Multifault earthquake threat for Seattle region revealed by mass tree mortality

https://www.science.org/doi/10.1126/sciadv.adh4973

by bookofjoe • 3 years ago

242 142 3 years ago

science.org

jumploops2• 3 years ago

500 error on site, alternative link: https://pubmed.ncbi.nlm.nih.gov/37756412/

jumploops2• 3 years ago

Strange, works in one Chrome profile but not the other...

varenc• 3 years ago

Same for me, super odd. Seems related to my browser state. It works fine in an incognito window.

vidanay5• 3 years ago

Bizarre...I just watched this video this evening.

"Great Earthquakes of the Pacific Northwest"

https://www.youtube.com/watch?v=UJ7Qc3bsxjI

swatcoder• 3 years ago

On the contrary, that video probably surfaced for you precisely because this study is making the rounds. More people than usual are probably searching for and watching stuff about Seattle seismology.

As it turns out, the algorithm does not work in such mysterious ways.

bawolff• 3 years ago

Also there was a small earthquake in the region 2 days ago that probably has some people jumpy.

vidanay5• 3 years ago

I've been watching a bunch of Nick Zentner's lectures for the last few weeks and I live nowhere near the PNW, so my case I doubt it was algo based. I have no doubt that in general you are right and the topic is "trending" (for whatever that means these days).

gpspake• 3 years ago

One day I got to work early before anyone else was there and I was daydreaming pondering earthquake scenarios and what I would do if one happened (I was on an upper floor).

It wasn't until hours later when I checked the news and heard conversations around the office that I realized I had felt an earthquake and just didn't realize it. It had never even occurred to me

I think living in a city I'm just accustomed to a car driving by in a parking garage and various other rumblings so I never considered that's what it was. Later in retrospect, I recognized that being on the 7th floor of a concrete building, nowhere near a parking garage or construction, that was the only explanation.

The most memorable part of the experience was realizing that my unconscious brain recognized it long before I processed it consciously.

eigenform• 3 years ago

Nick Zentner has a lot more content on YouTube too (and it's all very lovely!), see https://www.youtube.com/@GeologyNick

vidanay5• 3 years ago

Yes, I've watched 10-15 of them so far.

doublerebel• 3 years ago

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-...

nvy• 3 years ago

Felt it up here in Victoria, too.

AISnakeOil• 3 years ago

Didn't feel a thing.

psunavy03• 3 years ago

Didn't feel a thing.

kogok89• 3 years ago

Didn't feel a thing (2) in North Seattle.

JALTU• 3 years ago

Aftershock of Taylor Swift concert?

DoreenMichele7• 3 years ago

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.

mnky9800n2• 3 years ago

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.

abnercoimbre• 3 years ago

Definitely felt it for a couple seconds lying still. If you were driving or moving about you might've missed it.

klardotsh• 3 years ago

Yeah, I'm in Kingston so felt that one plenty. It was a weird one: less rumble, more a sudden jolt that shook the floor. Really weird.

imbusy111• 3 years ago

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

dataflow• 3 years ago

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?

xattt• 3 years ago

I’m wondering how far the big one will be felt. As egocentric as my question is, will I feel it on the East coast?

asveikau• 3 years ago

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.

dkasper• 3 years ago

From what I’ve read the faults in the Bay Area can’t really generate above an 8.0, whereas the cascadia zone can produce much larger events (remember a 9.0 is 10x the intensity of 8.0). It has to do with the size and type of the faults.

ianburrell2• 3 years ago

The Cascadia quake will be about same damage to Seattle and Portland as Bay Area quake. It could be up to magnitude 9 but the fault is 60 mi away from the cities. The big difference is that it will affect the whole area. And that PNW is way behind in infrastructure.

diogenes42• 3 years ago

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.

ksenzee2• 3 years ago

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.

Axsuul• 3 years ago

And SF isn't?

elliotec2• 3 years ago

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

oceanplexian• 3 years ago

People were saying that about Vermont, then last summer they had massive flooding that put cities under several feet of water.

