Summary

The Krakatoa eruption of 1883 was a cataclysmic volcanic eruption in the Dutch East Indies (now Indonesia) that changed the face of the archipelago where Krakatoa, a grey volcano in the Pacific Ring of Fire, is located in the Sunda Strait between Sumatra and Java.

The paroxysmal eruption begins on August 26, 1883 at 13 hours local (UTC+7) and ends the following day August 27, 1883. This explosive and phreato-magmatic eruption, observed and described by Rogier Verbeek, causes tens of thousands of victims, killed by the shock wave, the fallout of debris and ashes, and the tsunamis following the explosion. It caused a terrible noise, the loudest heard on Earth and recounted by historiography, and generated nocturnal clouds visible even in the skies of Northern Europe, where Edvard Munch reproduced them ten years later in his famous painting The Scream.

Before the eruption, Krakatoa is a volcanic island measuring nine kilometers long and five kilometers wide, located in the Sunda Strait in Indonesia, between Sumatra and Java. It is covered with lush vegetation typical of humid tropical regions, but already intense seismic activity is felt in the region of the volcano, as far as Australia.

Sleeping since 1681, Perboewatan awoke on May 20, 1883, emitting plumes of steam and ash up to six kilometers high and a sound audible as far away as 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 formed in all likelihood between Perboewatan and Danan. On August 11, the activity increases again in intensity with plumes rising in no less than eleven distinct points. However, ships continued to use the Sunda Strait: the one that passed through on 14 August sailed in darkness for four hours, so thick were the ash emissions.

The paroxysmal eruption begins on August 26, 1883 at 13 hours local (UTC+7): a violent explosion is heard at more than fifty kilometers of the volcano, followed by another one, even stronger towards 14 hours, then of a series of detonations unceasingly more violent until towards 17 hours. The explosion of 14 hours is accompanied by abundant projections of ash propelled to more than twenty-seven kilometers high and some of which fall, covering everything in a radius of 160 kilometers around Krakatoa, plunging the region into total darkness.

At 10:02 a.m. on August 27, a frightening explosion finally occurred: it was the loudest noise ever heard in history, the power of the explosion was about 10,000 times greater than that of the atomic bomb dropped on Hiroshima, and the shockwaves travelled the globe seven times. The explosion can be heard throughout the Dutch East Indies, of course, but also in Alice Springs in central Australia and on the island of Rodrigues in the southwestern Indian Ocean, located 3,500 and 4,800 kilometers from Krakatoa respectively. At 160 kilometers away, it still reaches 180 decibels. According to the elevation table

Colossal waves - perhaps as high as a coconut tree - broke several times on the coasts of Java and Sumatra on 26 and 27 August. In the low-lying areas bordering the Sunda Strait, everything was swept away, destroyed, twisted and carried away. In Merak, a forty-six meter wave broke over the city; when it receded, there was no indication that the place was inhabited. In Teluk Betung, a large port in the Sumatra region, the water rises twenty-two meters, leveling everything. An abnormal water oscillation was recorded by tide gauges as far as the Bay of Biscay and the English Channel, 18,000 kilometers from the disaster site. It was probably caused by an air shock wave resulting from the explosion, as it occurred too early to be a remnant of the tsunami. These shock waves circulated several times around the globe and are still detectable with barographs five days later.

Around noon, a shower of hot ash fell around Ketimbang in Sumatra and a thousand people were killed by the fallout, not counting the victims of successive tsunamis. According to Rogier Verbeek and other historians and scientists, this unique event was caused by a lateral explosion or a fiery cloud at water level similar to those of Mount Pelee in 1902 and Mount Saint Helens in 1980, so that the northwest of Ketimbang was spared thanks to the protection provided by the island of Sebesi.

Weaker eruptions took place until mid-October. Verbeek denies reports that the volcano was active months after the main explosion, blaming it on fumes from still-hot rocks, landslides caused by a particularly intense monsoon and hallucinations caused by electrical phenomena. Finally, no new eruption occurs before 1913 and the island of Krakatoa has almost completely disappeared, leaving only the gutted cone of Rakata in the south. On December 29, 1927, underwater eruptions caused the appearance of a new volcanic island, Anak Krakatoa.

