How the Pacific Northwest Should Prepare for the Cascadia Tsunami

In the wake of last months Tsunami disaster in Japan, people in the Pacific Northwest have a renewed interest in the possibility of a similar disaster happening here.  I mis-speak.  It is not a possibility of happening in the Northwest, it’s a certainty.  The only question is, when?

Sitting 90 miles of the coast of Oregon and Washington is the Cascadia subduction zone, where the Juan de Fuca plate dives under the North American plate.  This fault has a geologic history of producing megathrust earthquakes like clockwork, every 300-600 years.  The last such earthquake took place on January 26, 1700.  We have just entered the window of danger.

When Cascadia cuts loose again, residents and visitors along the coast will have at most 15 minutes to seek high ground before the first tsunami waves arrive.

Unlike Japan, there are no major metropolitan centers located on the coast of Washington and Oregon.  In most places the coastal range plunges steeply into the sea, limiting the amount of damage that a tsunami can do.  But there are low lying sea side communities.  The one that gets the most attention is usually the community of Seaside, on Cannon Beach.  This popular weekend destination for Portland inhabitants is fully aware that it’s in the crosshairs of Cascadia, and tsunami evacuation routes are very plainly marked.  Fortunately, most of Cannon beach is within a mile of high ground, and any healthy person should be able to make it to safety on foot.

Unfortunately, there are other, more vulnerable communities than Seaside.  In Washington, Long Beach, Westport and Ocean Shores are three communities which will be erased from the map by a tsunami.  These communities have no high ground in easy walking distance, and very limited routes of access and evacuation.  The loss of life in these communities could easily be as high as 90%. 

Studies are underway to engineer vertical evacuation routes.  The idea is to literally build emergency buildings high enough and robust enough to withstand a tsunami.  This idea is a fallacy and would be a stupendous waste of money and resources for very little benefit.  For one thing, there is no way to know if such a structure could actually stand up to a tsunami after having weathered a severe earthquake.  There is only so much that modeling can do to predict how a building will behave in such an event.  The other problem with this plan is one of sheer logistics.  How can you get everyone to reach said building, and inside to a safe level, in the limited amount of time available? 

Let’s look at facts:  When this happens, people are going to do stupid things.  Many people are going to try to evacuate by car.  This will cause tremendous traffic jams, and traffic will not move.  Many people will not know what to do.  There will be injured people unable to move, buried in collapsed houses.  Streets will be filled with refugees heading for high ground, but there will always be some idiot who lost a family member going the wrong way.

If you have a vertical evacuation facility, how many people know where it’s at?  It’s easy to get to high ground when hills are available – you just pick a direction and go as fast as you can.  But with everyone attempting to converge on a single building, there will be mobs as people fight to get in first.  The entrances will be jammed.  People are going to be trampled, and many will die waiting to get in when the first wave comes.

Without such a facility, people in communities with no high ground handy should grab hold of a loved one and make their peace with God, because they’re going to die.  With such a facility, there’s still a high probability they won’t be able to reach it, or having reached it, they won’t be able to get in because of the crowd.

There is a better solution.  Tsunami pods.

I envision a tsunami pod as similar to the lifeboat on an oil rig.  These lifeboats are self-contained.  You get in them; you strap in and release them.  They ride down rails and literally plunge into the sea, submerging completely.  They’re shaped so that the plunge will carry them underwater quite a distance before they pop back to the surface.

Now we don’t need anything that fancy for a tsunami pod.  What we need is something that will float, stay more or less upright, is watertight, submersible, and built strongly enough that it can withstand crush pressures caused when it’s swept up in a debris flow and pushed and battered along the path of the Tsunami.  It could be as small as a single person, or maybe even as large as a rail car – in fact, rail tanker cars may make a good hull for such a pod.  There should be restraints for occupants, because it’s going to be a rough ride. 

Working on a basic, simple design, these tsunami pods could be mass produced and distributed throughout population centers and at-risk tourist areas.  In the event of a major earthquake – and when Cascadia cuts loose, people on the coast will have no doubt in their mind – you make your way to the nearest tsunami pod and get in.  Everyone gets in and straps themselves in, and the last guy closes the hatch either when the pod is full or when the water starts to rise.

Notices in the pods will clearly instruct occupants to stay in the pod for at least 6 hours.  There will be multiple waves, and the first one may not be the biggest.  After 6 hours, all pods will activate an emergency homing beacon, so that search and rescue teams can find them.  Some pods will be buried in debris.  Others will be washed out to sea and be floating off the coast.  But the beauty of this system is that most people in these pods will be bruised, battered, but alive!  You could build a huge number of these pods for the price of a single vertical evacuation facility. 

In terms of investment for life saved, this is a far better way to prepare for the coming tsunami.