Mururoa

Mururoa, atoll at the south-eastern extremity of the Tuamotu Archipelago, French Polynesia, in the South Pacific Ocean. The atoll is the summit of a weathered and apparently extinct volcano which has sunk back into the sea. The volcano is a sea mount, or largely submerged island, which rises from deep basalt bedrock in the ocean floor more than 4,000 m (13,100 ft) below sea level. The rim of its crater, which is topped with coral, forms a narrow, irregularly shaped oval ring enclosing a large, shallow lagoon. Mururoa is 30 km (19 mi) long. It became famous as the site of a series of controversial French nuclear tests in 1995 and 1996. The tests were fiercely opposed by other Pacific countries, and caused severe rioting in Papeete, Tahiti, 1,200 km (750 mi) to the north-west, which led to the tests being suspended later in 1996. Nuclear tests have been carried out at Mururoa since 1966. The island was chosen because it is far from centres of population. At first there were atmospheric tests, but these were stopped in 1975 because of severe surface damage to the atoll. Between then and July 1991, 108 underground nuclear explosions were carried out at Mururoa. All the later tests have been carried out in the basaltic core or plug of the volcano, at depths up to 1,200 m (3,940 ft). Severe damage has been caused to the underwater structure of the sea mount, heightening the risk of nuclear pollution of the ocean. The atoll has no permanent population.