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Comment by sharkweek | Hacker News Reader

Well this article at least justifies that perhaps we don't need to replace the viaduct after all if everything is going to get destroyed anyways!

While my fear of "the big one" doesn't keep me up at night, Seattle is going to be a classic example of "we should have known this was going to happen!" after a sizable earthquake costs substantial life at some point in the future. But this article does seem to stretch itself into making me think that nothing can really be done. It's not going to be realistic to establish safeguards against an 8.5+ if it/or the subsequent tsunami is going to flatten the city west of I-5

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The viaduct's collapse in the next big earthquake and the ~80 lives it'll take is the _reason_ we're building something as a replacement! Granted, Bertha is a huge fuckup.

A MBA in my python night class said that one approach to the viaduct problem would be to: fund a "victims of the viaduct" fund, today, with a couple million. And then pass a law that the compensation for families of the victims is limited to what's in the fund. It is appealing in a weird evil way.

Could a tunnel even survive an earthquake above 8.5?

The purpose of the tunnel is to provide a better view of Puget Sound for real estate development, not to provide any sort of substitute for the viaduct. We will lose significant traffic capacity and downtown accessibility when the viaduct comes down, tunnel or no tunnel.

Engineers have told us that the tunnel will be safer in an earthquake, but then, essentially everything those engineers have told us has been straight out of the Brothers Grimm.

Yes. Japan engineers tunnels -- one longer than the Chunnel -- to survive 9+ earthquakes and they do. BART was undamaged by the Loma Prieta quake that brought down the Bay Bridge and the Oakland freeway.

The length of the tunnel doesn't have much to do with earthquake survivability, beyond the obvious linear scale factor. What the tunnel is tunneling through has a lot to do with it.

Seattle's geology is somewhat different from any of the usual cited examples, as we've learned by watching everyone from journalists to politicians to engineers stand around with dumbfounded looks while the Bertha saga unfolds.

>A MBA in my python night class said that one approach to the viaduct problem would be to: fund a "victims of the viaduct" fund, today, with a couple million. And then pass a law that the compensation for families of the victims is limited to what's in the fund.

What exactly is the "viaduct problem"?

It's going to collapse in the next big earthquake.

//edit: and here's a simulation: https://www.youtube.com/watch?v=hos_uIKwC-c

That's what I assumed, but I didn't (and still don't) see how setting up a limited liability fund for future victims would prevent what is shown in that simulation.

The more cynical/realistic problem is "dealing with the aftermath of the collapse", and the fund helps keep some of the costs from overrunning.

You could do the same after the fact.

It's a harder sell politically to cap compensation to what's in the fund after the fact.

I don't know if this is what the MBA was going for, but the idea might be -

Setting up the compensation fund cements the idea that the disaster is a 'when', not 'if'. Putting a small cap on compensation signals to people - if you're a victim, you might only get this amount of money. The overall effect being that people are actually motivated to vote for measures to fix the problem. e.g., I know I'll only get compensated for a small amount, thus, I want to make sure it's less likely I'm victimized.

Well there goes my favorite hotdog stand...

I'm sure he thought that was a clever solution.

Except that every time even one direction of the viaduct is closed during rush hour (due to an overturned semi or whatever) traffic grinds to a complete halt throughout the entire city.

That sounds like a decent justification for just continuing to use it until it collapses on its own due to disrepair!

I don't think a tsunami is going to flatten the city. A wave has a lot to go through (peninsulas, narrow straights, etc) before it could reach the city, all of which would likely lessen its impact significantly. Where the area will get hit hard, though, is liquifaction and landslides.

There will be significant damage from water all around inland Puget Sound, though I agree not on the scale of the full-blown tsunami on the coast. Everything is going to shift 30 to 100 feet west over the course of a couple minutes - the water in Puget Sound is going to slosh around like crazy.

Tsunamis are not like normal waves. I think they might be more like a really big rise of the tides.

Tsunamis are in fact a lot like waves, just real big ones. Tsunamis move quickly, a tide does not.

I meant in the amount of water shifted - so you don't simply break a Tsunami like a wave, the water just keepscoming.

Yeah, and the Elliot Bay tsunami hazard map[1] is a nice reminder that most of Seattle is up some steep hills (including flat areas like SLU). The hazard map models a 7.3 earthquake on the Seattle fault, which is tiny compared to a 9.0 in the subduction zone, but also doesn't have to travel through all those narrows straits and turns.

[1] http://www.pmel.noaa.gov/pubs/PDF/wals2794/wals2794.pdf

Narrow straights would actually increase the damage, as was the case in the '64 Port Alberni(vancouver island) tsunami.

Tsunami inundation maps: http://wa-dnr.s3.amazonaws.com/Publications/ger_tsunami_inun...

For Seattle, it's south of Downtown, Pioneer Square, the Duwamish industrial areas, and Interbay.

But the density of (destroyed) infrastructure and loss of power/water/sewer would be a much bigger problem citywide.

The viaduct will collapse even in a fairly moderate earthquake. A magnitude 7 quake that was closer to seattle might easily bring it down, for example.

"We take earthquake safety seriously, but earlier today..."

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