Chronology of the Krakatau eruption

Chronology of the Krakatau eruption

• From April 20 to May 10, 1883: Violent seismic crisis in South Sumatra and West Java (but at this time there is no link between this seismic activity and Krakatau).

• May 10-19, 1883: The earthquakes intensify causing damage and victims.

• May 20, 1883: After 203 years of sleep, eruption of the small volcanic cone Perbuatan, the sound of the explosion is perceived within a radius of 160km! The height of the eruptive plume reaches 13000 meters. The shockwave stops all the clocks until Jakarta (name of the colonial era: Batavia)

• May 26, 1883: Volcanic activity decreases in intensity. During three days, the height of the eruptive plume stagnates between 1000 and 1500 meters of altitude. Taking advantage of this lull, maritime excursions are organized around the Krakatau.

• May 27, 1883: The Dutch mining engineer Schurman arrives on the island of Rakata / Krakatau (We owe him the first scientific report of this eruption) and declares that there is no longer a leaf on the trees and that 60 centimeters of basaltic black ash cover 30 centimeters of very clear pumice (dacitic). This observation was the starting point for the explanation of the terrible eruption that will follow.

• From May 29 to end of June 1883: recovery of the explosive activity with a height of plume of about 5000 meters.

• July 1, 1883: brutal recrudescence in explosive violence. The eruptive column rises to 18,000 meters then gradually decreases until August 10 when it reaches barely 1,000 meters. During this period, fragments of pumice fall back to 1900 km west of Krakatau. There is a permanent halo around the sun, the moon turns blue.

• August 10, 1883: a captain of the topographic service of the Dutch army, Ferzenaar will be the last person to land on the island of Krakatau. He declares: “All the branches of the trees are broken, the thickness of ash reaches 2.5 m and we perceive some small explosions on the Danan volcanic cone”.

• August 11, 1883: brutal awakening of the Danan volcanic cone. 11 eruptive chimneys simultaneously enter into activity and project their plume to some 6000 m of altitude. This activity will continue until August 26th.

From this date, the reconstruction of the following events is largely based on recordings of measuring devices, volcanic deposits and the testimony of some captains of boats crossing the Sunda Strait or sailing near the coast. from Sumatra (south of Bengkulu) whose boat did not sink! Because no one living near the volcano has survived.

• August 26, 1883:

At 10:00, the eruptive column reaches 11,000 meters.

At 13:00, it rises to 21,000 meters.

At 15:00, 26,000 meters. In the space of 7 hours, a 27 meter layer of ash will fall on the small neighboring island of Sertung (6 centimeters per minute).

• August 27, 1883:

at 5.30 am, the series of huge explosions that will be seen in a radius of 3000 km begin.

at 7:00, the eruptive column reaches 43,000 m in height.

At 9:58, the largest of all the explosions occurs, which will be seen in a radius of 5000 km, where the noise will arrive a little more than 4 hours later. (If this same explosion took place in Paris, it would have been heard both east of Quebec, Kazakhstan or Ivory Coast). The shock wave is so powerful that all the windows shatter within a radius of 500 km, it will travel around the world 7 times! This colossal explosion is accompanied by a huge tidal wave (Tsunami). The height of the wave crashing on the coast of Java and Sumatra, the height is estimated at 47 meters. This huge wave will take 2 hours to reach Batavia the capital (Jakarta today). A gunboat, the Berouw, with 10 crewmembers will be found 5 km inland from Sumatra after climbing over a 15 m hill (see map of tsunami affected areas below). krakatau from 1883). It was noticed, a few days after the eruption, an abnormal rise of waters at Mont Saint-Michel (see books of the town hall, index of the tide of the year 1883).

The height of the volcanic plume reaches 48,000 m. Darkness is total within a radius of 400 km. Pyroclastic flows of pumice and incandescent ash fluidified by the gas move on the surface of the sea over long distances (some 170 km for some) at a speed of 360 km / h or 100m / s. The ashes released by the volcano fall on an area of 700 000 km², the largest fallout area ever recorded. The finest ashes are orbited around the planet and will take more than a year to fall.

14:30, the night is now total within a radius of 600 km around the eruptive center. 4/5 of the area of the island of Krakatau have disappeared. There is nothing left of the Danan and Perbuatan volcanoes and only the eastern part of Rakata. In place of the collapsed island now opens a caldera 290 m deep, under the sea.

At 16:00, the eruption decreases, the height of the eruptive plume is only 25,000 m.

• August 28, 1883: it is the end of the eruption that lasted 39 hours. The balance is heavy. 40,000 victims, hundreds of villages destroyed. The volume of material expelled by the volcano was 20 km3. The energy developed by this eruption corresponds to 100,000 bombs of Hiroshima.

Map of the areas flooded by the tsunami generated by the eruption of KrakaTau in 1883