[HN Gopher] Multifault earthquake threat for Seattle region reve...
___________________________________________________________________
Multifault earthquake threat for Seattle region revealed by mass
tree mortality
Author : bookofjoe
Score : 216 points
Date : 2023-10-11 01:20 UTC (14 hours ago)
(HTM) web link (www.science.org)
(TXT) w3m dump (www.science.org)
| vidanay wrote:
| Bizarre...I just watched this video this evening.
|
| "Great Earthquakes of the Pacific Northwest"
|
| https://www.youtube.com/watch?v=UJ7Qc3bsxjI
| swatcoder wrote:
| 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 wrote:
| Also there was a small earthquake in the region 2 days ago
| that probably has some people jumpy.
| vidanay wrote:
| 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).
| codetrotter wrote:
| > the topic is "trending"
|
| In which case they might suggest it to you as well, even if
| your personal interests are not closely related to whatever
| happens to be trending?
| vidanay wrote:
| It wasn't suggested to me. I am working my way through
| his lectures and I explicitly went to the channel and
| selected the video.
| pests wrote:
| The next logical question is what set you off to work
| your way through his lectures? Was whatever caused that,
| inspired by this?
|
| I don't think it matters or anything but it is an
| interesting question into virality and where ideas come
| from.
| vidanay wrote:
| Well, that's a long a twisty route...
|
| I was originally watching videos from a guy who goes
| hiking further north in BC. From there, I searched for
| similar videos in WA. From there I saw a couple of videos
| about the modern history (1800's to today) and settlement
| of Seattle and the sound. From there I saw one of Nick
| Z's geology videos which I really liked and have been
| watching them since.
| pests wrote:
| Thanks for the Nick Z rec. Start the video linked
| upthread and already loving it. I recently went on a
| earth formation / geology binge on YT over the last few
| weeks and this is right up my interests.
| codetrotter wrote:
| My bad. I misunderstood what you meant.
| gpspake wrote:
| 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 wrote:
| Nick Zentner has a lot more content on YouTube too (and it's
| all very lovely!), see https://www.youtube.com/@GeologyNick
| vidanay wrote:
| Yes, I've watched 10-15 of them so far.
| cossatot wrote:
| 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
| 23B1 wrote:
| 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.
| cossatot wrote:
| 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...
| 23B1 wrote:
| Fascinating. Thank you.
| [deleted]
| adrianpike wrote:
| 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!
| cossatot wrote:
| 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 wrote:
| 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?
| cossatot wrote:
| 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?
| blincoln wrote:
| 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?
| dmitrysergeyev wrote:
| 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
| [deleted]
| doublerebel wrote:
| 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-...
| DoreenMichele wrote:
| 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.
| mnky9800n wrote:
| 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.
| TheOtherHobbes wrote:
| It's more the other way around. A large earthquake is often
| followed by a swarm of aftershocks, some of which can cause
| significant damage.
|
| The media failed to report that the recent quake in Morocco
| was followed by tens of smaller quakes over the next few
| weeks, all in a small-ish area that had been quake-free.
| (In recent memory, at least.)
| sparrowInHand wrote:
| A fault is a series of hooks, nooking into the oppossing
| plate. One of them giving way, in a small event, gives off
| its energy partially to the surroundings (the quake) - the
| rest- stays as additional pressure on another
| rockformation.
|
| There is a lot of research on people not taking possible
| disasters serious:
| https://en.wikipedia.org/wiki/Normalcy_bias
|
| Its understandable, but in the end also just noise for
| those who do and want to discuss mitigiation strategies or
| statistics. The urge to conjur up security by repeating
| doubt mighte be huge, but like all prayer, should be kept
| to oneself.
| abnercoimbre wrote:
| Definitely felt it for a couple seconds lying still. If you
| were driving or moving about you might've missed it.
| nvy wrote:
| Felt it up here in Victoria, too.
| JALTU wrote:
| Aftershock of Taylor Swift concert?
