Andaman Sea
The Andaman Sea is a body of water to the southeast of the Bay of Bengal, south of Myanmar,
west of Thailand and east of the Andaman Islands; it is part of the Indian Ocean. It is roughly
1200 kilometres long (north-south) and 650 kilometres wide (east-west), with an area of
797,700 km². Its average depth is 870 meters, and the maximum depth is 3,777 meters. At its
southeastern reaches, the Andaman Sea narrows to form the Straits of Malacca, which
separate the Malay Peninsula from the island of Sumatra.

Ocean floor tectonics
The Andaman Sea, showing tectonic plate boundariesRunning in a rough north-south line on
the seabed of the Andaman Sea is the boundary between two tectonic plates, the Burma plate
and the Sunda Plate. These plates (or microplates) are believed to have formerly been
part of the larger Eurasian Plate, but were formed when transform fault activity intensified as
the Indian Plate began its substantive collision with the Eurasian continent.

As a result, a seafloor spreading centre was created, which began to form the marginal basin
which would become the Andaman Sea, the current stages of which commenced approximately
3-4 million years ago (Ma).

Volcanic activity
Within the sea to the east of the main Great Andaman island group is Barren Island, an active volcano (the only presently active volcano associated with the Indian subcontinent). Its volcanic
activity is due to the ongoing subduction of the India Plate beneath the Andaman island arc,
which forces magma to rise in this location of the Burma Plate. Thevolcanic island of
Narcondam which lies further to the north was also formed by this process; however it has not
recently been active.