|The 8.9 Richter scale earthquake that triggered the Asian tsunami on 26 December 2004 had a lasting effect on this location, part of India's Andaman and Nicobar Islands chain.|
The formerly submerged coral reefs that ring North Sentinel Island are now exposed to the surface, as the entire North Andamans group has experienced tectonic uplift. Circumstances were reversed to the south in the South Andaman and Nicobar Islands, where large land areas were submerged down to between one and four metres in depth.
The international collaborative programme CORDIO (Coral Reef Degradation in the Indian Ocean) estimates that these uplifted North Sentinel Island reefs are unlikely to survive, as either they are positioned too high for high tide to reach them or submerged too shallowly to tolerate the increased intensity of sunlight.
The 72-square-kilometre-area North Sentinel Island is home to the fiercely independent Sentinelese tribe, known to reject any contact with outsiders. The Indian government carried out its 2001 census of the Island from a distance, counting a total population of 21 males and 18 females, although other estimates range higher, to a maximum of 500.