I knew a lot of, frankly over-confident people who moved to New England because the news told them it was good for Climate Change. I think the “experts” know a lot less about Climate Change impacts to weather than they want to admit.

DoreenMichele7• 3 years ago

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

Stratoscope• 3 years ago

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:

https://www.life.com/history/the-great-alaska-earthquake-of-...

https://ready.alaska.gov/_64Quake/History

https://earthquake.usgs.gov/earthquakes/events/alaska1964/

https://en.wikipedia.org/wiki/1964_Alaska_earthquake

From Wikipedia:

As a result of the earthquake, 131 people are believed to have died: Nine died as a result of the earthquake itself and another 122 died from the subsequent tsunamis all over the world. Five died from the tsunami in Oregon, and 12 died from the tsunami in Crescent City, California.

shostack• 3 years ago

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

seanmcdirmid2• 3 years ago

My mom was a schoolgirl in anchorage during the earthquake. We have a picture of my grandma and her trailer being 20 feet down from the rest of the ground. Haven’t digitized it yet.

jandrewrogers3• 3 years ago

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.

btilly3• 3 years ago

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.

lightedman• 3 years ago

"The fault is at least 150 miles from Seattle proper,"

Looking at my geological units map of Washington, Seattle is surrounded by a lot of faults, much like parts of Southern California. Some of those much, MUCH closer than 150 miles, and devastating if they go. I can see one going from Port Angeles, crossing the 101, and going into Port Gamble. It likely continues to run either directly under Seattle or just south of it, in fact that might be the continuation of that reverse thrust fault dead south of Seattle which is shown in the map for the story article. If that one goes, Seattle's not having a good time.

mannykannot4• 3 years ago

Your experience depends quite a bit on where you live and/or work, or, more specifically, what's underneath it. If one has nothing to do with the Millennium Tower, that is probably a plus.

mhb• 3 years ago

https://www.newyorker.com/magazine/2015/07/20/the-really-big...

nnf• 3 years ago

I read this article about once a year, and it terrifies me every time.

tony_cannistra2• 3 years ago

Some friends I know who work in earthquakes maintain that this article caused a measurable increase in the amount of funding available for earthquake research.

Exuma2• 3 years ago

This article actually is loaded with inaccuracies. I once called the local earthquake office where I live, where the local scientists and such work.

They said this article is the bane of their existence because of people calling into their office with false beliefs that have just propagated into fear over time.

I dont even think the sentence got out of my mouth "so about that article I saw...", I was calling to see if my area was in danger of a tsunami, and she gave relieved my fears greatly.

It will be bad, but also there's a lot more nuance to it.

molsongolden• 3 years ago

Is there a better resource?

tony_cannistra2• 3 years ago

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)

mateo-• 3 years ago

that 3rd pic could be a black metal album cover

johnfonesca• 3 years ago

Dimmu Borgir presents their new album "Undying Chainsaw"...

p1mrx• 3 years ago

https://i.imgur.com/6UFnqxT.png

83• 3 years ago

"Deep Cuts"

mannykannot4• 3 years ago

Harvesting timber from trees submerged by the creation of reservoirs is a viable business, I believe, on account of rising prices, particularly for high-quality lumber that is becoming scarce.

kalupa• 3 years ago

I suspect there's still plenty of much, much easier to access trees. The macro-economic effects of the wars, and covid, often causing gasoline prices increases (which is used a lot in forestry) that are still adding pressure to almost all commodity prices, including lumber

Arrath• 3 years ago

It certainly can pay off. My dad was involved in a project removing old logging roads and in doing so they salvaged a lot of old growth timber that had been buried in swampy ground to make corduroy roads, beautiful straight grain, knot free wood. Buried as it was it was very well preserved, and he stockpiled some off to the side in our shed.

