6 ms·

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

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

edgyswingset 11y ago
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.
- saintgimp 11y ago
  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.
  - deleted 11y ago
    [deleted]
    - olefoo 11y ago
      Large parts of downtown and the area between Queen Anne and Capitol Hill ( where the Amazon campus is ) are built on fill, and are likely to be subjected to liquefaction in a major seismic event. It's entirely possible that whole sections of Capitol Hill could slide into downtown too. The hills shake and the mountains dance, and then comes the tsunami; this sounds much more exciting to read about than live through.
      - nkrumm 11y ago
        Here's a map of liquefaction risk in King county: http://your.kingcounty.gov/dnrp/library/water-and-land/flooding/local-hazard-mitigation-plan-update/liquefaction-hazard-map.pdf http://your.kingcounty.gov/dnrp/library/water-and-land/flood...
        pnathan 11y ago
        Thanks! I was going to be googling for that shortly. :-)
- facepalm 11y ago
  Tsunamis are not like normal waves. I think they might be more like a really big rise of the tides.
  - chrismcb 11y ago
    Tsunamis are in fact a lot like waves, just real big ones. Tsunamis move quickly, a tide does not.
    - facepalm 11y ago
      I meant in the amount of water shifted - so you don't simply break a Tsunami like a wave, the water just keepscoming.
- dgraunke 11y ago
  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 http://www.pmel.noaa.gov/pubs/PDF/wals2794/wals2794.pdf
- soperj 11y ago
  Narrow straights would actually increase the damage, as was the case in the '64 Port Alberni(vancouver island) tsunami.
- pchristensen 11y ago
  Tsunami inundation maps: http://wa-dnr.s3.amazonaws.com/Publications/ger_tsunami_inundation_maps.pdf 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.
civilian 11y ago
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.
- deegles 11y ago
  Could a tunnel even survive an earthquake above 8.5?
  - CamperBob2 11y ago
    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.
  - WildUtah 11y ago
    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.
    - CamperBob2 11y ago
      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.
- 11y ago
jsprogrammer 11y ago
"We take earthquake safety seriously, but earlier today..."
InclinedPlane 11y ago
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.

edgyswingset 11y ago

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.

saintgimp 11y ago
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.
- deleted 11y ago
  [deleted]
  - olefoo 11y ago
    Large parts of downtown and the area between Queen Anne and Capitol Hill ( where the Amazon campus is ) are built on fill, and are likely to be subjected to liquefaction in a major seismic event. It's entirely possible that whole sections of Capitol Hill could slide into downtown too. The hills shake and the mountains dance, and then comes the tsunami; this sounds much more exciting to read about than live through.
    - nkrumm 11y ago
      Here's a map of liquefaction risk in King county: http://your.kingcounty.gov/dnrp/library/water-and-land/flooding/local-hazard-mitigation-plan-update/liquefaction-hazard-map.pdf http://your.kingcounty.gov/dnrp/library/water-and-land/flood...
      - pnathan 11y ago
        Thanks! I was going to be googling for that shortly. :-)
facepalm 11y ago
Tsunamis are not like normal waves. I think they might be more like a really big rise of the tides.
- chrismcb 11y ago
  Tsunamis are in fact a lot like waves, just real big ones. Tsunamis move quickly, a tide does not.
  - facepalm 11y ago
    I meant in the amount of water shifted - so you don't simply break a Tsunami like a wave, the water just keepscoming.
dgraunke 11y ago
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 http://www.pmel.noaa.gov/pubs/PDF/wals2794/wals2794.pdf
soperj 11y ago
Narrow straights would actually increase the damage, as was the case in the '64 Port Alberni(vancouver island) tsunami.
pchristensen 11y ago
Tsunami inundation maps: http://wa-dnr.s3.amazonaws.com/Publications/ger_tsunami_inundation_maps.pdf 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.

civilian 11y ago

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.

deegles 11y ago
Could a tunnel even survive an earthquake above 8.5?
- CamperBob2 11y ago
  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.
- WildUtah 11y ago
  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.
  - CamperBob2 11y ago
    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.
11y ago

jsprogrammer 11y ago

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

InclinedPlane 11y ago

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.