How Far Away Was the 1883 Krakatoa Explosion Heard?

The Short Answer

On August 27, 1883, the final explosion of Krakatoa was heard nearly 3,000 miles away on Rodrigues Island — and the pressure pulse it created circled the entire planet for five days, making it one of the loudest and most far-reaching events in recorded history.

What Happened on August 27, 1883

Krakatoa had been rumbling for months, but the morning of August 27 was different. A series of catastrophic blasts — the largest arriving just after 10 a.m. local time — tore the island apart. The leading explanation for the violence: seawater had infiltrated the magma chamber through cracks opened by earlier eruptions, triggering a chain of superheated steam explosions that rapidly escalated beyond anything the weakened island could contain.

With its magma chamber suddenly emptied, the island had nothing left to support itself. Most of it collapsed inward in a caldera collapse — a geological implosion that triggered tsunamis reaching nearly 100 feet in height. Those waves devastated coastal towns across Java and Sumatra, killing an estimated 36,000 people.

Heard 3,000 Miles Away

Officials on Rodrigues Island, a small British territory in the Indian Ocean, logged what they heard as distant cannon fire. There were no cannons. What they recorded was a sound wave that had crossed roughly 3,000 miles of open ocean without losing enough energy to fall below human hearing. Accounts of unusual booming sounds came from locations across the Indian Ocean basin, the Australian coast, and beyond — the eruption is widely cited among scientists as the loudest sound in modern recorded history.

The Pressure Pulse That Circled the Globe

A barograph at Batavia (now Jakarta), about 100 miles from Krakatoa, captured the scale of the blast in precise mechanical terms: the needle spiked more than 2.5 inches of mercury — so far it went off the instrument’s scale. That pressure pulse then radiated outward at roughly 675 miles per hour.

Because barographs — drums of paper continuously recording atmospheric pressure — were already running at weather stations in approximately 50 cities worldwide, scientists had an unprecedented dataset. Station after station recorded the pulse arriving on schedule, like clockwork. At a single station, observers counted it passing up to seven times over five days as it bounced back and forth across the globe.

Ash That Painted the Sky

The eruption blasted ash and sulfur dioxide into the stratosphere. For months afterward, the upper atmosphere scattered sunlight in ways that turned sunsets and sunrises vivid red, orange, and purple across the entire planet. Some art historians believe the Norwegian painter Edvard Munch witnessed those unusual skies over Norway in the winter of 1883–84, and that the blood-red sky he later depicted in The Scream (painted in 1893) was a direct memory of that atmospheric afterglow.

The Sunda Strait After the Eruption

The explosion buried the Sunda Strait under floating mats of pumice so dense they blocked shipping lanes. Pumice from Krakatoa was still washing ashore on the coast of East Africa nearly a year after the eruption — a slow-motion reminder of the blast’s scale carried by ocean currents halfway around the world.

Anak Krakatau: The Child of Krakatoa

Forty-four years after Krakatoa destroyed itself, a new volcanic island broke the surface of the sea from within the same collapsed caldera. Indonesians named it Anak Krakatau — Child of Krakatoa. It remains active today, a visible sign that the geological forces that created the 1883 disaster are still very much at work beneath the Sunda Strait.