Now one piece adorns my parents new house as the lintel board above the fireplace, and its absolutely gorgeous. I think a some chunks were gifted to an acquaintance who builds guitars, and some more were given to a Salish descended carver.

dmitrysergeyev• 3 years ago

There’s a nice government’s map that demonstrates potential impact of the various quake scenarios in Seattle: https://experience.arcgis.com/experience/2acb05d732134331bc0...

An interesting observation is that Cascadia Subduction Zone is potentially less devastating than Seattle Fault despite being capable of a 100x bigger magnitude (9+ vs 7.2) thanks to a longer distance from the city

cc101• 3 years ago

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.

hackernewds2• 3 years ago

particularly in SF social unrest is viable

e40• 3 years ago

After the 89 quake in the Bay Area the people in Oakland came together and were incredibly helpful to each other. The freeway that collapsed was in a pretty bad part of town, yet there was no social unrest, only unity.

cossatot4• 3 years ago

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 through empirical 'scaling relationships'; larger offsets are of course indicative of larger earthquakes. These are simply functions relating a measurable attribute of the earthquake to its magnitude. In the study I did, we combined the measurements of the offsets of a number of paleoearthquakes with estimates of the map length of the fault lines involved and used length-magnitude scaling relations to further refine the final magnitudes. There are some corrections for sampling bias that are included in there and it's all nice and Bayesian if anyone wants to nerd out on the stats.

When we did the study, it was speculated that two of the paleoearthquakes, one on the Seattle Fault and one on another fault on the Olympic Peninsula, could have actually occurred in a single event, but there wasn't much evidence to support this; we consider the magnitude of it on a paragraph at the top of page 1149 but not in the rest of the paper. The recent study (TFA) makes it highly likely that they were part of the same earthquake, but they could be separate earthquakes spaced a few minutes to a few months in time (think of the 7.8 and 7.7 earthquakes in Turkiye this spring, separated by a few hours).

A bit of context about the earthquakes in the Seattle region as well as Cascadia and other areas:

- The earthquakes in the Puget Lowlands and vicinity are relatively infrequent; there are about 15 known earthquakes over the past 17,000 years, and many of them are relatively small (M 6-7). However, they are spatiotemporally clustered[1]: There was a big cluster about 900 AD, and things have been mostly quiescent since then. It can be also shown from the geologic data that at the measurement sites ('paleoseismic trenches'), there haven't been any earthquakes since 17,000 years ago (when the Puget ice sheet retreated) on many of the faults, although the Seattle fault has had a number of earthquakes before.

- The big Cascadia subduction zone events are more frequent (perhaps every 500 years?) and larger, but they may not all be M 9 events, unlike what has been discussed in the famous New Yorker article. That article is based largely on the research of Chris Goldfinger, a scientist at Oregon State University, whose views are credible but on the high side of credible, in the eyes of many other scientists in the region. Many of the earthquakes suggested by the geologic data could be smaller earthquakes (M 7.5-8.5) which won't cause as much ground shaking over such a wide region.

- Earthquakes cause seismic waves at the fault surface, and these attenuate as they travel through the earth towards the surface. The initial magnitude of the waves as the earthquake occurs can be different for subduction zone earthquakes than for shallow earthquakes in the crust, and the attenuation is different for these as well. But importantly, not only are subduction zone earthquakes far off shore, but much of the seismic energy is released deeper in the earth as well, which means more attenuation of ground shaking by the time the waves make it to Seattle.

- A Cascadia earthquake will cause widespread but perhaps moderate damage across the PNW with perhaps, but a strong Seattle fault earthquake will absolutely destroy central Seattle, particularly Pioneer Square and Sodo. The fault comes ashore at Alki Point, for reference. However areas farther away (Edmonds, Tacoma, etc.) will not see nearly as much damage.

- SF and LA both have higher seismic hazard than Seattle[2], considering all earthquake sources, the frequency and magnitudes of earthquakes from the sources, and the seismic ground motions emanating from all of these earthquakes to a site within any of the cities, according to the most recent USGS national seismic hazard model. (See Figure 12 for hazard curves for major US cities).

