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« Briefly, Libya (Cyrus) | Main | 3 QD Arts and Literature Prize winners announced. »

March 20, 2011


Via me via a buddy of mine, that is. Which one was "natural"? Which "man-made"? I know, it's sophistry to ask. It's almost perversely Derridean. But when I ran a casual search for information about tectonic plates near Japan, the leading results included early stories, from 2005 and 2009, predicting a high likelihood of a major quake in the area and the devastating results that would ensue.

Thought provoking.

Well Dean, I hope the "casual search" and the scary e-mails I was writing to you about San Francisco, didn't freak you out too much :-) But seriously, Japan I think, sits on four major fault lines and SF on just one. The plate that moved this time to cause the 2011 disaster in Japan is the same one that extends to the San Andreas fault. I will repeat here why that is significant for your part of the world. This time I will try to get the geographical directions correct too.

I think the fault in the latest disaster area in Japan (Japan sits on several) is part of the same tectonic plate that spans a vast area on the Pacific floor. Think about it. Chile (the southeast corner of the plate) had a major earthquake last year. New Zealand (the southwestern edge) had a significant quake last month. Now northern Japan (the northwest corner). That leaves the northeast part of the plate where the fault line is in S.F. When tectonic plates vibrate, it is like a sound wave traveling through a metal object - all the parts will move, eventually. I am just wondering. Don't mean to scare you.

There are several bits of misinformation here. San Francisco sits on at least two major (depending on how we define "major") fault lines. While the San Andreas is the more famous fault line, as East Bay denizens, of greater concern to Dean and me is the Hayward fault, which runs through the middle of Berkeley's stadium and through a park in which I jog about two miles from my home. We don't need to fall prey to the availability statistic to be concerned. It's historically produced major quakes every 140 years, and last produced a major quake in 1868.

I think you mean plates, not fualts. SF sits astride only two plates (as opposed to Japan), though two additional remnant plates (the Juan de Fuca and Cocos plates) affect the northern and southern reaches of California. I'm not sufficiently knowleadgeable about geology to know how a quake on their borders could affect SF (e.g. tsunami patterns). Chile does not share any plates with SF. It sits on the border of the Nazca and South American plates. The Pacific plate is further west and north. There have also been major quakes in Haiti, several in China, Pakistan, etc. in recent years. I expect that what's changed most is the degree of reporting.

To be concerned about earthquakes in the Bay Area is to be breathing (as my response suggests, I spend a fair amount of time thinking about this), but like being concerned about hurricanes in the Carribean (or NYC-- where they aren't, but really should be or bombs in any number of places in our sad world (back to the theme of this post), there's only so much waking energy that one can commit to it.

That would be availability heuristic, not statistic. We should attend to the availability of statistics!

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