Rakata ( ), also called Greater Krakatau, is a partially collapsed and uninhabited

stratovolcano A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...

on the

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

island An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been ...

Krakatoa Krakatoa (), also transcribed (), is a caldera in the Sunda Strait between the islands of Java and Sumatra in the Indonesian province of Lampung. The caldera is part of a volcanic island group (Krakatoa archipelago) comprising four islands. Tw ...

() in the

Sunda Strait The Sunda Strait () is the strait between the Indonesian islands of Java island, Java and Sumatra. It connects the Java Sea with the Indian Ocean. Etymology The strait takes its name from the Sunda Kingdom, which ruled the western portion of Ja ...

between the islands of

Sumatra Sumatra () is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi. ...

and

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

. Standing tall, it was the largest and southernmost of three volcanoes that formed the island Krakatoa (the others being Danan (volcano) and Perboewatan) and the only one not totally destroyed in the 1883 eruption. Rakata is the last remnant of the original island prior to its destruction. However, 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 terminating in a large lenticular extrusion at the middle of the almost vertical cliff. The feature has been called "the Eye of Krakatoa."

Etymology

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 that island. But Krakatau is also used for the volcanic edifice as a whole, including all four islands ( Krakatau,

Anak Krakatau Anak KrakatauEnglish translation and common name: ''Child of Krakatoa'' is a volcanic island in Indonesia. On 29 December 1927, Anak Krakatau first emerged from the caldera formed in 1883 by the explosive volcanic eruption that destroyed the ...

, Verlaten and

Lang Lang may refer to: *Lang (surname), a surname of independent Germanic or Chinese origin Places * Lang Island (Antarctica), East Antarctica * Lang Nunatak, Antarctica * Lang Sound, Antarctica * Lang Park, a stadium in Brisbane, Australia * Lang, ...

) of the Krakatoa Archipelago. Before 1883 (and in many of the eruption reports), Rakata was just referred to as "the Peak (of Krakatau)."

Physical features

Rakata is a

volcanic cone Volcanic cones are among the simplest volcanic landforms. They are built by ejecta from a volcanic vent, piling up around the vent in the shape of a cone with a central crater. Volcanic cones are of different types, depending upon the nature and s ...

with its northern face being a vertical

cliff In geography and geology, a cliff or rock face is an area of Rock (geology), rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. ...

, exposing much of its eruptive history. More than 25 extrusion dikes have been counted; the largest at the center runs from sea level to 320 meters above and terminates in a large (about 6 meters in diameter), convex form. It is not known if the two are actually related in origin or just coincidental.

The 1883 eruption

Rakata seems to have played a comparatively minor role in the

1883 eruption of Krakatoa Beginning on 20 May 1883, and ending on 21 October 1883, the volcanic island of Krakatoa, located in the Sunda Strait, had repeated, months long Types of volcanic eruptions, volcanic eruptions. The most destructive of these eruptions occurred o ...

. Some reports seem to indicate it started erupting ("venting") in late July, compared to Perboewatan starting in May and Danan in June. (Furneaux mentions an unsourced report that the Peak had collapsed sometime in July.) All eruptive centres of Krakatau have a common source, meaning that they are different vents of a single volcano. The map made by Capt. Ferzaneer from his visit on 11 August shows no eruptive "foci" from Rakata or its slopes (although there are several from the southern part of Danan), but he was not able to investigate the southern or western parts of the island due to the ash cloud blowing in that direction. In his portrayal of the catastrophe, Rogier Verbeek depicts that Rakata's northern half was destroyed, along with the central part of the island, during the largest explosion, which occurred at 10:02 am on 27 August. Verbeek surmised that unlike Danan and Perboewatan, Rakata was not directly above the

magma chamber A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it u ...

, being connected only by a fissure which lay along the cleavage line of the

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

. 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. In surveys made a few months after the catastrophe, Rakata's height is given as 830 m, compared to 820 m before, however this may be due to inaccuracy of the earlier surveys. Verbeek reports that the cleavage was approximately at the old summit. The remnant 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. Due to the severity of the eruption, leaving very little flora and fauna alive, Rakata has been used as a modern study on biological island colonization.

Recent activity

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

seems to be limited to the area that had been between Danan (volcano) and Perboewatan, where Anak Krakatoa has arisen, starting in 1927.

Etymology

Physical features

The 1883 eruption

Recent activity

References

Further reading

See also