The causes of the violence of the eruption are the subject of four divergent theories. Contemporary researchers have explained that the volcano sank into the sea on the morning of August 27, allowing water to flood the magma chamber and causing a series of massive phreato-magmatic explosions. Or the sea water, without being in direct contact with the magma, would have cooled and hardened it, causing a "pressure cooker" effect, releasing all the energy accumulated only when sufficient pressure was reached. Both theories assume that the island collapsed before the explosions; however, there is no evidence to support this conclusion and the deposited pumice and ignimbrite are not consistent with an interaction between magma and seawater. Another hypothesis assumes that a massive underwater collapse, or even a simple partial weakening, would have suddenly opened the highly pressurized magma chamber. The last explanation states that the final explosion was due to magmatic mixing caused by a sudden infusion of hot basaltic magma into the colder, lighter magma of the chamber. The result would have been a rapid and unbearable rise in pressure, leading to a cataclysmic explosion. The evidence for this theory is the existence of pumice made of light and dark materials, evidence of a significant thermal origin. However, 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 the main cause of the explosion of August 27, 1883.

The human toll was high: the Dutch authorities put the total number of victims at 36,417. It was the deadliest volcanic eruption in history after Tambora, also in Indonesia, in 1815. Many settlements were destroyed, including Teluk Betung and most of Ketimbang in Sumatra, Sirik and Semarang in Java. The areas of Banten and Lampung were devastated. Documents report the presence of skeletons floating across the Indian Ocean towards Africa on rafts of pumice stones one year after the eruption. Some areas in Java were never repopulated and reverted to jungle, so the Ujung Kulon National Park was created, within a perimeter that included Krakatoa and its waters.

The affected areas have been under Dutch East Indies administration for several years. British journalist Simon Winchester writes that relations between the Muslim and Christian communities are very tense. The religious authorities in West Java, in particular, under the leadership of the sultans, were very strict and showed increasing hostility towards the settlers during the 19th century. Persuaded that a crusade (Perang Salib) was underway, some did not hesitate to advocate in Islamic schools (pesantren) the return of the "lost sheep" of Java and Sumatra into the fold of Islam. In these conditions, the situation of desolation that follows the eruption catalyzes the triggering in the affected areas of a wave of anti-Western murder by Muslim fundamentalists, one of the first in history. Specialists in Indonesian Islam do not cite anything on this subject and these statements may contain many inaccuracies. Indeed, at the time, there was no "Christian community" in West Java, except for the small European population in the cities. There were no settlers but Dutch colonial officials. In addition, traditionally in Java, there are no religious authorities but kyai, i.e., masters in religion. Finally, there was already no sultan in West Java since the dissolution of the Banten Sultanate in 1813.

The volcanic ash plume rose eighty kilometers into the atmosphere and spread enough particles to lower the average global temperature by 0.25°C the following year, with a range of approximately 0.18 to 1.3°C. Climate patterns continued to be chaotic for a few years, and temperatures did not return to normal until after 1888. The eruption emitted an unusual amount of sulfur dioxide high in the stratosphere all around the planet. The concentration of sulfuric acid increased in the cirrus clouds, increasing the albedo of the clouds and the reflection of incident solar radiation until it fell back as acid rain. This dust is also the source of the flaming, then wine-red sunsets that inspired many artists, such as William Ashcroft with his hundreds of chromolithographs or Edvard Munch with The Scream in 1893, as well as unusually vivid colorations of the Moon as in London. In several cities in the United States, glowing lights were mistaken for fires and the fire department was called in. These phenomena of noctulescent clouds essentially composed of ice are caused by the diffraction of light by the particles of pulverized lava gone up in the stratosphere and manifest themselves during approximately three years.

The eruption also changed the nature of the soil on some neighboring islands. Only one year after the cataclysm, grass was already growing on the tips of spared islands. Two years later, twenty-six species of plants grow there and in 1924, these fragments of ground are covered with a dense forest. Nearby areas such as Lampung, almost sterile before the eruption, became very fertile. That attracts an important population.

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