On August 27, 1883, at 10:02 a.m., an island in Indonesia collapsed due to tsunamis caused by waves of 46 meters breaking through the ocean to South Africa. This was the point at which the famous Krakatoa volcano erupted, initiating what is thought to be the loudest noise ever.
Krakatoa once sat midway between Java and Sumatra in Indonesia. It was a small, uninhabited volcanic island that rose 838 meters above sea level and was last believed to have been active in 1680, before rumbles began in 1883.
The August blast unleashed the equivalent of a 200-megaton bomb and had a profound impact on people and the environment, the Natural History Museum reported.
After an eruption at Tambora in 1815 that claimed at least 60,000 lives, Krakatoa was the second deadliest eruption in modern history with 36,000 deaths. The explosion created an extreme fluctuation in air pressure that was perceived as sound at certain intervals.
A barometer recorded at a gas factory 160 kilometers from Krakatoa on that fatal day showed that the explosion produced a sonic boom of 172 decibels at that distance. Human pain threshold is 130 decibels, Nautilus reports, and every 10 decibel increase above it is perceived as a doubling of the noise.
Considering that a rock drill creates about 100 decibels of sound, anyone 160 kilometers from Krakatoa was having a bad time on August 27, 1883. For those who were a little closer, the situation was indeed much more risky.
Since the loudest sound recorded near the blast site was 194 decibels, the loudest possible in air, this air pressure changed from a perceptible sound to a burst of compressed air that burst the eardrums of sailors on a ship 64 kilometers from the island.
Discover states that the captain’s logbook of the British ship Norham Castle wrote, “The explosions were so violent that more than half of my crew had their eardrums shattered,” and adds: “My last thoughts are with my beloved wife. I’m sure the Day of Judgment is coming.”
The same shock wave continued to fly across the planet and became quieter as it moved away, but it took some progress before it slowed down. As Brüel & Kjær reported, it could still be heard like cannon fire from 4,800 kilometers away from Krakatoa.
The pressure wave would continue to wrap around the globe three times in all directions, creating extra pressure spikes with occasional colliding shock waves anywhere on the planet. The “great airwave” continued to circle the planet for a while after it dropped below the human hearing threshold, and then the loudest sound we’ve ever heard ended.
The loudest sound since Krakatoa is believed to be a sonic boom in Tonga in 2022 heard in Alaska, 6,200 kilometers away. In addition, the Tongan explosion created sound waves and tsunamis that circulated around the planet, with a pressure wave traveling at over 1,100 kilometers per hour and reaching an altitude of 450 kilometers (higher than the orbit of the International Space Station).
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