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11-13-2012, 02:39 AM
Join Date: Feb 2008
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Originally Posted by CCF23 View Post
Yeah, looks like we'd get it a bit, but it seems as if the lower mainland, for the most part, has a lot blocking it to help protect it from anything catastrophic.

Aberdeen, Washington looks like it'd be about the worst place to be.
Something people often don't talk about is a under water landslide of the Fraser river delta out in the Georgia straight. It can slide at any point in time, however during a major earthquake the odds of it sliding go up astronomically. The tsunami produced would dwarf anything a subduction earthquake could produce, it could be up to a 100 meters in height depending on the volume of built up sediment that slides. The main force of the wave would be directed at the gulf islands and pretty much wipe them out, much of the force would reflect back across the straight of Georgia and still be in the 10's of meters in height by the time it reached Richmond, Vancouver, West Vancouver, North Vancouver. It would also travel up the Fraser River and threaten everyone probably as far as Hope depending on the initial size of the wave.

As far as the wave that would result from the subduction quake it would take over 2 hours to reach the lower mainland, but it could still be high enough to breach the dykes around Richmond and damage anything not behind one. If we are in a high tide or a low tide obviously makes a world of a difference.

I would not like to imagine a combination of a 9+ earthquake, a large tsunami and a underwater landslide of the Fraser delta, in this case Richmond would be in serious trouble along with all other sea level communities.
*keep in mind that a 9+ subducton earthquake is also strong enough to drop the ground level by a meter or two, something that is for what ever reason often not taken in to account when measuring tsunami risks. Two things happen, A) the actual plate drops, B) soft soil compacts and water gets squeezed out of it.

Last edited by 0123456789*: 11-13-2012 at 02:44 AM.
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