Nature
PUBLISHED
The Earth is a very noisy place, particularly, I find, in the quiet train carriages. But what is the loudest sound ever recorded on Earth? That came on May 20, 1883, in an event so loud it could be heard 4,800 kilometers (3,000 miles) away.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.First up, the loudest sound was not the result of human activity nor Brian Blessed. The loudest noise caused by humans occurred on October 30, 1961, when the Soviet Union set off Tsar Bomba, the largest nuclear bomb ever detonated. At 50 megatons, the bomb was around 3,800 times more powerful than the "Little Boy" bomb the US dropped on Hiroshima towards the end of World War II. When that bomb was detonated, it produced a noise of around 224 decibels (dB). For context, the sound of your own breathing clocks in at around 10dB, with an electric drill making a noise of around 95dB.
The loudest noise produced by an actual human is actually pretty impressive; a teacher in Belfast who yelled the word "quiet" at an 121.7 dB in 1994, to demonstrate her unusual skill. However, that doesn't mean that Tsar Bomba was only a little bit louder than a primary school teacher, as decibels are logarithmic rather than linear. If something is 20dB louder than another noise, that means it is 100 times as loud; 60 dB higher, and we're talking a noise that is 1,000,000 times louder.
But what is the loudest noise ever recorded? Of course, it is a natural disaster, but it is difficult to pin down which one. The two main candidates are the Tunguska Event, the largest impact recorded in history, and the eruption of Krakatoa.
At around 7:14 am on June 30, 1908, a giant explosion occurred above the Podkamennaya Tunguska river in what is now Krasnoyarsk Krai, Russia. The explosion hit with an estimated force of around 10-20 megatons, making it thousands of times more powerful than the aforementioned "Little Boy" dropped on Hiroshima.
As well as flattening an area of forest the size of London, the blast could be heard like a cannon shot 1000 kilometers (620 miles) away. People closer to the blast, but still as far as 60 kilometers (37 miles) away were reportedly knocked off their feet by the shockwave.
Tunguska came in at an estimated 300 dB, which is nuts when you really keep in your head that we're talking a logarithmic scale here. That makes it 1029 louder than a whisper, or, to use a more useful analogy, 1016 times louder than a jet engine.
But it is likely not the loudest event ever recorded, with that title going to the devastating eruption of Krakatoa, an explosion so powerful it changed the color of the Moon and the Sun in our sky. When it exploded, it did so with the force of a 200-megaton bomb, claiming around 60,000 human lives as it did so.
It also claimed a lot of ear drums. At 160 kilometers (100 miles) away, the sound was still a whopping 172 dB, enough to do some serious damage to your ears.
"So violent are the explosions that the ear-drums of over half my crew have been shattered," the captain of the British ship RMS Norham Castle, around 64 kilometers (40 miles) away, wrote of the noise. "My last thoughts are with my dear wife. I am convinced that the Day of Judgement has come.”
The problem is that the noise was so large it really rubs up against the definition of what we call sound, and is better described as a shockwave, and one that likely traveled around the world three times before it finally petered out. Nevertheless, it is thought to have reached 310 dB. For context, that's around 50 quintillion times louder than what some have claimed to be the loudest fart, which is alleged to have clocked in at a surprising 118.1 dB, in 1970s Michigan.
