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1883 eruption of Krakatoa
The 1883 eruption of Krakatoa in the Dutch East Indies (now Indonesia) began in the afternoon of August 26, 1883 (with origins as early as May of that year), and culminated with several destructive eruptions of the remaining caldera. On August 27, two-thirds of Krakatoa collapsed in a chain of titanic explosions, destroying most of the island and its surrounding archipelago. Additional alleged seismic activity continued to be reported until February 1884, though reports of those after October 1883 were later dismissed by Rogier Verbeek's investigation. It was one of the deadliest and most destructive volcanic events in recorded history, with at least 36,417 deaths being attributed to the eruption itself and the tsunamis it created. Significant additional effects were also felt around the world.
==Early phase==
In the years before the 1883 eruption, seismic activity around the volcano was intense, with earthquakes felt as far away as Australia. Beginning 20 May 1883, steam venting began to occur regularly from Perboewatan, the northernmost of the island's three cones. Eruptions of ash reached an estimated altitude of 6 km (20,000 ft) and explosions could be heard in New Batavia (Jakarta) away. Activity died down by the end of May, and there was no further recorded activity for several weeks.
Eruptions started again around 16 June, featuring loud explosions and covering the islands with a thick black cloud for five days. On 24 June, a prevailing east wind cleared the cloud, and two ash columns were seen issuing from Krakatoa. The seat of the eruption is believed to have been a new vent or vents which formed between Perboewatan and Danan. The violence of the ongoing eruptions caused tides in the vicinity to be unusually high, and ships at anchor had to be moored with chains as a result. Earthquake shocks began to be felt at Anyer, Banten, and ships began to report large pumice masses appearing in the Indian Ocean to the west.
On 11 August, a Dutch topographical engineer, Captain H. J. G. Ferzenaar, investigated the islands. He noted three major ash columns (the newer from Danan), which obscured the western part of the island, and steam plumes from at least eleven other vents, mostly between Danan and Rakata. When he landed, he noted an ash layer about thick, and the destruction of all vegetation, leaving only tree stumps. He advised against any further landings. The next day, a ship passing to the north reported a new vent "only a few meters above sea level." (This may be the most northerly spot indicated on Ferzenaar's map.) Activity continued through mid-August.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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