There’s an interesting news story in Nature* about a distributed computing project with a seismological twist. The proposed aim of the Quake-Catcher project is to hack and collate data from laptop accelerometers – designed to protect the hard drive when your precious portable is about to meet the pavement – to detect and track the propagation of earthquakes

When a computer signed up to the program senses shaking, it calculates the intensity and pings the information back to the servers at Stanford in less than a second. If enough computers detect ground shaking in the same area, the system could send out a warning to users who haven’t felt it yet that an earthquake is on its way, [Jesse Lawrence, one of the seismologists developing the system] says.

If it works, it will be the cheapest seismic network on the planet and could operate in any country. It wouldn’t be as sensitive as traditional networks of seismometers, but Lawrence says that’s not the point. “If you have only two sensors in an area, you have to have a perfect system. If you have 15 sensors in a system it [can] be less perfect. One hundred, one thousand, ten thousand — your need for the system to be perfect becomes much smaller,” he says. “That’s really our approach — just to have massive numbers.”

I’ve mockingly questioned the actual use of getting a few seconds warning before (and some people rightly pointed out in the comments to that post that even those seconds are potentially very valuable), but I’d imagine the real value of such data will be in tracking how seismic waves actually propagate through particular areas – the effects of both sub-surface structure and topography are an important control on the shaking intensity in any particular place, and are quite difficult to model. But this sort of system is not without it’s own computational challenges, such as producing software that will discriminate earthquakes from knocked desks, slamming doors and passing lorries.
Although I can’t find reference to it on the Quake-Catcher website (their pdf brochure seems to be MIA), the Nature article also seems to refer to a distributed computing application in the more traditional, SETI@home sense:

Little is known about how seismic waves travel and refract deep in Earth’s crust, and modelling this movement accurately takes enormous computing power, which can be generated by combining many different users on the network.

This is possibly referring to producing velocity models of the earths interior by processing teleseismic arrivals (earthquake waves from the other side of the planet that have travelled through the Earth’s interior, as opposed to more local ruptures) from official seismometer networks; I wouldn’t have thought that your lap-top sensor could pick them up such faint tremors from background, although it would be pretty cool if they did. I wonder if it would be practical to cheaply build an instrument that could?
*(I also see that Julian has already blogged about this, knows one of the people involved, and may even get to help beta test…)