The lithosphere of the earth is broken up into what are called tllectonic plates. Underneath the Bay of Bengal, which is part of the great Indo-Australian Plate and is slowly moving north east. This plate meets the Burma Microplate at the Sunda Trench. The Nicobar Islands and the Andaman Islands are part of the Burma Microplate. The India Plate subducts beneath the Burma Plate at the Sunda Trench or Java Trench. Here, the pressure of the two plates on each other increase pressure and temperature resulting in the formation of volcanoes such as the volcanoes in Myanmar, and a volcanic arc called the Sunda Arc. The Sumatra-Andaman earthquake and Asian tsunami was a result of the pressure at this zone causing a submarine earthquake which then resulted in a destructive tsunami.