Kilauea

Kilauea, the world's most active volcanic crater, central Hawaii Island, Hawaii. It is located on the south-eastern slope of the great volcanic mountain Mauna Loa, at an elevation of 1,247 m (4,090 ft) above sea level, more than 3,000 m (almost 10,000 ft) below the summit of the mountain. The crater, which forms a great cavity in the side of the mountain, has an area of about 10 sq km (4 sq mi); the walls of the crater are from 60 to 210 m (200 to 700 ft) high.

Except for occasional lava flows across the floor of the crater, volcanic activity in recent times has been restricted to an inner crater called Halemaumau, which measures more than 900 m (3,000 ft) across and has a depth of about 400 m (1,300 ft). Normally, lava streams constantly flow into the floor of the crater from subterranean sources and either cool and harden or accumulate until they drain off into other subterranean passages. During greater volcanic activity, the lava is subject to sudden changes of level, when it may escape from vents on the lower slope towards the sea.

In the early to mid-20th century, major flows occurred in 1920-1921, 1950, 1955, 1959, 1965, and 1969. The current eruption cycle, the longest-running in modern Hawaiian history, began in 1983. The volcano spews about 382,000 cu m (500,000 cu yd) of lava a day and by 1987 had added more than 20 acres of new land to the island. By June 1989, it had destroyed the visitors centre at the Hawaii Volcanoes National Park, and more than 65 houses by 1990. Since 1911 an observatory has been maintained on the brink of the crater.