| kogok89 wrote:
| Didn't feel a thing (2) in North Seattle.
| AISnakeOil wrote:
| Didn't feel a thing.
| psunavy03 wrote:
| Didn't feel a thing.
| cc101 wrote:
| 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.
| e40 wrote:
| 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.
| hackernewds wrote:
| particularly in SF social unrest is viable
| imbusy111 wrote:
| 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
| jandrewrogers wrote:
| 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.
| btilly wrote:
| 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.
| djmips wrote:
| 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.
| interloxia wrote:
| An Ask an Earth-Scientist answer by Dr. Gerard Fryerm
| suggests a few meters is possible.
|
| >"Will part of Vancouver Island "break off and sink," or
| "split in two at Alberni Inlet?" No. In a big earthquake
| the seafloor offshore from Vancouver Island will be
| uplifted and the area along the coast will sink, but at
| worst that sinking will only be a few meters. If you live
| very close to the beach and close to sea level then there
| is a possibility that your house will be flooded, but no
| big piece of the island is going to break off and
| disappear. It is possible that there will be submarine
| landslides along the steepest slopes offshore, but each
| of those is likely only be small in extent.
|
| http://www.soest.hawaii.edu/GG/ASK/vancouver.html
| btilly wrote:
| It doesn't take a lot of meters to pose a big problem for
| Victoria, BC. Look at a topographical map: https://en-
| ca.topographic-map.com/map-1926m2/Victoria/?cente...
|
| That said, https://www.esquimalt.ca/sites/default/files/g
| reater_victori... is built on more up to date information
| than I had. And suggests that subsidence + tsunami is
| only 4 meters. Which doesn't pose a serious threat. (If
| they are wrong and get a 10 meter combination, of course,
| that would be a far, far worse story.)
| seabrookmx wrote:
| It's not like the island will just drop into the earth.
|
| Unless you were referring the tsunami risk, which is my big
| fear as a fellow Victorian.
| btilly wrote:
| The island does subside in these earthquakes.
|
| Reading up now, it looks like it is 1-2 meters, mostly on
| the west coast of the island. But my memory of the early
| research when I still lived there in the early 1990s was
| that it was about a 3 meter drop. Between how low much of
| Victoria is, widespread poorly build older houses, and
| lots of housing built on unstable landfill in places like
| James Bay, my belief was that it was going to be pretty
| devastating to a lot of parts that I knew.
|
| However recent articles like
| https://www.mdpi.com/2624-795X/4/3/13 suggest a much
| milder risk than I had thought.
| lightedman wrote:
| "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.
| 01100011 wrote:
| As I understand it, the entire region is on a flat(well,
| tilted), planar fault because of the way the crust
| subducts. So you can have earthquakes anywhere in the
| western PNW from that.
|
| But remember, the bay area is also home to many, many
| faults, and we don't even know the locations of them all.
| For instance, the next big bay area quake is likely to come
| from the Hayward Fault in the E. Bay.
| jandrewrogers wrote:
| The Seattle fault is a significantly bigger threat to
| Seattle than the Cascadia Subduction Zone and it doesn't
| get nearly as much attention. Parts of the city's
| shorelines could subside up to 10-20 feet, and the tsunamis
| are substantial.
| ksenzee wrote:
| 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.
| [deleted]
| DoreenMichele wrote:
| I wish we were less focused on moving to where we can survive
| this mess and more focused on solving it, personally.
| fransje26 wrote:
| Yes, but think about the poor shareholders.
| oceanplexian wrote:
| 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.
| ghaff wrote:
| You do get flooding and at least residual hurricanes in New
| England. e.g. [1] Depends where your house is of course.
| Some properties are probably pretty well-situated; others
| much less so.
|
| Just about a month ago the city next door to me in MA got a
| freak foot of rain which caused some serious flooding. I
| had to pump water out of my basement for the first time in
| years.
