At about 10 a.m. on 27 August 1883, the volcanic island of Krakatoa, in the Sunda Strait between Java and Sumatra, tore itself apart in one of the most violent explosions in recorded history. The sound was heard nearly 3,000 miles away: on Rodrigues Island in the Indian Ocean, some 4,800 kilometres distant, the local police chief reported what he took to be the distant gunfire of ships. In Australia, people heard booming and assumed artillery or blasting. Forty miles from the volcano, the concussion ruptured the eardrums of sailors aboard the British ship Norham Castle, whose captain wrote in his log that he thought the Day of Judgement had come. It is generally reckoned the loudest sound of the modern era. The atmospheric pressure wave it launched was recorded on barographs around the world circling the globe multiple times over the following days — roughly seven passages in all.
Krakatoa had given warning. The volcano, part of the Dutch East Indies (modern Indonesia), had been quiet for around two centuries before it began erupting in May 1883. Through the summer, ash columns and rumblings became a regional spectacle; excursion boats even took sightseers out for a look. Then, on the afternoon of 26 August, the eruption escalated savagely, and through that night and the following morning came a series of cataclysmic explosions, of which the third, mid-morning on the 27th, was the monster. When the air cleared, most of the island was simply gone — roughly two-thirds of it had vanished, collapsed into a caldera beneath the sea. Volcanologists rate the eruption a 6 on the Volcanic Explosivity Index.
The killer was the sea
Almost none of the official death toll of 36,417 came from lava — Krakatoa was uninhabited. The killer was water. The collapse and the explosions drove tsunamis through the narrow Sunda Strait that reached heights of 30 metres or more, obliterating some 165 coastal towns and villages on Java and Sumatra. The port towns of Anjer and Merak were effectively wiped from the map. In one of the disaster's most surreal episodes, the Dutch government steamship Berouw was picked up by a wave and deposited well inland up a river valley on Sumatra, killing all 28 of her crew. Pumice rafts — floating fields of frothy volcanic rock, some carrying human remains — drifted across the Indian Ocean for months, washing up as far away as Africa.
Krakatoa was also arguably the first global media catastrophe. The world had recently been wired together by submarine telegraph cables, and news from the Javan port of Batavia (now Jakarta) reached London and New York within hours via Reuters. People on every continent read about the eruption while its atmospheric effects were still arriving overhead — a genuinely new experience for humanity, and one reason Krakatoa lodged so deeply in the global imagination.
The year the sky changed
The finest ash and sulphurous gas blasted into the stratosphere spread around the planet and stayed there for years, with strange and beautiful consequences. Sunsets worldwide turned lurid crimson and green; in November 1883, fire engines were reportedly called out in New York State to chase a blaze that turned out to be the twilight sky. Observers recorded a blue or green tinge to the sun and moon in some regions, and a halo effect around the sun known as a Bishop's ring. Some art historians have speculated that the blood-red sky in Edvard Munch's The Scream echoes the Krakatoa twilights he would have seen over Oslo in the 1880s, though the claim remains debated. The volcanic veil also filtered sunlight enough to nudge global temperatures measurably downward for several years — a natural demonstration of the "volcanic winter" effect scientists still study, and the Dutch scientist Rogier Verbeek's exhaustive report on the eruption helped found modern volcanology.
The volcano itself was not finished. In 1927, fishermen noticed steam and debris boiling up from the sea over the old caldera, and a new cone soon breached the surface. It was named Anak Krakatau — "Child of Krakatoa" — and it has been building and erupting intermittently ever since; in December 2018 a flank collapse sent another deadly tsunami into the Sunda Strait, a grim reminder that the story is not over. One final quiz-friendly footnote: the 1969 Hollywood disaster film about the eruption was titled Krakatoa, East of Java. Krakatoa lies west of Java.
Quiz nuggets
- Krakatoa's climactic explosion on 27 August 1883 was heard nearly 3,000 miles away, on Rodrigues Island near Mauritius.
- The official death toll was 36,417, most killed by tsunamis rather than the eruption itself.
- The pressure wave was recorded circling the globe about seven times on barographs worldwide.
- Anak Krakatau, "Child of Krakatoa," emerged from the sea over the old caldera in 1927.
- The 1969 film Krakatoa, East of Java got its geography wrong — the volcano is west of Java.