Krakatoa Eruption

The loudest sound ever recorded was an 1883 volcanic eruption on the Indonesian island of Krakatoa, clocking in at an estimated 310 decibels. Not that anybody who heard the explosion at full blast lived to tell the tale; it was estimated to have a force equivalent to 10,000 times that of the atomic bomb dropped on Hiroshima, Japan, in 1945, and destroyed most of the island while shooting unstable clouds of hot gas to the surrounding area.

However, plenty of witnesses farther away did survive — and there were a lot of them. Some 100 miles away in North Jakarta, the noise still reached around 172 decibels. Violent tsunamis shook the Indian Ocean, and the waves even rocked boats in South Africa. Atmospheric pressure spikes reached as far as England, and a cloud of ash bathed an area of 300,000 square miles around the volcano in darkness. The global temperature even dropped, and didn’t return to normal until five years later.

Hunga Tonga-Hunga Ha’apai Eruption

The closest we’ve come to a repeat of Krakatoa was likely the Hunga Tonga-Hunga Ha'apai eruption near the Polynesian island of Tonga in January 2022. Sonic booms were felt as far north as Alaska, and researchers more than 6,000 miles away at Boise State University in Idaho recorded subterranean frequencies equivalent to about 100 decibels. The force, which was about half that of Krakatoa, sent a wave of pressure around the globe.

Fortunately, this blast wasn’t nearly as deadly, with three fatalities recorded compared to Krakatoa’s estimated 36,000. Still, it wreaked a lot of havoc. Tonga was largely cut off from the rest of the world for days, ash blanketed large swaths of the surrounding area, and tsunamis caused major damage along the coastlines. On one of the closer outlying islands, all the homes were destroyed. The volcano had created its own new island several years before; that was entirely obliterated, along with large chunks of two nearby islands.

Sperm Whales

Planet Earth is full of loud animals. Howler monkey cries can be as loud as gunshots, for example, and some species of bats emit high frequencies that could be harmful to us if they were low enough to hear. But nobody holds a candle to the sperm whale, whose clicks and calls have been measured as high as 230 decibels. That number drops significantly if the sound is traveling through air, but at 170 decibels, it’s still ear-shattering.

Scientists had thought for a long time that sperm whales were silent, but whalers had long told stories of what sounded like knocking on ships’ hulls when sperm whales were present. Once scientists listened to sperm whales with an underwater receiver, they thought the “muffled, smashing noise” was coming from inside the ship at first, before realizing they were picking up the atypical sounds of sperm whales, which don’t have the song-like quality of other species.

These Morse code-like clicks, used by sperm whales to communicate with one another, form an elaborate language, including phrases of clicks called codas. Different groups of whales even have different dialects within their codas. In addition to their communicative clicks, sperm whales also send out waves of sound at multiple frequencies as a form of echolocation while hunting their favorite food: giant squid.

Tsar Bomba

You’ll often see explosions compared to the force of a nuclear blast — but no blast was bigger than Tsar Bomba, aka Big Ivan, a Soviet thermonuclear bomb detonated as a test on a small island in the Arctic Ocean in 1961. It was at least 3,300 times more powerful than the United States bomb dropped on Hiroshima in 1945, although its potential capacity was twice that. The flash was seen more than 600 miles away, and monitors as far away as New Zealand recorded three rounds of pressure waves.

As for the sound itself: A cameraman recording the event described it as “a remote, indistinct and heavy blow, as if the Earth has been killed.” The blast is typically referred to in terms of its force rather than its decibel level, but 224 decibels is a common estimate.

Saturn V Rocket

It’s no secret that rocket launches are really, really loud, but the Saturn V rocket, launched in the 1960s and 1970s during the Apollo program, was notoriously noisy. In testing, it measured as high as 204 decibels, although NASA notes that it typically maxed out at 195 — still plenty noisy enough to be dangerous.

Legends have circulated about this noise, some of them myths. It didn’t melt the concrete underneath it or start grass fires a mile away. Still, launch viewers had to stand around 3.5 miles away from the pad for their own safety.

NASA’s new Space Launch System (SLS) rockets will be even louder and more powerful, but the launch pads will have built-in sound dampening capabilities, using around 450,000 gallons of water that will rush onto the pad at launch to protect both eardrums and the equipment itself.

The Tunguska Event

Asteroid impacts, like the 2013 Chelyabinsk Event, have created some of Earth’s biggest sounds, but the 1908 Tunguska Event in Siberia is perhaps the most legendary. Scientists believe that a space rock around 120 feet in diameter entered Earth’s atmosphere at about 33,500 miles per hour. After the resulting heat and pressure destroyed the rock itself, it became a fireball, releasing a destructive level of energy with no impact crater. Researchers were able to track ground zero from the pattern of the trees in the decimated forest around it; they fanned out radially away from the crash site until the very center, where trees stood upright, but entirely stripped of bark and branches.

One witness describes the impact’s sound as “a mighty crash… followed by a noise like stones falling from the sky, or of guns firing.” He had been working at a trading post 40 miles from the impact, and had been knocked out of his chair by a heat blast that made him feel as if his shirt was on fire. Later, scientists would estimate the sound of the blast at around 197 decibels.