The Eruption That Shook The World: Krakatoa

Aug 31, 2022 | Deadly Earth

August 31, 2022
8 min read

At 10:02 am, on August 27th, 1883, an explosion equaling 200 megatons of TNT, rocked the world. This explosion was roughly four times stronger than the Tsar Bomba (the biggest bomb ever made), or 10,000 times stronger than the bomb dropped on Hiroshima. This explosion, however, was not man made. It was the result of the eruption of Krakatoa.

In the Sunda Strait, between the islands of Sumatra and Java in western Indonesia, sits Krakatoa (Krakatau in Indonesian), a small volcanic archipelago. After 200 years of dormancy, in May of 1883, the volcano Krakatoa began to awaken.

Early Warnings

It started with small tremors, earthquakes felt in Sumatra, about 25 miles north of the volcano. Throughout the month, they began to grow stronger, and the eruptions became more frequent as ash began to fall in Sunda Strait. Windows rattled, clocks stopped, and explosions could be heard up to 150 miles away.

Sunda Strait Map. Telim tor, Public domain, via Wikimedia Commons

Locals were reportedly not alarmed by the eruptions and earthquakes as this was not a rare occurrence in the area.

By the end of May, ash was falling up to 228 miles away, and unusual atmospheric conditions, like solar halos and blue moons (ash in the atmosphere causing red light to scatter and make the moon appear literally blue) were reported almost 1,875 miles to the northwest.

June 16th, a booming explosion was heard and thick smoke covered the area for several days. It cleared about a week later, and two eruption columns were seen coming out of the volcano. Fields of floating pumice stone covered miles of the Indian Ocean.

After a few months of activity, in early August the dutch topographer Captain Ferzenaar came to study the volcano. He noted some areas that were devastated, where trees had been reduced to stumps, and found three active craters where steam rose out. It appeared that part of the main crater had collapsed recently.

Due to his findings, he reported that:

“Measuring there is still too dangerous; at least I would not like to accept the responsibility of sending a surveyor… I consider a survey on the island itself inadvisable”.

Dutch Topographer Captain H. J. G. Ferzenaar

Sure enough, the volcanic activity increased quickly. Ships reported a two-mile-high column of ash over the volcano, the amount of pumice stones in the ocean grew, and explosions were heard. This activity reached a climax on August 26th and 27th.

The Loudest Sound in History

On August 26th, at about 10am, ash began falling in the city of Jakarta. At 1pm a series of explosions were heard, and the sea level began to fluctuate. At 2pm was a huge explosion that caused the eruption column to reach 16 miles high. Pyroclastic flows and surges flew into the bay as the explosions increased in intensity.  

Through the remainder of the day, sounds like cannon fire and thunder were heard up to 375 miles away. An explosion recorded on a pressure gauge at Jakarta Gasworks at 3:34pm, and a small tsunami occurred at 3:37pm.

On the morning of August 27th, at 10:02am, the strongest eruption occurred, resulting in several devastating impacts. The explosion produced the loudest recorded sound in history, that could be heard up to 3,000 miles away, and by almost 1/13 of the world’s surface. The air waves from this sound were detected by devices around the world, circling the Earth seven times, making it the farthest travelling sound in recorded history.

27th May 1883: Clouds pouring from the volcano on Krakatoa Royal Society Report on Krakatoa Eruption — pub. 1888 Lithograph. Lithograph: Parker & Coward, Britain;, Public domain, via Wikimedia Commons

A captain of a British ship about 40 miles from the explosion said:

“So violent are the explosions that the ear-drums of over half my crew have been shattered. My last thoughts are with my dear wife. I am convinced that the Day of Judgement has come.”

Captain Sampson of the Norham Castle

Devastating After Effects

A dust cloud produced by the explosion threw the area within 50 miles of Krakatoa into total darkness for over two days.

The 10:02am explosion triggered a massive tsunami, the effects of which were felt as far away as Alaska and the English Channel. The Royal Society Report of the time estimated the height to be about 50 feet in height, although eyewitnesses claim it was between 100 – 135 feet high. Modern estimates place the height of the tsunami as over 100 feet high.

This tsunami killed 36,417 people, and at least 1,000 people died from superheated volcanic ash, making this one of the deadliest volcanic events in recorded history. Bodies of victims were found floating in the ocean for weeks, and human skeletons washed up on beaches on the east coast of Africa for up to a year.

Long term, dust particles and ash from the explosion trapped in the atmosphere caused vivid red sunsets around the world for months afterwards. It’s been said that the background of Edvard Munch’s famous 1893 painting “The Scream” captures one of these incredible sunsets in Norway.

The Scream, 1893. Edvard Munch, Public domain, via Wikimedia Commons

Scientists have since been able to explain the devastating eruption of Krakatoa. The volcano sits at the point where the Indo-Australian and Asian tectonic plates collide in a subduction zone.

Krakatoa Today

In the crater left behind by the eruption of Krakatoa, a new volcano rose from the sea on December 29, 1927: Anak Krakatoa, literally translated as “Child of Krakatau”. True to its lineage, there has been sporadic volcanic activity since it’s birth. In December of 2018, it caused a deadly tsunami.

Anak Krakatau. flydime, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons

Let’s hope that Anak Krakatoa doesn’t try to beat its parent’s records.

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