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Multifault earthquake threat for Seattle region revealed by mass tree mortality

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Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#51

Post by btilly »

jandrewrogers wrote: post #47
imbusy111 wrote: post #8

Cascadia Subduction Zone[1] is why I never considered living in Seattle/Portland once I found out about it. Funny, cause I live in the SF Bay Area, where the earthquakes are frequent, but they can never reach the magnitude of what's possible by the Cascadia Subduction Zone. [1] https://en.wikipedia.org/wiki/Cascadia_subduction_zone

The fault is at least 150 miles from Seattle proper, the city will not receive the full brunt of the earthquake. Tsunamis are strongly mitigated by the geography of Puget Sound — the biggest tsunami threat is actually the Seattle fault. By contrast, the San Andreas fault literally runs through the middle of the Bay Area.

Let's see.

The Cascadia quake is 100x as big. I'm at 1/3 the distance from the San Andreas fault. Guess who gets the larger earthquake?

Add to that the fact that I grew up in Victoria. All of Vancouver Island is a subduction zone during a Cascadia earthquake. Sadly, that means that a good chunk of what I knew growing up winds up under water. Seattle may fare better, but my home town does not.

Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#52

Post by rapind »

asveikau wrote: post #19
dataflow wrote: post #13

Earlier quoted context omitted.

> Funny, cause I live in the SF Bay Area, where the earthquakes are frequent, but they can never reach the magnitude of what's possible by the Cascadia Subduction Zone. What makes you think a big one ("The Big One") isn't going to hit the Bay Area?

I don't think they're saying that. But from what I recall reading, the big one that hits Seattle will exceed the big one that hits the Bay. Seattle's big ones are higher magnitude but less frequent. Iirc it's also likely the 9.0 that hits Seattle won't be in most of our lifetimes. The last really big one was before Europeans arrived.

Rainier will erupt first and the mudslide will wipe out all those houses built on the last mudslide.

Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#53

Post by shostack »

Stratoscope wrote: post #40
imbusy111 wrote: post #8

Cascadia Subduction Zone[1] is why I never considered living in Seattle/Portland once I found out about it. Funny, cause I live in the SF Bay Area, where the earthquakes are frequent, but they can never reach the magnitude of what's possible by the Cascadia Subduction Zone. [1] https://en.wikipedia.org/wiki/Cascadia_subduction_zone

My mom was a Red Cross nurse who worked in the relief effort after the 1964 Good Friday earthquake and tsunami that devastated Anchorage and areas as far south as Crescent City, California. It was magnitude 9.2, the second largest in recorded history. The photos she brought back were quite something. I may still have them somewhere, but in the meantime there are plenty online. LIFE.com has a remarkable collection: ht…

Those numbers, while sad, are surprisingly low compared to other causes of death.

Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#54

Post by mateo- »

tony_cannistra wrote: post #23

A particularly crazy thing I learned from some friends who I know who work in this field is that they use underwater hydraulic chainsaws (!) to sample some of these trees. https://www.stanleyinfrastructure.com/products/underwater-ch... The field work in general seems very wet for this kind of research. (my partner did lots of it for her graduate work)

that 3rd pic could be a black metal album cover

Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#55

Post by diogenes4 »

adrianpike wrote: post #49
diogenes4 wrote: post #46

Earlier quoted context omitted.

According to https://www.sfchronicle.com/projects/2023/bay-area-earthquak... vs https://www.newyorker.com/magazine/2015/07/20/the-really-big... you're looking at two orders of magnitude difference in terms of the estimate of people affected. I'm not sure what led to the difference but that's striking.

That New Yorker article goes viral every few years - it's a well written piece and spins a great yarn, but there's some significant hyperbole and it's sources don't quite back up the claims. Yes, a 9.x will be devastating. No, everything west of i-5 will not be toast.

> it's sources don't quite back up the claims.

I'll admit that FEMA isn't exactly cited in a way that's possible to corroborate, but presumably they're estimating a worst-case scenario and not a median- or average-case scenario. That might explain some of the large divorce in figures.

Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#56

Post by jandrewrogers »

elliotec wrote: post #38
ksenzee wrote: post #30

Earlier quoted context omitted.

On the other hand, Seattle is one of the best places in the world to ride out climate change, which is 100% happening, and happening already. It’s all a numbers game.

Do you have a source for this? What is "best" in this context?

I don’t have sources readily available but I have looked at several climate change projection models for the US in the past to answer similar questions. There are a handful of locales in the US where the local climate doesn’t change much under most models and parameters. They behave almost like fixed points in a mathematical sense. Some of these fixed points are not anywhere you’d likely want to live, so that might not help much.

However, the Seattle region is one, and it already has a pleasant temperate climate. IIRC, the main expected change is that it will get more sun in the winter months, which would address the main criticism of Seattle’s weather.

Of course, these models could be wildly off, but to the extent we have such models Seattle is in an enviable position. While there are some regions that look like they will change for the better e.g. some arid regions will get substantially more rain, it is hard to predict the true impact of that change on those regions — that outcome might come with significant trade offs.

Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#57

Post by rconti »

mvdtnz wrote: post #41
Axsuul wrote: post #36

Earlier quoted context omitted.

And SF isn't?

I'm no expert on the region but aren't people in California forever whining about heat waves and water shortages?

Man, I moved from Seattle to the Bay Area and in the intervening 20 years it sure seems like summers in the PNW have gotten hotter than they are down here.

Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#59

Post by callalex »

iancmceachern wrote: post #45
mvdtnz wrote: post #41

Earlier quoted context omitted.

I'm no expert on the region but aren't people in California forever whining about heat waves and water shortages?

Water shortages are largely in the central valley and Southern California. Sf gets its water from Hetch Hetche, clean hydro power too. SF is a very different place in a lot of ways from the rest of California, and the US in general.

Yes but that aqueduct is hundreds of miles long and goes through the Central Valley. Once the water wars begin, that situation could change rapidly.

Re: Multifault earthquake threat for Seattle region revealed by mass tree mortality

#60

Post by notyourwork »

Axsuul wrote: post #36
ksenzee wrote: post #30

Earlier quoted context omitted.

On the other hand, Seattle is one of the best places in the world to ride out climate change, which is 100% happening, and happening already. It’s all a numbers game.

And SF isn't?

No, it isn't.
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