Mariana Islands Volcanic island chain in the w Pacific Ocean, stretching over 800km (500mi) of the Marianas Trench, c.2400km (1500mi) e of the Philippines. The group comprises Guam and the islands of the Northern Marianas: Saipan, Tinian, Rota, Pagan, and 11 smaller islands. Discovered by Ferdinand Magellan in 1521, and named Islands of Thieves, the islands were renamed the Marianas in 1668. The Northern Marianas came under German control in 1898, subsequently passing to Japan. Taken by US forces in 1944, they became part of the US Trust Territory of the Pacific Islands in 1947. In 1978, the Commonwealth of the Northern Mariana Islands formed in association with the USA, and in 1986 the islanders acquired US citizenship. Trusteeship status ended in 1990. Exports include sugar cane, coconuts and coffee. Tourism is important. Area (excluding Guam): 464sq km (179sq mi). Pop. (2002) 78,400.

Marianas Trench The oceanic trench which marks the destructive margin between the Pacific Plates and Philippine Plates. The trench is about 11 km deep, and there is evidence of little or no accretionary wedge. The subduction zone steepens at depth, becoming almost vertical, with hypocentres down to approximately 700 km.