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Hi Roger –

Thanks for your question. You are right, the question is not “if,” it is “when.”

That Cascadia Fault will rupture again (as it has done dozens if not hundreds of times in the past). On average, it ruptures as a huge megathrust quake only every 500 years or so, which is why we have not had a big quake here in recorded (meaning our written) history. But the natives have oral accounts of the quakes, and the last big quake here (Jan. 26, 1700) sent a huge tsunami wave that was recorded in written documents in Japan. So the last (large, megathrust) quake here was in 1700, which is 312 years ago. The next one could be tonight, or not for another 200 or more years – we simply do not know.

The impact it will have on Vancouver Island depends in part where the epicentre is this time (it could be very close, just offshore of/below Tofino, or it could be way down the coast off Oregon). Obviously, the closer it is, the worse the shaking will be. Either way, the shaking will last for several minutes. If the epicentre is down near Oregon there will probably be a lot of structural damage here – but if it is close, the damage will probably be severe (think the photos we saw from Japan – that’s the size of quake we are talking about).

What you need to know depends a lot on where you are planning to live. The outer coast is closer to the fault than the inner coast is, so both shaking from the quake and any tsunami damage will be worse there. If you are very close to the water, within the potential tsunami inundation zone (much of west coast communities such as Tofino, Ucluelet, Port Alberni, and probably parts of Victoria, although I’ll admit I have not researched the specific impact to Victoria much) then you need to be prepared to move out of that inundation zone very quickly after the earthquake shaking stops (remembering you probably will not be able to drive the roads, and that you or family/friends may be injured). The devastation and destruction will be severe and widespread (through much of coastal BC, WA, OR) so, depending upon where you are living and how cut off your roads are after the quake (from landslides etc) you may not receive outside aid for a long time – so you should try to figure out what is realistic for where you live, and have a large supply of food, and water (or, probably better, water purification tablets – we usually are not short of actual water out here!) and fuel for cooking (e.g. extra propane for your gas BBQ, or camp stoves with lots of spare fuel) around (to last weeks? or perhaps more? depending upon where you live and what you can reasonably expect for access to aid). I have moved away from Tofino now – but if I was still there, personally I would plan for a couple of months of minimal supplies getting in (look what happened in Japan…).

I have written a lot about this (some of it when I was really frustrated by Tofino’s lack of foresight and realistic planning… and the tone of my articles reflects that). You can read much of my detailed info in these articles, especially the numbered points in the “Whatever” article:
http://tofinoresidents.wordpress.com/category/emergency-preparedness/earthquake/

I would suggest that the first thing you do is find out more about the predicted impacts and planning in the community that you are moving to. I would suggest NOT moving into a home that is within the potential inundation zone (your community should have some sort of map, somewhere, showing how high the wave could possibly reach – and remember that, in Japan, it came higher that the predictions, so err on the side of caution). I would suggest finding out what your new community’s plan is, and assessing for yourself how appropriate and complete it is – some communities have excellent knowledge and planning, and some communities are in la-la land about this. Then figure out what you need to do, personally, on top of the community plan, in order to feel safe.

It is more likely that it will NOT come within our lifetimes (say, next 50 years) than that it WILL come. But it is certain that it will come some day – and, when it does, it will be very very bad. I don’t think people should live in fear, by any means. But I think that it is important to be informed, in advance (you don’t want to be figuring out this stuff once it hits!), and that you get yourself as prepared as you possibly can.

Jackie