West Coast apocalypse: How “earthquake storms” could devastate California | Hacker News Reader

West Coast apocalypse: How “earthquake storms” could devastate California

salon.com

23 pointsvasusen11 comments

Open articleView on HN

For anyone more interested in this, here are some resources:

Unified California Earthquake Rupture Forecast (UCERF):

http://www.scec.org/ucerf2/

The seminal paper on Coulomb stress change work, by GCP King, Ross Stein, and Jian Lin, with particular focus on SoCal:

http://profile.usgs.gov/myscience/upload_folder/ci2010Jul081...

The classic paper by Ross Stein and friends on the stress evolution of the N. Anatolian Fault:

http://www.ipgp.fr/~armijo/paraseminario/Stein-97.pdf

A short video on coseismic stress change on the North Anatolian Fault:

http://www.youtube.com/watch?v=qAmcVZbnAKc

(Note that the viscoelastic properties of the lower crust and upper mantle lead to a time dependence not shown in these models, which are fully elastic calculations).

"Elsewhere in northern California, a major earthquake along the subduction zone between Cape Mendocino and Vancouver Island—a region known to geologists and seismologists as Cascadia and which the Working Group gave a 10% chance of rupturing in the next 30 years—will almost certainly be followed within decades, perhaps even within hours, by a major earthquake along the northern segment of the San Andreas."

Notable that Sunday evening there was a 6.9 quake in that region which was the California's largest in the past 7 years. I believe a deformation (not a rupture) - but it was just south of Cascadia near where it meets with the San Andreas fault close to the Mendocino triple junction. [1]

[1] http://www.decodedscience.com/m6-9-california-earthquake-lar...

Actually, all earthquakes are ruptures in the sense that they represent slip (displacement) on a surface. Oftentimes, though, geologists and geophysicists will refer to ruptures as the surface break of an earthquake (where the slip on a fault reaches the earth's surface), so some context is required to distinguish between the two.

The recent M 6.8-6.9 event occurred offshore, so it's not entirely clear whether it broke the surface. Most earthquakes below M 6 don't, and most M7 do (if they occur in the crust).

The focal mechanism of the earthquake [1] (see how to interpret them at [2]), which shows (among other things) the pattern of stress change during faulting, does (from my visual inspection) indicate that the Coulomb stress change on the subduction zone north of Mendocino. I'm not sure what the implications are for the northern San Andreas, which may not be optimally oriented to receive additional shear stress from this event, but I think the earthquake might have released some of the normal stress that keeps the fault from slipping there.

[1]: http://earthquake.usgs.gov/earthquakes/eventpage/nc72182046#...

[2]: http://earthquake.usgs.gov/learn/topics/beachball.php

But this isn't the only natural disaster California should be concerned about...

http://en.wikipedia.org/wiki/Great_Flood_of_1862

It's funny just how bad Upworthy is has really pointed out to me how bad Salon is.

They more rely on link bait titles than well written, thought out stories with substance.

I's quite hard to work out if this article has any credibility it jumps around so much.

I'm a postdoc in fault mechanics and earthquake physics. I can say that while the narrative does jump around a bit, the geologic content is fairly solid; coseismic stress changes on faults really do cause substantial changes to the stress state on faults around them, and this can lead to earthquake clusters or sequences (please don't say 'storms').

This is especially clear for strike slip faults (San Andreas, N. Anatolian Fault, Xianshiuhe Fault, etc.), for a couple of reasons:

1) Because the displacement is in the direction of neighboring fault segments that are capable of earthquakes, the stress changes on those neighboring segments are large. On subduction zones and mid-ocean ridges (the other major plate boundary types), the major stress changes are deeper in the earth, where it is hotter and faults deform through ductile shear instead of brittle, seismic slip, so earthquakes don't really occur there.

2): Major, rapidly slipping strike-slip faults are more likely to be found on land than other types of rapidly-slipping faults, so we have a much better record of this process occurring on them. It's a lot harder to find pre-historical/geologic records of earthquakes that occurred under the sea. Tsunami deposits are good, and in the past 10 years study has ramped up looking for them.

Now, I have no idea whether such a sequence wiped out classical Hellenic civilization. I believe (but can't check right now as dinner is ready...) that I have read a paper on a major eruption at Santorini devastating Minoan society.

From the lips of the great prophet Maynard James Keenan: https://www.youtube.com/watch?v=uCEeAn6_QJo

"See you down in Arizona Bay."

...who was referencing the work of the similarly titled Bill Hicks: http://en.wikipedia.org/wiki/Arizona_Bay

Nice, I didn't realize that. I knew that whole album was full of Bill Hicks references, but I didn't know that that was one of them.

That article screams out for some fault maps. And pictures of scarps.

Actually it would work well in the NY Times 'flowing image/text/video' style. But other than that it doesn't really say anything that anyone in doesn't already know. Releasing energy in one part of a fault moves the next point further along the fault.

Reply on news.ycombinator.com