Eruption of Krakatoa in 1883

First fruits

Until this fateful day, Krakatoa is an island that is nine kilometers long and five kilometers wide. It is covered with lush vegetation typical of the humid tropics, but already an intense seismic activity is felt in the region of the volcano, as far as Australia .

Sleeping since 1681 , Perboewatan wakes up on May 20 , 1883emitting plumes of steam and ash up to six kilometers high and audible sound to Batavia , present-day Jakarta . The activity decreased for a few weeks, but on June 19 , new explosions occurred, and on July 20 a new cone was likely formed between Perboewatan and Danan. On August 11 , the activity is still gaining intensity with plumes rising in no less than eleven distinct points. The boats continue to cross the Strait of the Sunda : the one that passes August 14 sails in the dark for four hours, so ash emissions are thick.

Procedure

The eruption begins on August 26 , 1883at 13 hours local time ( UTC +7): a violent explosion is heard more than fifty kilometers from the volcano, followed by another, even stronger around 14 hours, then a series of detonations constantly more violent until 17 hours ¹ . The 14-hour explosion is accompanied by abundant projections of ashes propelled up to over twenty-seven kilometers in height and another part falling, covering everything within a radius of 160 kilometers around the Krakatoa, plunging the region into a total night ¹ .

At 10:02 am, on August 27th , finally comes an appalling explosion: it is the loudest sound ever heard, the force of the explosion is about 10,000 times greater than that of the atomic bomb launched on Hiroshima and shockwaves travel the world seven times ² . The explosion is audible in all the Dutch East Indies, of course, but also in Alice Springs in central Australia and Rodrigues Island in the southwestern Indian Ocean , at 3,500 and over. 4,800 kilometers from Krakatoa ². 160 kilometers away, it still reaches 180 decibels ³ . All persons are within 20 kilometers become totally or partially deaf and persons located within 160 km all suffer persistent hearing impairments ⁴ . The Pliny eruptionreaches level 6 on the volcanic explosive scale , develops an energy corresponding to 13,000 Hiroshima bombs and expels between ten and twenty cubic kilometers of matter into the atmosphere.

Colossal waves – perhaps as tall as a coconut palm – rippled several times on August 26 and 27 on the coasts of Java and Sumatra . In the lower regions bordering the strait probe, is scanned all destroyed, twisted, carried ^one . At Merak , a wave of forty-six meters sweeps over the city; when she retires, there is no indication that the place has been inhabited. At Teluk Betung, a major port in the Sumatra region, the water rises twenty-two meters, leveling everything ¹ . An abnormal oscillation of water is recorded by tide gauges into the Bay of Biscay and Channel ⁵to 18,000 kilometers from the place of the disaster ¹ . It was probably caused by an air shock waveresulting from the explosion because it occurred too early to be a tsunami remnant . These shock waves have circulated several times around the globe and are still detectable using barographs five days later ⁶ .

Around noon, a rain of hot ashes falls around Ketimbang in Sumatra and a thousand people are killed by these fallout, not counting the victims of successive tsunamis ¹ . This unique event would be due, according to Verbeek and other historians and scientists, to a side-blast or a hot flush along the water similar to those of Mount Pelee in 1902 and Mount St. Helens in 1980 , although that the north-west of Ketimbang is spared thanks to the protection provided by the island of Sebesi ¹ .

Lower eruptions occur until mid-October. Verbeek denies evidence that the volcano was active months after the main explosion, putting them on the account of the vapors from rocks still hot, landslides caused by a particularly intense monsoon and hallucinations caused by phenomena electric ⁷ . Finally, no new eruptions occurred until 1913 and the island of Krakatoa has almost entirely disappeared, leaving only the disemboweled cone of Rakata to the south.

