Anak Krakatoa () is a volcanic island in Indonesia. On 29 December 1927, Anak Krakatoa first emerged from the caldera formed in 1883 by the explosive volcanic eruption that destroyed the island of Krakatoa. There has been sporadic eruptive activity at the site since the late 20th century, culminating with a large underwater collapse of the volcano that caused a deadly tsunami in December 2018. There has been subsequent activity since. Due to its young age, the island is one of several in the area that are of interest to, and the subject of extensive study by, volcanologists. History Background After the cataclysmic eruption of Krakatoa in 1883, Krakatoa Island lost approximately two-thirds of its body on the northwest side, obliterating the peaks of Perbuwatan and Danan, and leaving only the southern half of the island, including the Rakata volcano, as the last remnant of the original island. The lost area became a shallow sea. Regrowth In early 1927 volcanic activity began to appear at the point located between where the former peaks of Mount Perboewatan and Mount Danan had been. This was a short-lived appearance of a small island that was sunk by sea waves within a week. Several months later, volcanic activity began to create a more permanent land formation that, due to rain and waves, once again collapsed under the sea after its volcanic activity stopped. This process repeated several times during the next three years. On 11 August 1930, the volcanic island permanently rose above sea level, and was locally named Anak Krakatau (or "Child of Krakatoa"). It has been the site of repeated eruptive episodes ever since. Anak Krakatoa's highest point increased at an average rate of 7–9 meters per year through September 2018. Geography Anak Krakatoa is located in the Sunda Strait—between the islands of Java and Sumatra—in the Indonesian province of Lampung. The volcano is contained within the Ujung Kulon National Park, and is part of the Pacific Ring of Fire. Geology The island is situated approximately north of the Sunda Trench marking the subduction zone separating the Australian Plate and the fixed Sunda Plate, atop an oceanic crust of less than in thickness. In geologic terms, it has recently formed within the caldera of the Krakatoa volcanic eruption. The entire island comprises a Somma-stratovolcano system of the late Holocene epoch, and features a pyroclastic cone. The major rock-type components of Anak Krakatoa