gdp's Comments

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Thu, 16 Jul 2015 15:29:50 +0000

Well, it could be sort of reassuring but mostly just realistic, I think. I'm sorry these things make you panic! My message is mostly along the lines of "these things will happen and we can't control the planet or hide from them, but we can be reasonably well prepared and try to make informed choices." Which applies to climate change, too: it's already underway and we are well past the point of no return, so now we need to adapt. Happily, we're a very adaptable species.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Thu, 16 Jul 2015 15:25:04 +0000

I'm university faculty.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Thu, 16 Jul 2015 00:01:06 +0000

Oh geez, yeah, geologists can be really bad about color blindness and color schemes for maps. Sorry, on behalf of my colleagues!

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 23:55:01 +0000

Yes, many factors are involved, and not all of them are well constrained. A major subduction earthquake (I don't know what definition of "major" is being used for this stat, but it's usually something like M7.0 or greater) has a 1 in 300 (0.33%) chance of happening in any given year in Cascadia. That could easily be a much smaller event than the worst-case scenario in the New Yorker article, of course. And that probability will be the same next year as it is this year: it doesn't increase next year just because doesn't happen this year. It stays 0.33%. Which is a small chance! Because years are very small increments, geologically speaking! But that also means it's ~100% likely to happen some time in the next ~300 years.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 23:46:53 +0000

Another useful response by some local experts: http://q13fox.com/2015/07/13/local-experts-respon...

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 23:46:08 +0000

Thanks for adding this. The CDC recommendations are going to be good general info. Local and state documents will vary a lot from place to place, so it's more local information.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 23:42:06 +0000

It's easy to forget the distances involved! The subduction zone fault surfaces are either very deep (which is less dangerous for us living on the surface), or shallower but offshore. The volcanoes are more or less surficial (magma chambers usually pool a few to a few tens of km down, and the eruption vents are of course right at the surface) and located inland along the volcanic front. And the melting that produces the magma that rises and makes volcanoes at the surface is occurring very, very deep underground. It takes place in the mantle over the subducting slab, not in the crust. It's happening because of the tectonic setting (dehydration of the subducting plate adds water to the mantle wedge and initiates melting of mantle rocks), and earthquakes are also being caused by the tectonic setting (the upper surface of the subduction slab scraping against the overriding plate), but the earthquakes and volcanoes aren't related otherwise.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 23:34:29 +0000

Rainier is mostly a hazard if you live along one of the lahar-prone valleys, or within a few km of the summit: http://volcanoes.usgs.gov/volcanoes/mount_rainier... Otherwise the main regional hazard from Cascade volcanoes is ashfall, which is something to be prepared for but typically not crippling.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:34:49 +0000

Yes! The radio nerds will save us all in the apocalypse. This is actually why a lot of emergency responder centers use air sirens to notify emergency personnel to report in, at least in communities where they don't have regular tornado siren use/drills (since the use of multiple sirens would be confusing). If cell towers go down and power goes out, they can still use that siren.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:31:12 +0000

Well, for periodic events like earthquakes, short time scales matter a lot! The bigger issue is the one the New Yorker touches on about recurrence intervals being average time intervals, not a ticking clock. Nothing is "overdue" here -- that's not how it works. There is just a certain probability that an earthquake of a specific magnitude will happen in a certain time window on this specific fault. We can't be any more specific than that.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:28:12 +0000

There could still be barrier islands! They just won't be in those places anymore. They'll move inland as the coastline retreats.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:27:09 +0000

Yeah, the other lesson in this is that nothing we make is permanent. Which is true, of course, but not easy. Look at how much effort and money was put into rebuilding parts of New Orleans after Katrina -- despite the fact that none of the levees that failed were the really scary ones (the ones on the Mississippi), and the delta location is intrinsically unstable in the long run. No one wants to abandon a vibrant, culturally and historically important city where millions of people live. No one is going to want to abandon Seattle or Portland wholesale, either. There just isn't an easy solution to these situations, except to prepare as best we can and try to correct old mistakes with any future development.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:20:52 +0000

This is the place that I most hoped the comments would go.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:16:21 +0000

Ha! But it's a useful analogy for familiarity, I guess.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:15:54 +0000

Yeah, that's the combination of the normalcy bias and then the affect heuristic thing with the emotional response. We are all prone to those reactions! Fwiw, most flat areas are going to be floodplains (some might be ancient lakes, but most are river floodplains). The question is how close to the river it is -- is it the 5-year flood floodplain (probably a bad choice), or is it an ancient incised terrace 500 feet above the river (probably cool)?

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:14:00 +0000

I think that the modelers actually do try to do these things, to the extent possible! There was a Cascadia tsunami report that was put together pretty recently -- I'm not an expert on that topic specifically, but I know it was worked on and I'd be surprised if they didn't address the subsidence issue, at least as well as anyone can with current technology. The effect of rising sea level is also important for tsunami modeling and forecasting, but those are longer-term changes: next year's impact would be about the same as this year's.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:10:43 +0000

Hard to say, but probably not a lot. Severe shaking could make some changes in a geothermal plumbing system, so fumaroles or geysers might change geometry and start up or stop, but most of the magma is kilometers underground. If it's already overpressurized and just temporarily prevented from erupting by a rock or detritis plug in the conduit, and that plug is shifted or broken up by shaking, maybe that would trigger an eruption? But those are pretty particular circumstances, and if that's the case I wouldn't be surprised if that thing was probably going to erupt soon anyway. Volcanic eruptions, and magma and gas movement in the subsurface, also cause earthquakes recorded by seismometers (and surface explosions, which are also picked up by seismometers), but they are local and have a different seismic signature from fault motion in a normal earthquake. Volcanic seismicity is quite different.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 21:02:43 +0000

Doorways were thought to be more stable than the rest of a house, but it mostly isn't true (or true enough to matter).

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 18:42:05 +0000

Yes, that is why I added them -- practical knowledge that for most people is very out of date. For lightning storms, it's been recognized that the electrical discharge of a ground strike can travel at least 50 feet out from the strike and affect people through the ground. So you do want to minimize your height so you don't attract a direct strike to your head, but you also don't want to couple your heart to the ground and risk zapping it from 50 feet away. Squatting to lower your height, while creating a short-circuit through your legs (that doesn't go through your heart) might increase survival rates if there is a nearby strike. Or that is the thinking.

The Toast : You Live On Earth: A PSA About Deathquakenami From a Scientist

Wed, 15 Jul 2015 18:39:31 +0000

I don't think this is something an expert in the science would know about, but I expect that in an apocalyptic scenario, there will be poop everywhere. It just isn't sexy to put that in fiction books and movies.