I'm not a science person...please explain that, "beginning of rupture" thanks
Earthquakes aren't a point. They happen along a "plane"...a surface between fault faces.
An epicenter just shows where a rupture BEGINS...it moves along the fault like a zipper.
The epicenter of the December quake was at the south end of the rupture zone..the area where the fault moved....which was over 600 miles long.
The epicenter of this quake was actually south of the December rupture zone; if the rupture started there and moved SOUTH, this isn't really an "Aftershock" of the December quake, but a new quake (likely stress-triggered by the Dec. quake though.)
I'm looking for a good graphic of the rupture zones of 2004, 1861, and 1833..(all big subduction quakes off of Sumatra.)
You misspelled "rature". ;^)