 The shock was centered from the trench, and about from the south coast of the island.A comparison was made with the earlier 2002 Sumatra earthquake, a M7.5 submarine earthquake of a similar size that also occurred along the Sunda Arc and at a shallow depth, but one that did not result in a tsunami.The large and damaging tsunami that was generated was out of proportion relative to the size of the event, based on its short-period body wave magnitude.