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Multifault earthquake threat for Seattle region revealed by mass tree mortality

science.org

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

#91

Post by soultrees »

cossatot wrote: post #78

I wasn't involved in this study, but I wrote the study that estimated the magnitude of this earthquake[0]. In case anyone is interested, usually the magnitudes of 'paleoearthquakes' (historic/prehistoric earthquakes discovered by finding evidence of old ground deformation) are estimated by relating the measured offset of the earth's surface or a rock/dirt layer across the fault line to the earthquake magnitude throug…

How do you go about collecting the data for these studies? Is it core sampling? And if so how many cores would you need to get a good reading?

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

#93

Post by mnky9800n »

DoreenMichele wrote: post #82
doublerebel wrote: post #7

Everyone in the Seattle region is thinking about earthquakes since we just felt the 4.3 quake on Sunday! https://www.seattletimes.com/seattle-news/environment/small-...

I can't readily find a source, but there was another one some weeks back of around 4.0. I can't decide if these are good news making a big quake less likely or foreshadowing of a big quake coming.

There is little evidence that earthquakes come as precursors to larger earthquakes. Most papers reporting such things have selection bias since they are written after the big earthquake occurred.

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

#94

Post by isoprophlex »

To date these Puget Sound samples with a second, independent method, we analyzed individual tree-ring sequences for a jump in annual radiocarbon concentrations associated with an extreme solar proton event (30, 31). This rapid, large magnitude (~10‰) radiocarbon excursion between the years 774 and 775 CE is recorded globally in tree cellulose and can therefore be used as an exact geochronological anchor point (30, 32, 33)

They found more exact dates because a massive solar storm in the past changed carbon isotopes worldwide, which is reflected in tree rings that grew during the storm. That's incredibly cool.

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

#95

Post by elliotec »

meowkit wrote: post #63
elliotec wrote: post #38

Earlier quoted context omitted.

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

This is not something with a "source" or a real academic answer. There are too many variables and long tail events. Survival in some of the worst case climate change scenarios involves moving away from the equator where crop failure and extreme heat will occur. It involves having good access to water, and ideally farmland as wars over resources and refugee migration accelerate. Martial law of some kind would become a…

This all sounds reasonable but also anecdote. I'm curious if there are any analyses, studies, or anything other than PNWers' HN comments backing claims like these.

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

#96

Post by fransje26 »

DoreenMichele wrote: post #83
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.

I wish we were less focused on moving to where we can survive this mess and more focused on solving it, personally.

Yes, but think about the poor shareholders.

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

#97

Post by djmips »

btilly wrote: post #51
jandrewrogers wrote: post #47

Earlier quoted context omitted.

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.

Can you back that up with some references? Very curious, I've never heard any claims that Victoria will end up under water in a big Cascadia earthquake.

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

#98

Post by interloxia »

Retric wrote: post #72
shostack wrote: post #53

Earlier quoted context omitted.

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

Anchorage was 78 miles from the earthquake and still saw mass building collapses. The death toll was low due to the low population in the area. 128,026 in 1970 presumably less in 1964.

About 290,000 in 2022.

https://www.census.gov/quickfacts/fact/table/anchoragemunici...

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

#100

Post by hackernewds »

cc101 wrote: post #34

I can't seem to load this article, but I would like to offer this: I have long thought that the major effect of natural disasters is not the disaster itself, but the social unrest cause by the government not being able to cope. A super quake would be bad enough, but social unrest would make it much worse.

particularly in SF social unrest is viable
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