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I live in PDX. There are about a dozen bridges. If even one were left standing over the Willamette it wouldn’t be too bad — at least families could reunite. The

I live in PDX. There are about a dozen bridges. If even one were left standing over the Willamette it wouldn’t be too bad — at least families could reunite. There are a lot of boats on the river too, and it’s not wide or strong, so people could get ferried across. Regular commute and business traffic would disappear, of course. None of those things are true for the Columbia River separating Oregon and Washington. There aren’t many bridges and they’re very long. The river is non-trivial to cross. That would be a big mess.

finnh 3y ago
oooof I'm imagining having to drive east on 90 to cross the Columbia at Vantage just to drive from Seattle to Portland... (many bridges would have to go down for this to be the only way, of course)
- cossatot 3y ago
  Earthquake-induced landsliding is common enough that neither 90 or 14 may be open after an M 9 event, especially during the rainy season.
jasonwatkinspdx 3y ago
Yeah, we'd need to borrow ferries from somewhere. But if it's the big one, Puget sound is also probably a mess so there goes the obvious option.
- lotsofpulp 3y ago
  What would happen to the sound in the event of an earthquake? I figure equipment to unload boats might be damaged, but the boats themselves should be able to come and go as before, no?
  - jasonwatkinspdx 3y ago
    The cascadia subduction zone extends from north of Vancouver island to NorCal. The sound is expected to see 8+ on the Richter scale. So they'll probably have too many of their own problems to lend help to Portland.
    - ianburrell 3y ago
      BTW, the quake won't be that strong at Seattle and Portland. The subduction quake could be up to magnitude 9 but that is off the coast and over the mountains. I have seen estimates of magnitude 7-7.5 shaking in Portland. However, it will be 5 minutes of shaking which will liquefy soils. The result is that most buildings in Portland will survive. Only unreinforced masonry and liquefaction areas will have serious damage. The quake is survivable, the problem is infrastructure wasn't built with quake in mind.
briffle 3y ago
There are way more bridges than that. Those are just the major ones. Marion county will essentially be 17 islands because so many small bridges will buckle
dredmorbius 3y ago
One thing the San Francisco Bay Area rediscovered after the Loma Prieta earthquake in 1989 was that ferry services are highly resilient in the aftermath of major seismic events. The Oakland-San Francisco Bay Bridge was damaged in the quake, though other crossings: the Golden Gate, Dunbarton, San Mateo, Richmond-San Rafael, Carquinez Strait, and Martinez bridges, all survived intact. Suspension bridges are also far more resilient than fixed (truss, viaduct) spans, though several of the structures that did survive are fixed designs.
- brewdad 3y ago
  Seattle might be fine but Portland doesn’t have any ferries. Washington’s ferry stock is rapidly aging and not being replaced quickly enough.
  - dredmorbius 3y ago
    The San Francisco Bay Area had few ferry services in 1989 as well. Which is why word "rediscovered" was working hard in my earlier comment, rather than merely loitering as some may have suspected. Whilst there was some ferry service prior to the quake, existing route service was expanded greatly, and new routes added: "Water Emergency Transportation Authority | Draft Final Transition Plan" The Alameda/Oakland Ferry Service (AOFS) was started after the Loma Prieta earthquake on October 17, 1989, in direct response to the collapse of a section of the San Francisco-Oakland Bay Bridge and the nearly month-long closure that followed. the evening of the earthquake, private excursion vessel operators moved people across the Bay. By the following Monday, emergency funding had been secured and ferries were being operated between the San Francisco ferry Building, Oakland’s Jack London Square, and a temporary terminal at the foot of Main Street in Alameda. After the Bay Bridge was reopened, ferry service operated by Red and White Fleet and sponsored and funded by the city of Alameda, Port of Oakland, MTC and CalTrans was continued.... Vallejo’s current-day ferry service started in 1986 when Red & White fleet started limited commuter ferry service to and from San Francisco and midday service to marine world, which had just opened.... After the Loma Prieta earthquake in 1989, ferry ridership increased dramatically and remained high for several years. In 1994, the city of vallejo purchased their first high-speed ferry boat... <https://weta.sanfranciscobayferry.com/sites/weta/files/weta-public/publications/TP0618909.pdf https://weta.sanfranciscobayferry.com/sites/weta/files/weta-...> A more general history at Wikipedia notes that Oakland, Alemeda, Berkeley, Richmond, and Treasure Island service all post-date the Loma Prieta quake: <https://en.wikipedia.org/wiki/Ferries_of_San_Francisco_Bay https://en.wikipedia.org/wiki/Ferries_of_San_Francisco_Bay>

finnh 3y ago

oooof I'm imagining having to drive east on 90 to cross the Columbia at Vantage just to drive from Seattle to Portland... (many bridges would have to go down for this to be the only way, of course)

cossatot 3y ago
Earthquake-induced landsliding is common enough that neither 90 or 14 may be open after an M 9 event, especially during the rainy season.

