[nmh]

How do you KNOW they are after shocks?

Couldn't it be just a plausible that they are new earthquakes?

Unless you can see them, you really can't distinguish between the two - at least that is what I have been told. Japan and Californian aren't exactly next door neighbors.

[Strategerist]

I was referring to the 5.0 quake off California this morning as an Aftershock.

The 6.1 quake off Japan has nothing to do with the 7.2 or 5.0 quakes off California; just basically normal activity for Japan.