A Burma Sea boxed by islands and still vibrating from 2004
The Andaman Sea—once called the Burma Sea—is a northeastern Indian Ocean basin edged by Myanmar and Thailand and screened from Bengal’s open bay by the island chain of Andamans and Nicobars. Fisheries and tourism thrived until the December 2004 quake-tsunami smashed coasts and reefs.
Stretching roughly 92°–100°E and 4°–20°N, this basin lies off Myanmar’s southern shores, Thai western coasts, and Indonesia’s northern approaches, yet stayed poorly explored for ages. The International Hydrographic Organization’s Burma Sea limits run from Sumatra’s Ujung Raja through Nicobar waters to Little Andaman so that narrow channels count with this sea, not the Bay.
Coral islands and busy coastal trade made it a holiday and protein engine; rebuilding after 2004 became a regional project.
Its eastern and northern margins are shallow, since the continental shelf off Myanmar and Thailand reaches more than 200 kilometres out, and silt from the Irrawaddy keeps those waters under 180 metres. The western and central zones drop to 900–3,000 metres, and submarine valleys east of the Andaman–Nicobar Ridge pass 4,000. Together the Irrawaddy and Salween deliver over 600 million tonnes of sediment a year, much of it piling into a mud wedge up to 60 metres thick in the Gulf of Martaban.
A north–south seam between the Burma and Sunda plates runs beneath the seabed, and at least six earthquakes of magnitude 8.4 or more have struck, in 1797, 1833, 1861, 2004, 2005 and 2007. East of Great Andaman stands Barren Island, the only active volcano associated with the Indian subcontinent, which reawakened in 1991 after nearly two quiet centuries. Monsoon winds flip with the seasons, northeasterlies from November to February and stronger southwesterlies from May to September, and rainfall reaches 3,000 millimetres a year.
Source: Andaman Sea
