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The renowned volcano Krakatau (frequently misstated as Krakatoa) lies in the Sunda Strait between Java and Sumatra. Collapse of the ancestral Krakatau edifice, perhaps in 416 AD, formed a 7-km-wide caldera. Remnants of this ancestral volcano are preserved in Verlaten and Lang Islands; subsequently Rakata, Danan and Perbuwatan volcanoes were formed, coalescing to create the pre-1883 Krakatau Island. Caldera collapse during the catastrophic 1883 eruption destroyed Danan and Perbuwatan volcanoes, and left only a remnant of Rakata volcano. This eruption, the 2nd largest in Indonesia during historical time, caused more than 36,000 fatalities, most as a result of devastating tsunamis that swept the adjacent coastlines of Sumatra and Java. Pyroclastic surges traveled 40 km across the Sunda Strait and reached the Sumatra coast. After a quiescence of less than a half century, the post-collapse cone of Anak Krakatau (Child of Krakatau) was constructed within the 1883 caldera at a point between the former cones of Danan and Perbuwatan. Anak Krakatau has been the site of frequent eruptions since 1927. (Description from the SI/USGS)
Photos of Anak Krakatau, May 17, 1997. Courtesy of Mike Lyvers.
Recent eruptions of Krakatau have been at Anak Krakatau, an island that emerged in 1927. One tourist was killed and five more injured by an explosion at Anak Krakatau in 1993. Anak Krakatau is undergoing relatively quiet periods, lasting at least a couple days, punctuated by periods of nearly continuous eruption. Mike Lyvers visited the volcano on May 17, 1997. Eruptions consist of minor ash emissions, accompanied at times with a few bombs. Lyvers reported that occasional larger explosions sent incandescent ash high into the sky. These larger explosions generated a spectacular displays of volcanic lightning and covered the cone with glowing bombs. No obvious pattern was detected in the intensity of eruption. Source of information: Volcano Listserv, 26 May 1997.
More than 36,000 people were killed by the 1883 eruption of Krakatau, making it one of the deadliest volcanic disasters in historic time.
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 (VEI=6) 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.
Photographs courtesy of and copyrighted by Robert Decker.
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. In 1960, Anak Krakatau had a minimum diameter of about one mile (1.5 km) and was 545 feet (166 m) tall. A crater on the south side of the island was 2,000 feet (600 m) in diameter and contain a growing cinder cone 300 feet (100 m) in diameter and 150 feet (50 m) high. The new cinder cone formed in about a month and can be seen just below the ash column. Verlaten Island, near the top of this photo, is a remnant of the volcano that was destroyed by the 416 A.D. caldera collapse.
Other Sources of Information:
The West Australian, April 3, 1997
Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.