Causes of eruption

The causes of eruption violence are the subject of four different theories. Contemporary researchers explained that the volcano would be driven into the sea on the morning of August 27, letting water flood the magma chamber and causing a series of phreato-magmatic explosions massive ¹ . Or the sea water, without being in direct contact with the magma , would however have cooled and hardened causing a ” pressure cooker ” effect, releasing all the accumulated energy only when the sufficient pressure was reached ^1 , 8. These two theories assume that the island collapsed before the explosions; however, there is no evidence to support this conclusion and the pumice stones and ignimbrite deposited are not compatible with an interaction between magma and seawater ¹ . Another hypothesis assumes that a massive underwater collapse or a simple partial weakening, would suddenly open the room magmatiquement highly pressurized ¹ . The last explanation states that the final explosion is due to a magmatic mixture caused by a sudden infusion of basaltic magmahot in the magma colder and lighter of the room. The result would have been a fast and unbearable buildup of pressure, resulting in a cataclysmic explosion. The proof of this theory is the existence of pumice made of light and dark materials, witnesses of an important thermal origin. Nevertheless, the quantity of these materials would be less than 5% of the ignimbrite volume of Krakatoa and for this reason some researchers reject this explanation as an essential cause of the explosion of August 27 , 1883¹ .

Consequences

The human toll is heavy: the Dutch authorities estimate the total number of victims at 36,417. This is the most deadly volcanic eruption in history after that of Tambora , also in Indonesia , in 1815 . Many settlements are destroyed, including Teluk Betung and most of Ketimbang in Sumatra, Sirik and Semarang in Java. The areas of Banten and Lampung are devastated. Documents report the presence of skeletons floating across the Indian Ocean to Africa on pumice rafts a year after the eruption ¹. Some areas in Java have never been repopulated and returned to the jungle, so the Ujung Kulon National Park was created in a perimeter including the Krakatoa and its waters.

The affected areas have been under the administration of the Dutch East Indies for several years now. British journalist Simon Winchester writes that relations between the communities Muslim and Christian are very tense ⁹ . Religious authorities in West Java, especially under the leadership of the sultans , are very strict and show increasing hostility vis-à-vis the settlers during the xix ^th century ¹⁰ . Convinced that a Crusade ( Perang Salib ) is in progress ¹¹, they do not hesitate to preach in Islamic schools ( pesantren ) the return of the “lost sheep” of Java and Sumatra in the bosom of Islam ¹² . Under these conditions, the desolate situation following the eruption catalyzes the outbreak in the affected areas of anti-Western deadly wave by Muslim fundamentalists , one of the first in history ¹³. Experts in Indonesian Islam do not cite anything about this and these claims could include many inaccuracies. Indeed, at the time, there was no “Christian community” in West Java, except for the small European population of cities. There were no settlers but Dutch colonial officials. Moreover, traditionally in Java, there are no religious authorities but kyai , that is to say teachers in religion. Finally, there was no longer any sultan in West Java since the dissolution of the Banten Sultanate in 1813.

The volcanic ash plume rose eighty kilometers into the atmosphere and released enough particles to lower the average global temperature by 0.25 ° C the following year, with an amplitude ranging from approximately 0.18 to 1.3 ° C ¹⁴ . Climate models continue to be chaotic for a few years, and temperatures do not return to normal until after 1888 . The eruption emitted an unusual amount of high sulfur dioxide into the stratosphere all around the planet. The concentration of sulfuric acid increased in the cirrus , increasing the albedoclouds and reflection of incident solar rays until it falls back into acid rain ¹⁴ . These dusts are also at the origin of the flamboyant sunsets, then red wine-lie that inspired many artists, like William Ashcroft with his hundreds of chromolithographs or Edvard Munch with The Scream in 1893 ^15 , 16 , as well as unusually bright colors of the moon as in London . In several cities in the United States , glowing lights are being taken for fires and firefighters are being called in. These phenomena of noctilucent cloudsThe majority of ice-based compounds are caused by diffraction of light by the sprayed lava particles in the stratosphere and occur for about three years.

The eruption also changes the nature of the soils on some nearby islands. Only a year after the cataclysm, grass is already on the tips of islets spared. Two years later, twenty-six species of plants grow there and in 1924 , these fragments of earth are covered with a dense forest. Nearby areas like Lampung, almost barren before the eruption, become very fertile. This attracts a large population.

Notes and references