Sooner or later, a massive quake will hit Pacific Northwest

March 17, 2011 

The message bears repeating, over and over again: The Pacific Northwest is home to the same type of massive earthquake that struck northern Japan last week.

Thousands of miles apart, the two regions of the world share a common boundary within the Ring of Fire, the zone of frequent earthquakes and volcanic activity that rings the Pacific Ocean.

Think of this: More than 90 percent of the world’s total earthquakes and 80 percent of the world’s destructive earthquakes happen in the Ring of Fire.

Japan was struck a deadly blow from what is called a subduction zone earthquake, which is a tectonic rupture that occurs when the two crustal plates lock up, then break loose, releasing unimaginable, but very real, forces of energy in the form of an earthquake.

In Japan, the Pacific Plate is sliding under the Eurasian Plate, creating a breeding ground for violent geologic activity. Here in the Pacific Northwest, the Juan de Fuca Plate is sliding under the North American Continental Plate, creating the same template for disaster.

The Cascadia subduction zone off the Washington-Oregon coast last ruptured in 1700, long before millions of people and billions of dollars in roads, bridges and buildings covered the landscape. A repeat of that magnitude 9 earthquake and the tsunami that would accompany it would cause untold property damage and loss of live.

For those who dismiss the liklihood of such a catastrophic event – at least in their lifetime – here’s a quick little math lesson. The geologic record shows that subduction zone earthquakes on the Cascadia fault line occur every 400 to 600 years. The last one was in 1700. The clock is ticking. It’s not a matter of if. It’s a matter of when.

Some are prone to throw up their hands and say: “There’s nothing I can do to prepare for a disaster like the one in Japan.”

That’s the wrong attitude to take. Everyone in South Sound should know what action to take when the earth starts to rumble and shake. If indoors, take cover under a sturdy table or desk, cover your face and head and stay away from glass, windows, outside doors, walls and light fixtures. Stay in place until the shaking stops. If outdoors, move away from buildings, streetlights and utility wires. If you’re in a moving vehicle, stop as quickly as safety allows.

In preparation for the next disaster, every family in South Sound should prepare an emergency disaster plan, complete with extra food, water, a first aid kit, battery-powered radio, flashlights, a home-evacuation plan and an emergency contact outside of earthquake country for family members to leave messages.

Homes and work places alike should be made as earthquake-proof as possible, which means anchoring hot water heaters and bookshelves to walls and computer equipment to desks, securing artwork and other valuables that could come crashing down in an earthquake and moving forward with foundation and chimney repairs that have been delayed far too long.

Residents and visitors along the Washington coast need to know the tsunami evacuation routes that have been marked by emergency management personnel. Take tsunami warnings seriously and act accordingly. Need a reminder why? Just check the footage of the tsunami damage in Japan.

We just passed the 10-year anniversary of the Feb. 28, 2001, Nisqually earthquake. That earthquake, along with similar ones in 1949 and 1965, were deep-seated temblors that are actually the least destructive of the three types of earthquakes known to occur in the Puget Sound region. The other potentially deadly quake would be one near the Earth’s surface that occur on a fault line of the continental plate.

In other words, the region has been relatively lucky in the last several decades to have only experienced deep earthquakes.

Don’t read to much into recent history. Take the risk of a Japan-type earthquake seriously and improve emergency preparedness at home and work. It’s the sensible thing to do.

For more information on how to prepare for the next destructive earthquake, visit www.emd.wa.gov or www.co.thurston.wa.us/em.

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