A tsunami over 30 metres (100 feet) high followed the explosion and apparent caldera collapse, killing about 36,000 people on the adjacent shores of Java and Sumatra.
In major caldera collapses associated with explosive volcanoes (see below Calderas), huge pyroclastic flows may issue from the ring fractures as the caldera block subsides.
Until recently geologists had believed the caldera formed in 1790 during a period of large explosions, and the volcano was quiet in the proceeding centuries.
Fly to Sacramento airport Stay at A park campsite for $12 (redwood.national-park.com/camping.htm), or at the Turtle Rocks Oceanfront Inn, from $180 Grant Roden, naturalist and guide, tour operator Redwood Adventures, Orik, California After a volcanic explosion 7,700 years ago blew the top off Mount Mazama, the collapsed caldera filled with water to become Crater Lake, Oregon's only national park.
In 1790, however, a paroxysmal steam explosion killed part of a Hawaiian army marching near the caldera.
Some caldera basins evolved with gently sloping sides, however, due to the deposition of material from a series of explosions and a gentler collapse of the structure.
This bowl-like basin, 15 miles wide at its widest, is the collapsed dome, or caldera, of a volcano that last erupted about 1.2 million years ago in the second of two cataclysmic explosions that spewed more than 16 times as much material as Mount St. Helens.
His "Piazzola Caldera" broods.
Krakatoa (Krakatau), Sunda Strait, Indonesia 2,667 813 1680 In 1883 a series of tremendous explosions collapsed the island of Krakatoa; since 1927 a new cone, Anak Krakatau ("Son of Krakatoa"), has risen from the submerged caldera of the old volcano.
