 Pre-instrumental events were the large to very large events of 1840, 1867, and 1875, but unlike the northwestern Sumatra segment, no megathrust earthquake has occurred on the Java segment of the Sunda Trench in the last 300 years.The earthquake was the result of thrust faulting at the Sunda Trench.A rupture length of approximately (and an unusually low rupture velocity of per second) resulted in a duration of about 185 seconds (just over three minutes) for the event.