Height: 813 m above sea-level
More than a million years ago in Indonesia to the west of Java was a conical volcano. Over the years, eruptions have destroyed the tip. The new cones have grown over the surface of the sea and the island of Krakatau formed with a height of 813 m and a length of 9 km.
The eruption 416
Probably about 416, the n.e. was the collapse of the original volcano and caldera formed 7-kilometer length. The remains of this former volcanic island formed Verlaten and Lang.
Later formed three, lying in the central part of the caldera volcanoes: Rakata, Danan and Perbuwatan. Their craters rose side by side on one line and form an island volcano – Krakatoa.
Since 1878, felt more and more frequent and stronger earthquakes in the Bay area, western Java and eastern Sumatra.
September 1, 1880 a strong earthquake damaged the lighthouse “First Point” on the west coast of Java (70 km southeast of Krakatoa). Subsequent shocks were felt between 9-10 May 1883 and 15-20 May 1883 Katimbang year.
20 May 1883 eruption began with Perbuwatan crater. Fine ash and steam and gases are continuously mined over the next 3 months. At that time, opened a dozen or so, constantly active, escape of gases within the volcano. Until then, the eruption recurred periodically. After a period of volcanic activity to a halt. At that time, sea water infiltrating the gaps and cracks into the volcano and was the source of steam. Aug. 11 rose a cloud of violent eruption of ash and gases from the crater Perbuwatan and Danan, and then created a number of holes and crevices. Eruptions escalated on August 24, 1883. (Verbeek, 1886, Judd, 1888; Simkin and Fiske, 1983)
27 August 1883 year, there was one of the largest recorded volcanic eruption (and also of all natural disasters) in the history of mankind. The roar could be heard from a distance of 3200 km. Began on 26 August at 12:53 local time. At night, explosions were heard from a distance of 4325 km. The column of smoke, ash and gases reached 27 km altitude. Decks of ships in the Strait of Sunda were inundated with ash, dust and pieces of pumice with a diameter of about 10 cm. Between the hours. 18:00 and 19:00 a small tsunami waves spread concentrically and hit the distant coast by up to 40 km.
August 27 at 5:30, 6:42 and 8:20 local time there were more eruptions. Each of them has caused devastating tsunami waves. Last explosion occurred about 10:02. Volcano threw up in the air 19 km ³ (some sources give values up to 25 km ³) of ash to a height 55 km, that is, into the stratosphere. On the island of Rodrigues in the Indian Ocean, 4800 km away, residents have seen on the horizon ashes and sparks.
The explosion of Krakatoa caused record for the loudest and recorded the distance traveled by the sound. Shock wave created by the explosion moves at a speed of more than 1100 km / h. It is estimated that the sound level at a distance of 160 km from the epicenter was over 180 decibels.
2 / 3 of the island disappeared from the face of the earth, and of the remainder (Rakata) life has been completely destroyed. Tsunami wave heights up to 40 meters and speeds over 700 km / h, washed off the local village on a nearby shore and went around half of the Earth, before completely disappeared. Ships off the coast of South Africa zachybotały result in tsunami-induced eruption. Seismic wave went around the Earth seven times. Probably killed around 40 thousand people (there are no exact data). Floating on the ocean surface bodies of victims were found by a few weeks after the disaster. Gases released into the atmosphere made it for about 3 years the Sun as seen from Earth, was the color green, and blue moon. It is estimated that the explosion was about 200 megatons of power of TNT and a total of blurted out 46 km ³ of dust which covered a total of sinking 70% of the world.
The cause of the tsunami was probably drained piroklastyczne, which moved on the slopes of the volcano and fell into the sea. Each of the five explosions caused piroklastyczny runoff, flowing into the sea which caused the displacement of an equal volume of water, which is a few km ³ each. Found traces of underwater runoff piroklastycznych just 15 km from Krakatau. In addition, recent studies of German scientists have shown that moving at high speed, pyroclastic material penetrating runoff to the sea in the form of ash and gas at 1200 degrees Celsius even floats on water vapor as a pillow. In this way, probably destroyed part of the coast of Sumatra distant about 40 miles from the island.
After the Krakatoa explosion in 1883 left three islands, of which one remained active volcano. In 1930 this place has emerged an active volcanic mountain today (about 320 m high) bearing the name of Anak Krakatau (“Child Krakatoa”).
Cone of the volcano continues to grow at a rate of about 5.1 m per year. Currently has a height comparable to that of the old Krakatoa. Wounded so far four people and killed one person (data 2006). Established a ban on approaching the volcano within a radius of 3 km.
Back to life on Anak Krakatau and Rakata
Little is known about the fauna that lived Krakatau before 1883. The eruption destroyed the island of all living organisms. Yes sterilized the area became a target of the biogeografów.
Since May 1884 a French scientific expedition began the search for life on Rakacie. Discovered only one spider with a very small scale. Waterway to the shores of the island began to pass crabs. Approximately 1899 of the nearby islands escaped stripe Waran (Varanus salvator), and later python mesh (Python reticulatus).
In the 80s Nineteenth century, biologists have shown that Anak Krakatau and Rakata are regularly inhabited by various species of arthropods comprising the aeroplanktonu. The presence of 72 species. In subsequent years, the islands were colonized by various groups of plants and animals, the sequence of their appearance was coincidental. In 1928 there were nearly 300 species of grasses and shrubs. Many species of animals, especially vertebrates, extinct shortly after the arrival of the Rakata.
In the years 1984-1985 found 30 species of land birds, 11 – mammals (including 9 species of bats), 9 – reptiles and over 600 species of invertebrates. Biodiversity has reached the volume level comparable to other islands of this type after about 100 years after the eruption in 1883, but the species composition is characterized by less stability.