Cathryn.....The distance between epicenters is probably something like 160 km (100 miles), but the distance between ruptures is probably zero...or the ruptures might have even overlapped a little. Epicenters are just where the quake initiated...they then propagate out and break huge areas of fault.

I agree with John that this should not be considered an aftershock, but it was triggered by the 9.3 Dec 26 quake (you could call it a far field aftershock if you want).

OK...why no large tsunami? I heard an interesting idea, but I consider it bad practice to post other's ideas without their permission. Let's discuss ideas here....that is what is interesting...
Chris