jasonwatkinspdx 3y ago

Yeah, we'd need to borrow ferries from somewhere. But if it's the big one, Puget sound is also probably a mess so there goes the obvious option.

lotsofpulp 3y ago
What would happen to the sound in the event of an earthquake? I figure equipment to unload boats might be damaged, but the boats themselves should be able to come and go as before, no?
- jasonwatkinspdx 3y ago
  The cascadia subduction zone extends from north of Vancouver island to NorCal. The sound is expected to see 8+ on the Richter scale. So they'll probably have too many of their own problems to lend help to Portland.
  - ianburrell 3y ago
    BTW, the quake won't be that strong at Seattle and Portland. The subduction quake could be up to magnitude 9 but that is off the coast and over the mountains. I have seen estimates of magnitude 7-7.5 shaking in Portland. However, it will be 5 minutes of shaking which will liquefy soils. The result is that most buildings in Portland will survive. Only unreinforced masonry and liquefaction areas will have serious damage. The quake is survivable, the problem is infrastructure wasn't built with quake in mind.

briffle 3y ago

There are way more bridges than that. Those are just the major ones. Marion county will essentially be 17 islands because so many small bridges will buckle

dredmorbius 3y ago

One thing the San Francisco Bay Area rediscovered after the Loma Prieta earthquake in 1989 was that ferry services are highly resilient in the aftermath of major seismic events. The Oakland-San Francisco Bay Bridge was damaged in the quake, though other crossings: the Golden Gate, Dunbarton, San Mateo, Richmond-San Rafael, Carquinez Strait, and Martinez bridges, all survived intact. Suspension bridges are also far more resilient than fixed (truss, viaduct) spans, though several of the structures that did survive are fixed designs.

brewdad 3y ago
Seattle might be fine but Portland doesn’t have any ferries. Washington’s ferry stock is rapidly aging and not being replaced quickly enough.
- dredmorbius 3y ago
  The San Francisco Bay Area had few ferry services in 1989 as well. Which is why word "rediscovered" was working hard in my earlier comment, rather than merely loitering as some may have suspected. Whilst there was some ferry service prior to the quake, existing route service was expanded greatly, and new routes added: "Water Emergency Transportation Authority | Draft Final Transition Plan" The Alameda/Oakland Ferry Service (AOFS) was started after the Loma Prieta earthquake on October 17, 1989, in direct response to the collapse of a section of the San Francisco-Oakland Bay Bridge and the nearly month-long closure that followed. the evening of the earthquake, private excursion vessel operators moved people across the Bay. By the following Monday, emergency funding had been secured and ferries were being operated between the San Francisco ferry Building, Oakland’s Jack London Square, and a temporary terminal at the foot of Main Street in Alameda. After the Bay Bridge was reopened, ferry service operated by Red and White Fleet and sponsored and funded by the city of Alameda, Port of Oakland, MTC and CalTrans was continued.... Vallejo’s current-day ferry service started in 1986 when Red & White fleet started limited commuter ferry service to and from San Francisco and midday service to marine world, which had just opened.... After the Loma Prieta earthquake in 1989, ferry ridership increased dramatically and remained high for several years. In 1994, the city of vallejo purchased their first high-speed ferry boat... <https://weta.sanfranciscobayferry.com/sites/weta/files/weta-public/publications/TP0618909.pdf https://weta.sanfranciscobayferry.com/sites/weta/files/weta-...> A more general history at Wikipedia notes that Oakland, Alemeda, Berkeley, Richmond, and Treasure Island service all post-date the Loma Prieta quake: <https://en.wikipedia.org/wiki/Ferries_of_San_Francisco_Bay https://en.wikipedia.org/wiki/Ferries_of_San_Francisco_Bay>