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Tsunami Relief Appeal

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thermidorthelobster:
Fortunately, it's fairly easy to differentiate between explosions and earthquakes using seismographs, because with an explosion the seismic waves spreading from the centre are all compression, whereas with an earthquake you get a cross-pattern with compression on opposite corners, and rarefaction on the other opposite corners.  If that makes sense.  So with something like this, it's pretty easy to tell if it's man-made.

That's not to say that nuclear testing doesn't trigger earthquakes, but the energy released by an earthquake like this one is many orders of magnitude greater than a nuclear explosion, so it's not that likely that a nuclear test would make much difference to the timing of an earthquake.  Small earthquakes have been known from nuclear tests, but nothing on this scale.  Plate boundaries are big old things involving unimaginable amounts of mass and forces.  Also, nuclear powers tend to err on the side of caution and do their testing some way away from plate boundaries, on the whole.

Interestingly, there was an incident in Australia a few years back (1993 I think) which bore all the seismographic hallmarks of a nuclear test, which is a bit odd since Australia weren't doing one.  Strange coincidence (or perhaps conspiracy theory) that the area it happened in was owned by the Aum Shinrikyo cult that subsequently released nerve gas in the Tokyo subway.  As it happens it was probably a meteorite, but I'm not sure if anybody ever found the crater & confirmed it all.

thermidorthelobster:
BBC Online has some fairly stunning images of the devastation from the air:  particularly the second and third.

http://news.bbc.co.uk/2/hi/in_pictures/4142425.stm

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