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 islands of Krakatau, Verlaten, and Lang are remnants of this volcano. 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. Since 1927, small eruptions have been frequent and have constructed a new island, Anak Krakatau (Child of Krakatau). Image courtesy of the Landsat Pathfinder Project.
In January of 1960 a group of scientist 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. This photograph shows a column of ash rising above the island. Rakata, a remnant of the volcano prior to the 1883 eruption, is in the background.
Explosive, Vulcanian-type eruptions occurred at 1/2- to 10-minute intervals. The largest explosions produced turbulent clouds of ash and lapilli that rose 4,000 feet (1,200 m) above the vent. In this photo a column of ash is rising about 1,500 feet (450 m) above the crater. This episode of activity, which began in December of 1959, ended in 1963. Anak Krakatau has had at least nine episodes of activity since 1963, most lasting less than one year. The most recent episode began in March of 1994 and has continued to at least March of 1995 (last reported observation). Activity is similar to the 1959-1963 eruption
ETNA
In mythology, Etna was identified as the location of the forge of Volcan, home of the Cyclopses, and where the giant Enceladus laid (eruptions being his breath and earthquakes his motion). Etna's beauty, frequent eruptions, and long record of eruptions makes it one of the world's best known volcanoes. With hundreds of papers published on nearly every aspect of Etna's geology it is probably one of the world's most studied volcanoes.
Etna is one of the largest continental volcanoes. The base of the volcano is about 36 by 24 miles (60 x 40 km). Below an elevation of about 9,500 feet (2,900 m) Etna is a shield. The upper 1,200 feet (400 m) is a stratovolcano made of several coalesced vents. Much of the surface of the volcano is covered by historic lava flows. Most eruptive products are made of andesite. The eruption rate of Etna is about one-sixth that of Kilauea.
