forming volcanoes A volcano will form if the magma reaches the surface. When magma does reach the surface it is then called lava.
Volcanoes in the Banda Sea result from subduction of the Pacific Plate under the Eurasia Plate. Black "teeth" are on the overriding plate. Arrows show direction of movement along major transform faults.
Krakatoa creates caldera Krakatau volcano lies in the Sunda strait between the islands of Java and Sumatra. In about 416 A.D., caldera collapse destroyed the volcano and formed a 4-mile (7-km) wide caldera.
The eruption and collapse of the caldera in 1883 produced one of the largest explosions on Earth in recorded time and destroyed much of Krakatau island, leaving only a remnant. earth-shaking explosion
ash rises over Krakatau In 1960 scientists visited Anak Krakatau to record its renewed activity and to measure changes in the size and shape of the island. They observed explosive eruptions of pyroclasts from ash to boulders in size. A column of ash rising above Rakata, a remnant of the volcano prior to the 1883 eruption, is in the background.
four years of explosions Explosive eruptions occurred at half to 10-minute intervals. The largest explosions produced turbulent clouds of ash that rose 4,000 feet above the vent. In this photo a column of ash is rising about 1,500 feet (450 m) above the crater.