Alarms That Blows my Mind

So earthquakes are exceedingly common in Japan.  I don't think people outside this area realise just how common they are.  This isn't stupidity, it's simply that we only ever learn (and subsequently talk about) massive earthquakes that destroy everything.

What they have for their mobile phones here is quite interesting - it's an earthquake early warning system.  When a quake is about to hit, a specialised alarm sounds.  I say specialised, because it appears that the manufacturers have all gone with the same signal (although this could be pure coincidence).  One of the things you learn in geography is that earthquakes can be predicted with the same accuracy as carbon dating, that is to say within a hundred million years.  When there hasn't been an earthquake for a century, the next one will be big.  Their way of predicting is also in-line with the way yellowstone authorities have predicted an eruption; the ground is bulging upwards at an alarming rate, and there hasn't been a serious eruption in some time.  It could explode tomorrow, or within the next 10 million years.

Basically, when the warning sounds you have all of ten seconds to get away.  Unless you are next to the epicentre, at which point the alarm sounds simultaneously.  Unfortunately the epicentre is where the most warning is needed, but the least is given.  Such is the limit of technology.  Regardless of the fundamental limitations of such a warning system, it still strikes me as incredible that they have stuff like that available to everyone with a phone.  It's remarkable how well it seems to work.

The upshot is that we had a paltry 4 today.  It barely shook the room, but it was interesting what the staff did with the information they were given with the early warning system (which doesn't give information as to how large the quake will be).  They all just stood there, stock still.  They didn't move, didn't dive under desks, they just stood there.

It also interests me what would have if an earthquake occurred at right angle to the track of a fast moving train.  The really big quakes can move metres, and a train track is less than a metre wide.  Would the train just  continue in a straight line, even if the track wasn't underneath it?