Don...interesting links. Do the math on the 1861 and 1833 rupture zone...how many meters of slip has accumulated? And, what do you think the average slip was on those earthquakes? I'd say it was pretty ripe (they call it 10 months pregnant), or it could wait another 100 years. Kind of like the San Andreas along the 1857 rupture...except the plate loading rate beneath Sumatra is almost twice as high....
Chris