Correction...I zoomed into the world quake map and the aftershocks do seem to define a zone over 300 km long (with no large aftershocks in the middle). So, nevermind my saying it is more like 200 km. As for "new gouge under water", I don't know what Glen meant by that. Sea floor mapping and exploration showed some seafloor rupture for Sumatra. You don't have to actually break the sea floor to move it and cause a tsunami. Mike...yes, you are correct about aftershocks....I think those seismologists (who will remain nameless) had trouble at first with a 1400 km rupture...there had never been one that long before...at least not recorded. I think the seismologists thought the northern one were triggered...not part of a continuous rupture.
Chris