The earthquake originated due to slipping of about 1,200 km of fault line by 15 m along the subduction zone where the India Plate subducts the Burma plate at the Sunda Trench.

The resulting tsunami devastated the shores ranging from the coast of Indonesia to the east coast of Africa, some 8,500 km away from the epicentre.

Bangladesh had very few casualties because the quake-aff ected fault line was in a nearly north-south orientation, the greatest strength of the tsunami waves was in an east-west direction.