Rakata

From Wikipedia, the free encyclopedia

This article is about the Indonesian volcano. For other uses, see Rakata (disambiguation).

Anak Krakatau, June 2005. Fresh lava flows are clearly visible.Rakata island

Rakata (2667 ft) is a stratovolcano on the Indonesian island of Krakatoa (Indonesian: Krakatau) in the Sunda Strait between the islands of Sumatra and Java. It is the largest, and southernmost, of three volcanoes that formed the island Krakatoa (the others being Danan and Perboewatan) and the only one not totally destroyed in the eruption of 1883. Rakata did lose its northern half in that eruption, leaving just its southern half. The exposed cliff is quite striking visually, partially of a large exposed dike in the middle.

1 Name
2 Eruptions
- 2.1 1883
- 2.2 Later Activity
3 References
4 See also

[edit] Name

For the origin of the name, see Krakatau

Because the words 'Rakata' and 'Krakatau' are the same in Indonesian, both names are used interchangeably; leading to confusion in languages which distinguish between the two words. In geological usage, Krakatau is the island and Rakata is the main volcanic cone on the island. But Krakatau is also used for the volcanic edifice as a whole, including all four islands (Krakatau, Anak Krakatau, Verlaten and Lang).

[edit] Eruptions

There are no dated reports of eruptions from Rakata until the 1883 catastrophe, although tentative datings have been made from dating ash deposits left.

[edit] 1883

Rakata seems to have played a comparatively minor role in the eruption of 1883; reports seem to indicate it started erupting ('steaming') in late July, compared to Perboewatan starting in May and Danan in June. However, it is more proper to realize that all of the eruptive centers of Krakatau have a common source and that we are talking about particular cones of the same volcano, rather than separate volcanoes.

In his reconstruction of the catastrophe, R. D. M. Verbeek has Rakata's northern half destroyed along with the central part of the island in the largest explosion, at 10:02 am, August 27. Verbeek surmised that unlike Danan and Perboewatan, Rakata was not directly above the magma chamber, being connected only by a fissure which lay along the cleavage line of the caldera. However, examining the cliff from the air indicates two arcs, the second of which seems to be due to later (post-1883) landslides of unstable cliff material.

The remmant of Rakata grew rather considerably in area due to falling pumice. However, most of the increased area (largely to the west and southeast) was washed away within several years by wave action.

[edit] Later Activity

Subsequent activity of Krakatoa seems to be limited to the area that had been between Danan and Perboewatan, where Anak Krakatoa has arisen, starting in 1927. Rakata cone seems to be extinct.