|
| Very few places are immune to at least local natural
| disasters of various types and some of those, like the
| Vegas area have their own long-term issues.
|
| [1] https://www.weather.gov/media/btv/events/1927Flood.pdf
| Axsuul wrote:
| And SF isn't?
| notyourwork wrote:
| No, it isn't.
| mvdtnz wrote:
| I'm no expert on the region but aren't people in California
| forever whining about heat waves and water shortages?
| rconti wrote:
| 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.
| ti30 wrote:
| Longtime Bay Area resident here - I haven't looked at the
| data, but it seems like this area seems to be getting
| colder over the past ten years. If so, it's an
| illustration that we're facing not global warming but
| climate change.
| dheera wrote:
| No, you're looking at just a few years of data on a
| certain region.
|
| When the global average temperature rises some places
| will get cooler from time to time, there are multiple
| underdamped systems at play.
| lazide wrote:
| Well, most things really.
| akkartik wrote:
| California != SF.
| iancmceachern wrote:
| 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.
| DoreenMichele wrote:
| Fresno County has a history of actually increasing its
| groundwater levels intentionally at times. Anyone
| interested in water issues could stand to take a look at
| what they do.
| callalex wrote:
| 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.
| iancmceachern wrote:
| They'd need to change some pretty old laws...
|
| https://www.archives.gov/legislative/features/hetch-
| hetchy/h....
| elliotec wrote:
| Do you have a source for this? What is "best" in this
| context?
| adrianpike wrote:
| Freshwater availability is a big factor that swings in the
| PNW's favor.
| jandrewrogers wrote:
| 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.
| [deleted]
| meowkit wrote:
| 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 normalized thing in
| population centers as basic resources and commodities
| become more expensive. Seattle has a large military
| presence.
|
| Seattle is positioned geographical well for these things.
| Being farther north alone is a huge benefit. The mountains
| of the west due to their proximity to the Pacific enable
| much more temperate climates than other port cities.
| [deleted]
| elliotec wrote:
| 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.
| 23B1 wrote:
| I doubt it. It's an exercise in predicting the future,
| with so many variables, over such a long timeline, that
| any model will just unwind.
| dataflow wrote:
| > 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 wrote:
| 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?
| ksenzee wrote:
| It won't be _that_ big. They'll feel it as far as Idaho
| maybe.
| finite_depth wrote:
| No, but you would feel it well inland throughout the
| Mountain West. See this simulated USGS map for a 9.0 quake:
| https://upload.wikimedia.org/wikipedia/commons/8/80/9.0_Cas
| c... - for scale, the light blues are about the edge of
| where you'd clearly go "oh, yep, that's an earthquake",
| although you might notice such a large one at lower ground
| acceleration because the shaking would be quite prolonged
| (~minutes, rather than the ~10-20 seconds of a typical
| minor quake).
| asveikau wrote:
| 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.
| rapind wrote:
| Rainier will erupt first and the mudslide will wipe out all
| those houses built on the last mudslide.
| seanmcdirmid wrote:
| Rainier erupting would devastate slot of small
| communities between it and Tacoma. Like Helen's blowing
| it's glacial too (liquifying into a muddy huge river) but
| worse since the area around is more populated.
| rapind wrote:
| Yes and a lot of these suburbs are built upon the
| mudslides from previous (recent) eruptions (few million
| people). Last I heard it was a 1 in 7 chance in my
| lifetime. It's incredibly stupid and dangerous. Mudslides
| can travel up to 50 mph or more, and it doesn't even need
| to be an eruption that kicks it off.
| dkasper wrote:
| 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.
| carbocation wrote:
| Yes: a 7.8 is thought to be the max in the Bay Area, as far
| as I understand. E.g.,
| https://www.sfchronicle.com/bayarea/article/only-one-bay-
| are...
| zamfi wrote:
| > remember a 9.0 is 10x the intensity of 8.0
|
| 10x the _ground movement amplitude_ -- 32x the total energy
| release, though!
