On August 27, 1883, at 10:02 in the morning, Krakatoa, a small uninhabited isle between Java and Sumatra, unleashed a cataclysm that reshaped the region. The eruption wiped the island from the map and sent tsunamis racing across the Indian Ocean, with waves towering up to 46 meters and smashing coastlines as far away as South Africa. It remains the most intensely recorded sound in human history.
Krakatoa stood 838 meters above sea level and had not erupted since 1680 before its dramatic reawakening in 1883. The blast released energy comparable to a 200-megaton nuclear device, vastly exceeding the power of the Hiroshima explosion. The event left a long footprint on both people and ecosystems, a fact noted by the Natural History Museum in assessments of its global reach.
In terms of fatalities, Krakatoa ranks as the second deadliest eruption in modern times, with around 36,000 lives lost. It trails the Tambora eruption of 1815, also in Indonesia, which claimed tens of thousands more.
These moments became iconic visuals of chaos—the explosion was so immense that reports from that era describe the fireball, shockwaves, and sound being recorded over vast distances. The blast generated a sustained pressure pulse that many listeners interpreted as a thunderous roar, heard many thousands of miles away.
The eruption produced surface-level sound that traveled through the atmosphere and entered human perception at unusual distances. Accounts indicate that the blast could be heard from the Andaman and Nicobar Islands in India, over two thousand kilometers away, and even farther—more than three thousand kilometers—across New Guinea and Australia. Some listeners reported hearing it on islands in the Indian Ocean about five thousand kilometers from Krakatoa.
Near the source, instruments recorded remarkable numbers. A barometer at a gas works about 160 kilometers away recorded a sound level of 172 decibels on the day of the explosion—a figure so intense it would rupture ear drums at close range and well beyond, since 120 decibels already produce discomfort and 130 decibels can feel painful. Each ten-decibel increase equates to a roughly twofold increase in perceived loudness.
The same narrative of distance and impact appears in photographs and captions from the era. An eyewitness account from a captain of a British vessel described shattered eardrums among his crew and darkened skies as the noise rolled outward across the sea. He remarked that the day felt like an omen, a moment that would live in memory for generations.
The shock wave from Krakatoa did not quiet with distance. It circled the globe multiple times, gradually losing intensity as it moved outward, yet remaining audible for a long time. Research from acoustic scientists shows that the wave could still be perceived as a distant crack, like a gunshot, thousands of kilometers away before fading completely.
In the broader atmospheric record, the pressure wave produced a global phenomenon. The earth experienced three full circumnavigations, with shock waves colliding across continents, creating secondary pressure peaks. The great airwave circulated for a period, eventually dropping below the threshold of human hearing and marking the end of the loudest sound in recorded history.
More recently, researchers point to the Tongan eruption of January 2022 as the next loudest event on record. Sounds were reported across Alaska, roughly 6,200 kilometers away, while the volume of the Tonga blast drove sound waves around the planet at speeds surpassing 1,100 kilometers per hour and reaching altitudes high enough to traverse the edge of space.
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Environmental authorities emphasize that the Krakatoa episode offers a stark reminder of the power of natural processes to impact air, water, and living systems across vast distances. The event remains a focal point for studies in geology, acoustics, and disaster preparedness, continuing to inform how scientists understand volcanoes, atmospheric propagation of sound, and the long shadows cast by such forces across human history.