to home and loved ones if a large earthquake hits the Seattle area today. How will you get home? How long will it take? Highways will be closed; many roads impassable. Stores closed, gas stations closed, medical help unavailable. Do you have water, food and supplies to get home through a disaster area? Its uncomfortable but best to think about his now and do some very basic planning. Do you have some minimum supplies in the car and in the office?