| Stratoscope wrote:
| 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 wrote:
| Those numbers, while sad, are surprisingly low compared to
| other causes of death.
| Retric wrote:
| 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.
| interloxia wrote:
| About 290,000 in 2022.
|
| https://www.census.gov/quickfacts/fact/table/anchoragemun
| ici...
| seanmcdirmid wrote:
| 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.
| ianburrell wrote:
| 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.
| diogenes4 wrote:
| 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.
| adrianpike wrote:
| 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.
| rnk wrote:
| Good thing I'm 10 miles east from that road of doom, I'm
| sure I'll be safe ;-).
| JieJie wrote:
| You gotta worry about lahars. :)
| karaterobot wrote:
| I'm 10 blocks east, should be fine too. Even if the
| earthquake somehow gets a couple blocks past I-5 (can't
| see how that could happen) I'd still have 7-8 blocks as a
| safety cushion.
| diogenes4 wrote:
| > 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.
| adrianpike wrote:
| I'd love to find any actual FEMA publications that back
| up some of the numbers and claims - so far to the best I
| can tell is it's mostly from interviews with the regional
| director, which, while valuable, isn't quite at the level
| of citation I'd like. If anyone's got a PDF I'd love to
| retract all my critiques though. :)
| ianburrell wrote:
| The news articles exaggerate things either for effect or
| didn't realize quakes diminish with distance. The shaking
| for mag 9 at Portland is similar to mag 7 nearby. One
| difference is that quake will go on for minutes making
| liquefaction worse.
|
| There will be lots of damage in Portland. There are lots of
| unreinforced masonry that will collapse and kill occupants.
| Most of the bridges, big and small won't survive cutting
| off from outside. Infrastructure will be destroyed and
| utilities will be out of months. All of those could be
| upgraded which is why Bay Area would be in better shape.
|
| Also, this is talking about Portland and Seattle. Most of
| the destruction will be on the coast which is closer to the
| fault. The tsunami will cause lots of damage, destroying
| most of the towns and killi;g everyone that doesn't
| evacuate to high ground.
|
| The 2011 Japan quake is the best comparison but
| Portland/Seattle aren't prepared like Tokyo, and there are
| minimal tsunami defenses.
| mhb wrote:
| https://www.newyorker.com/magazine/2015/07/20/the-really-big...
| tony_cannistra wrote:
| 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.
| Exuma wrote:
| 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 wrote:
| Is there a better resource?
| nnf wrote:
| I read this article about once a year, and it terrifies me
| every time.
| isoprophlex wrote:
| _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%0)
| 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 wrote:
| Can we do the reverse process, find solar proton events from
| dendrochronology data?
| MiguelVieira wrote:
| Yes
|
| https://www.reuters.com/science/huge-ancient-solar-storm-
| rev...
| jumploops wrote:
| 500 error on site, alternative link:
| https://pubmed.ncbi.nlm.nih.gov/37756412/
| varenc wrote:
| Same for me, super odd. Seems related to my browser state. It
| works fine in an incognito window.
| [deleted]
| jumploops wrote:
| Strange, works in one Chrome profile but not the other...
| tony_cannistra wrote:
| 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)
| mannykannot wrote:
| 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 wrote:
| 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
| monknomo wrote:
| It's not "access to trees" so much as "access to large, old
| growth trees". The old ones with tight growth rings, large
| widths and long straight trunks are actually kinda rare
| these days. The farmed stuff is not the same, compare the
| growth ring per-inch
| mateo- wrote:
| that 3rd pic could be a black metal album cover
| johnfonesca wrote:
| Dimmu Borgir presents their new album "Undying Chainsaw"...
| ithkuil wrote:
| That's what Alice in chains saw
| 83 wrote:
| "Deep Cuts"
| p1mrx wrote:
| https://i.imgur.com/6UFnqxT.png
| hackernewds wrote:
| very well done
| martin_a wrote:
| I liked their first album better, but okay.
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