Seismic science questions We just (20mn ago) suffered from another strong aftershock (of the initial March 11th earthquake) in Japan.
I have some questions related to seismic science. 


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*Why is there so much time between the initial quake and the following strong aftershocks (initial was March 11, the stronger aftershock happened 20mn ago, April 7)?

*Why does it seem that progress in seismic science (and quakes predictions) is so poor? It seems people have only raw probabilities, based on historical data.

*Would anybody have any graphical / imagery data of the physical fault move on March 11?
Thank you.
 A: 
Why does it seem that progress in seismic science (and quakes predictions) is so poor? It seems people have only raw probabilities, based on historical data.

It's because the actual earthquake depends on tiny initial events.
Imagine standing on a glass so it breaks. We can calculate how much force it takes for a glass to break. But it would be very hard to predict in advance at which microscopic atomic scale flaw in the material the crack will start and at exactly what nano-second.
An earthquake is just the same on a larger scale.
A: I also live in an earthquake prone region,in Greece, and we got a 6.3 a week or so ago, fortunately in the middle of the sea between Crete and Carpathos.
We got two stong ones in  Athens during my life time: one in 1981 and one in 1990, from different fault lines, though all of them finally are due to the fact that the African plate is pushing against the European one. At the time of the shocks all physicists in my region read up on seismology. It is not an advanced science. Some tried to predict aftershocks with dubious results : large error for epicenter, large error on time, etc. 
It is known that the pressure builds at the fault until it breaks. Then the system settles with "small" after shocks, going on for months. Large after shocks can also happen. Predictions are very uncertain.
This link may help.  
