By Gordon Williams  

If you live in Washington state, you are most likely familiar with the phrase “the big one.” That refers to the potential for a catastrophic earthquake along the Cascadia Subduction Zone —the major geological fault line that runs down the Pacific coast of North America. When it comes — and quakes along the subduction Zone occur every 300 years or so — the toll in lives and property could be enormous. 

And now, it turns out the fault line is more complex than anyone had supposed. Instead of a single fault, the zone seems to consist of four separate fault lines — each capable of giving birth to a quake. The discovery comes from recent studies of the underwater portion of the fault line. The findings add to the pressure on relief agencies to plan for a response to the big one, whenever it comes. For the record, the last such quake occurred in 1700.  

To explain the situation, you should know that the world rests on vast tectonic plates that float on the earth’s surface. Put most simply, earthquakes occur when two such plates scrape against one another. A subduction zone goes that scenario one better. In the case of the Cascadia Subduction zone, one plate — the North American plate — is sliding over the Juan de Fuca plate, pushing it down.  

Eventually the downward thrust will reach its limits, the Juan de Fuca plate will quit sliding lower and the result will be a “big one”. What happens then is anyone’s guess.  

The quake could cause enormous damage along the coast, with a potential death toll in the thousands. Locally, whole sections of Seattle, Tacoma, Portland and Vancouver would be flattened. The quake could trigger a tsunami strong enough to send a wall of water racing down Puget Sound. Rescue forces trying to reach the scene would be blocked by fallen bridges and blocked highways.   

The new discoveries about the complex nature of the Subduction Zone add a new level of complexity to the disaster planning process.   

Jenny Carkner, who heads the Red Cross disaster response for the Northwest Region (Washington and northern Idaho) understands that her regional responders are likely to need to secure their own homes and families. So, the disaster response would be managed and staffed by Red Cross national headquarters workers who deploy to Washington.  

Damage is expected to be far less in Eastern Washington than nearer to Puget Sound, and there will be a flood of people seeking to escape the worst of the quake by heading east. How well they do in that regard will depend on road and bridge conditions. In the end, many survivors of the quake will be blocked from heading east by broken highways and collapsed bridges. Help will have to come from outside. 

As to what Western Washington is likely look like after the quake, look at the plans prepared by the Kitsap County Department of Emergency Management (DEM). The county is located just across Puget Sound from Seattle. Projections show the county being carved into 27 micro-islands by collapsed bridges and washed-out roads. Plans call for each micro-island to be stocked with emergency supplies to be used in such a situation.  

The obvious question is, what plans can you make to survive the big one and make it through whatever it brings to your area?

The answer, keep doing what anyone living in Washington should be doing, which is preparing to survive a quake. The same plans you make to survive a once-in-300-years catastrophic quake will keep you alive and functioning through the many smaller quakes that hit the state.  

• Keep emergency supplies of food and water handy in case a quake leaves you isolated and cut off from supplies.
• Have lots of flashlights and a battery powered radio, plus lots of extra batteries.
• Keep extra doses of your most-needed medications. Remove heavy objects to lower shelves and use heavy-duty latches to keep closet doors from opening suddenly in a quake.
• Remove any heavy objects that hang over beds.   

Ask your fire department and emergency management for their best advice on enduring an earthquake. What plans do these agencies have for housing and caring for quake victims? Since emergency help after a quake will have to come from local resources, what plans do these agencies have for bringing aid to your community?   

The Big One may not come for years — maybe not within your lifetime — but the more you plan ahead, the better your chances of making it through the big one, whenever it does come.