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Comment by RcouF1uZ4gsC | Hacker News Reader

From that article:

> fema projects that nearly thirteen thousand people will die in the Cascadia earthquake and tsunami.

From the rest of the article, it seems that this estimate of deaths is too low by an order of magnitude. More people died in the Fukushima earthquake, and that is in a country that is probably the most earthquake ready country in the world.

If you only have 15 minutes from the start of the earthquake to when the tsunami rolls in, given the density and the lack of preparation, I could easily see several 100 thousand people perishing if not a million.

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I don’t know about how this would impact the estimates, but the Pacific Northwest differs from Japan in that the largest population centers — Vancouver, Seattle, Portland — are not exposed to the open ocean.

Seattle also rises very quickly from the ocean. Take a look: https://en-us.topographic-map.com/maps/na3/Seattle/

With the exception of the international district, all the low-lying areas are industrial in nature.

"Drumlin" is the fun word for this geology, from what I understand. https://youtu.be/oSSxdogrv1s?t=189

Right, in Oregon the coastal areas mostly rise quite quickly from the beach and are relatively sparsely populated. The more populated areas of Portland, Salem, Eugene, etc are well away from the ocean, so a tsunami is unlikely to kill very many people here.

The population isn't really coastal. There will be a lot of casualties along the coast, but it is sparsely populated. The overall number should be much lower than the Tohoku quake. Some other estimates have the number considerably lower than FEMA's.

That figure comes with a caveat that's mentioned towards the end of the article:

> As for casualties: the figures I cited earlier—twenty-seven thousand injured, almost thirteen thousand dead—are based on the agency’s official planning scenario, which has the earthquake striking at 9:41 A.M. on February 6th. If, instead, it strikes in the summer, when the beaches are full, those numbers could be off by a horrifying margin.

Thirteen thousand sounds like a best case scenario. If it happens 4th of July weekend when a million people are on the beaches all up and down the west coast, that could cause orders of magnitude more fatalities.

If this is the case, it seems like you could get a lot of bang for your buck by building up a beach evacuation infrastructure.

All you really need to do is get inland, and usually not very far.

In this sample evacuation map for Ocean City WA, the higher ground is within half a mile of a good chunk of the coast, and nearly all of the coast is a mile from higher ground. https://www.dnr.wa.gov/Publications/ger_tsunami_evac_oceanci...

All along the Oregon coast are signs indicating where the tsunami impact zone is, and I think there are also alarms in a lot of towns too.

there is never a million people on the oregon coast.

The problem is if the entire west coast adds up to 1 million people at the beach it might make very little difference which state their in. A 7pm July 4th quake resulting in a massive Tsunami would be vastly more deadly than an identical 4am quake the next day.

If there were ever 1 million people heading to the PNW coast collectively, even on 4 July, the PNW would know it. Routes like the 26 out of Portland or the redwood highway in Oregon / California cannot handle that much traffic. The road to Gerlach, NV gets jammed up by Burning Man traffic, so that should give a good estimate of how many people there can possibly be out there.

Also, unlike in California or the East Coast, these are not quick jaunts to the ocean.

You misunderstood, natural disasters don’t care about state lines or even national borders.

It’s likely no one state adds up to 1 million people, but collectively people at in or near pacific ocean in the US, Canada, and Mexico are at risk. So, if you want to understand the risk from such an earthquake you add everyone together.

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