Krakatoa, also transcribed Krakatau, 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 comprising four islands. Two, Lang and Verlaten, are remnants of a previous volcanic edifice destroyed in eruptions long before the famous 1883 eruption; another, Rakata, is the remnant of a much larger island destroyed in the 1883 eruption.
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
Mount Tambora, or Tomboro, is an active stratovolcano in West Nusa Tenggara, Indonesia. Located on Sumbawa in the Lesser Sunda Islands, it was formed by the active subduction zones beneath it. Before 1815, its elevation reached more than 4,300 metres high, making it one of the tallest peaks in the Indonesian archipelago.
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica, with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as 15 km (9.3 mi).
The Indonesian island of Java is almost entirely of volcanic origin, and contains numerous volcanoes, 45 of which are considered active volcanoes. As is the case for many other Indonesian islands, volcanoes have played a vital role in the geological and human history of Java. Indeed, land is created on Java as a result of lava flows, ash deposits, and mud flows (lahars). Volcanoes are a major contributor to the immense fertility of Java, as natural erosion transports volcanic material as alluvium to the island's plains, forming thick layers of fertile sediment. The benefit is not just in the immediate vicinity of the volcano, with fine ash emitted from eruptions being dispersed over wide areas.
Mount Merapi, Gunung Merapi, is an active stratovolcano located on the border between the province of Central Java and the Special Region of Yogyakarta, Indonesia. It is the most active volcano in Indonesia and has erupted regularly since 1548. It is located approximately 28 km (17 mi) north of Yogyakarta city which has a population of 2.4 million, and thousands of people live on the flanks of the volcano, with villages as high as 1,700 m (5,577 ft) above sea level.
Mount Rinjani is an active volcano in Indonesia on the island of Lombok. Administratively the mountain is in the Regency of North Lombok, West Nusa Tenggara. It rises to 3,726 metres (12,224 ft), making it the second highest volcano in Indonesia. It is also the highest point in the Indonesian province of West Nusa Tenggara.
Paluweh, also known as Rokatenda, is a stratovolcano that forms the small island of Palu'e, north of Flores Island in Sikka Regency in the province of East Nusa Tenggara, Indonesia. While the volcano rises about 3,000 m (9,840 ft) above the sea floor, its cone rises just 875 metres (2,871 ft) above sea level and is the highest point on the island.
Kelud is an active stratovolcano located in Kediri, East Java, Indonesia. Like many Indonesian volcanoes and others on the Pacific Ring of Fire, Kelud is known for large explosive eruptions throughout its history. More than 30 eruptions have occurred since 1000 AD. In 2007, an effusive explosion filled the crater with a lava dome. It last erupted on February 13, 2014, destroying the lava dome and ejecting boulders, stones and ashes up to West Java about 500 kilometers from Mount Kelud. The crater filled with water during the rainy season.
Mount Cleveland is a nearly symmetrical stratovolcano on the western end of Chuginadak Island, which is part of the Islands of Four Mountains just west of Umnak Island in the Fox Islands of the Aleutian Islands of Alaska. Mt. Cleveland is 5,675 ft (1,730 m) high, and one of the most active of the 75 or more volcanoes in the larger Aleutian Arc. Aleutian natives named the island after their fire goddess, Chuginadak, who they believed inhabited the volcano. In 1894 a team from the U.S. Coast and Geodetic Survey visited the island and gave Mount Cleveland its current name, after then-president Grover Cleveland.
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.
A somma volcano is a volcanic caldera that has been partially filled by a new central cone. The name comes from Mount Somma, a stratovolcano in southern Italy with a summit caldera in which the upper cone of Mount Vesuvius has grown.
Mount Raung is one of the most active volcanoes on the island of Java in Indonesia. It is located in the province of East Java and has a 2-kilometer-wide (1.2 mi) and 500-meter-deep (1,600 ft) caldera surrounded by a grayish rim. The difference in color of the rim and the flanks of the volcanoes is caused by the rim’s lack of vegetation compared with the healthy and extensive vegetation on the flanks. Raung, standing almost 3,332 metres (10,932 ft) above sea level, is the tallest volcano of this cluster.
A complex volcano, also called a compound volcano or a volcanic complex, is a mixed landform consisting of related volcanic centers and their associated lava flows and pyroclastic rock. They may form due to changes in eruptive habit or in the location of the principal vent area on a particular volcano. Stratovolcanoes can also form a large caldera that gets filled in by a lava dome, or else multiple small cinder cones, lava domes and craters may develop on the caldera's rim.
Poco Mandasawu is a lava dome of Ranakah located in the south-central part of the island of Flores, Indonesia. It is the highest point of the island.
Soputan is a stratovolcano in Indonesia. It is on the northern arm of Sulawesi island and rises to an elevation of 1,785 m (5,853 ft). The geologically young and mostly unvegetated cone is primarily constructed of andesite and basalt rock. It sits on the southern rim of the Tondano caldera, which formed in the Quaternary period. The volcano is one of Sulawesi's most active, with 39 confirmed eruptions in the last 600 years. Eruptive activity at Soputan typically consists of pyroclastic flows, lava flows, lava domes and Strombolian-style explosions.
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from 800 to 1,200 °C. The volcanic rock resulting from subsequent cooling is also often called lava.
The Krakatoa Archipelago is a small uninhabited archipelago of volcanic islands formed by the Krakatoa stratovolcano located in the Sunda Strait, nestled between the much larger islands of Java and Sumatra. As of 2018, the archipelago consists of four main islands: Verlaten, Lang, Rakata, and the currently volcanically active Anak Krakatoa. Together, the islands are a part of the Indonesian island arc system, created by the northeastward subduction of the Indo-Australian Plate. As part of a dynamic volcanic system, the islands have been continuously reshaped throughout recorded history, most notably in the 1883 eruption of Krakatoa.