[0] https://rocksandwater.net/pdfs/styron_sherrod_bssa_puget_eq_...

[1] https://pubs.geoscienceworld.org/gsa/geosphere/article/10/4/...

[2] https://journals.sagepub.com/doi/10.1177/8755293019878199

adrianpike4• 3 years ago

Thanks for jumping in with your experience - every time the New Yorker article makes the rounds, I do a little light digging to try and find some sources the author based it on. Reading through some of Goldfinger's publications will help unlock a bit more, thank you!

cossatot4• 3 years ago

This is the most recent review paper of Cascadian seismicity: https://www.annualreviews.org/doi/abs/10.1146/annurev-earth-.... I would start here instead of Goldfinger's work, as there is a lot of other science to consider.

soultrees• 3 years ago

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?

cossatot4• 3 years ago

Typically the analysis is done by digging trenches across the fault and dating pieces of charcoal found in the sediment with radiocarbon. This study is rare but not unique in using cored trees, or slices of stumps if possible, and dating the event with tree ring dating (dendrochronology), which is vastly superior when it's possible (i.e. when it is demonstrable that an earthquake kills trees). In both cases you want as much as you can get--ideally 5-10 ages at a minimum I think?

23B13• 3 years ago

Thank you for this fascinating comment.

Out of curiosity, do you have any insight as to the Portland, OR area? We always seem to get glossed over in discussions about the PNW and the West Coast in general.

cossatot4• 3 years ago

Portland is probably similarly affected by the subduction zone, but the inland fault system is not as active as in Seattle. Nonetheless, there is a fault that is underneath the Portland Hills that could do some damage to the city.

The seismic risk faced by a city or an individual is really the product of the hazard (formally, the probability of a certain level of ground shaking) and the response of the building stock or other infrastructure. Fortunately, both cities have a large amount of wood-framed housing, which performs quite well in earthquakes (as do modern apartment buildings). However there are a lot of old masonry buildings used for schools, offices, etc. If these aren't properly reinforced, they can be deadly, not only because they are fragile but because they are heavy when they do collapse. But if you live in and work in a modern structure or an old wooden one, you'll probably make it through alright, as long as you have some food and water at home.

The big concern in both cities is actually liquefaction, where some water-saturated soils lose their strength during an earthquake. In both cities, there is some amount of housing stock built on liquefiable soils, but there is a huge amount of commercial and industrial building stock built out on fill dirt on the respective waterfronts (which is where the old masonry buildings are as well). One of the scariests scenarios is the Critical Energy Infrastructure in NW Portland, where massive amounts of oil are in the huge tanks built on fill into the Willamette, liquefying and then spilling into the Willamette/Columbia: https://www.multco.us/sustainability/cei-hub-seismic-risk-an...

blincoln• 3 years ago

In the late 90s, I took a geology course at Seattle Central, and the teacher told us the reason Alki Point has such a nice flat area all along the beach is because that area used to be the tide flats, but during an ancient earthquake, that entire chunk of West Seattle rose something like 10m in less than a minute and retained that elevation from then on. Is that still the current understanding?

jmcqk6• 3 years ago

To what extent do you think about micro-quakes are effecting the subduction system? I've heard that we see the land deforming, building tension from the subduction, but there is also a regular cadence where the land deformation reverses temporarily. When I heard about it (Nick Zentner popular lecture), it was suggested that it might be relieving the stress from subduction more evenly, and not allowing it to build up.

isoprophlex• 3 years ago

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.

pbhjpbhj• 3 years ago

Can we do the reverse process, find solar proton events from dendrochronology data?

MiguelVieira• 3 years ago

Yes

https://www.reuters.com/science/huge-ancient-solar-storm-rev...

Multifault earthquake threat for Seattle region revealed by mass tree mortality

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