Wednesday, March 3, 2010

climate and earthquakes

Ok, I'm back! And boy, did I miss out on all sorts of geology-related stuff. The biggie, of course, is the earthquake in Chile. It does prove what I said here - that one of the big problems with earthquakes is the structural integrity of the buildings rather than just the shaking itself. Just compare magnitudes and death tolls from Chile and Haiti.

But that's not what had me all fired up about earthquakes earlier this week.

I saw this article about the Chilean earthquake and started reading the comments. I read the first couple pages and was horrified by the number of people blaming global warming for the earthquake.

Seriously? What possible connection is there? Global warming = atmospheric issue. Earthquake = rock issue. Ok, so certain people think "mother nature is angry" because of our various environmental sins, of which global warming is the most popular right now. We can eliminate that as a scientific explanation.

But if you read far enough, several people advance a theory that sounds plausible if you don't know much about earth science. It goes like this: glaciers in the Andes have been receding, thanks to global warming. The removal of all this weight (isostatic rebound) caused the earthquake. Ergo, global warming caused the earthquake.

There's a simple way to refute this. Global warming may have potentially impacted glaciers over the last, say, 20 years. This (wikipedia) lists all of Chile's known earthquakes back to the 1500s. Note that the most recent quake is not even that memorable in comparison, with 4 other earthquakes listed with the same or higher (estimated) magnitudes. Hell, the 1960 Valdivia earthquake in the same area was the largest recorded.

Yes, isostatic rebound can cause earthquakes. But the size of this particular earthquake is totally out of proportion to the pressure release from the melting of some glaciers.


Cannibal Panda said...

At least it isn't as bad as that HAARP conspiracy theory. I came across an article about it by chance and had to laugh at some of the preposterous allegations in regards to HAARP causing the earthquake(s).

I hadn't heard about this one (Global warming). Sometimes I wonder just where they come up with this stuff.

Christoph said...

I agree that it's unlikely in the case of climate change. However, the isostatic rebound after the last glacial caused really big events (not only) in Sweden. Mörner has done a lot of work on this topic, a good example is here:

I know that Mörner's work on climate change well... let's say: under discussion in the community. But his studies on paleoseismicity are quite interesting.