To be fair, the quake that just hit Tokyo was incredibly deep and lasted a very long time. While as a rule of thumb, a strong quake is followed by only weak aftershocks, in recent history a few strong quakes have actually triggered much stronger quakes sometimes hours later.
@ShinyBat I was just discussing with my soon-to-be-ex-wife on the phone what we do if it this was a foreshock of the big one. I've already got my safe places identified.