The Loudest Sound in Recorded History: Krakatoa 1883

A volcano is heard almost three thousand miles away. Its waves climb up to forty-two metres. Its news races round the world by telegraph. Its dust turns sunsets blood red. Some say it inspired the painting The Scream. This is Krakatoa. Here's how it happened.

Start with a strait. The Sunda Strait, between the islands of Java and Sumatra, in what was then the Dutch East Indies and is now Indonesia. In the middle sits a small volcanic island. Krakatoa. Nobody is worried about it. It has slept for nearly two centuries, since a modest eruption in 1680, and it is covered in green forest. Then, on Sunday the twentieth of May 1883, booming sounds like artillery are heard in Batavia, today's Jakarta, nearly a hundred miles away. Doors and windows rattle for hours. Within a week, an excursion party sails out from Batavia to look. They find the island dusted white, like snow, with explosions every five to ten minutes. It is, briefly, a tourist attraction. Over the summer, the residents of Batavia, who are used to volcanoes, stop paying much attention. That turns out to be a mistake. On Sunday the twenty-sixth of August, around two in the afternoon, a steamer arriving at the port of Anjer hears the first explosion that matters.

Around one o'clock that afternoon, the eruption enters its final phase. By two, a black cloud of ash stands about twenty-seven kilometres high, some seventeen miles. At half past five, a heavy detonation is heard. Soon afterwards, the first large wave reaches the Java shore at Tyringin, twenty-four miles away, and wrecks houses near the sea. Another hits Telok Betong, on the Sumatran side. Out at sea, Captain Wooldridge of the ship Sir Robert Sale watches the volcano at sunset. He sees a cloud like an immense pine tree, its trunk and branches formed of volcanic lightning. In the harbour at Telok Betong, a Dutch government steamer, the Berouw, lies at anchor by the pier. Nothing suggests what is about to happen to her. All night, the sea is rough and the sky flickers. The volcano is not done. It has four great explosions still to come, and the third is the one the world will remember.

Monday, the twenty-seventh of August. The first great explosion comes at half past five in the morning. Within the hour, a wave sweeps away most of the low-lying town of Anjer. The second explosion comes at 6.44. At half past seven, a second wave finishes the job at Anjer. The third explosion, at 10.02, is the largest. A fourth follows at 10.52. Along the coasts, the water climbs. At Telok Betong, it comes within six feet of the top of the hill where the Dutch Resident, the local administrator, has his house. That is a rise of about seventy-two feet. At the village of Katimbang, the Dutch mining engineer Rogier Verbeek records eighty feet. At Merak, the water leaves its mark at a hundred and fifteen feet. Modern studies give a maximum run-up of up to forty-two metres, about a hundred and thirty-eight feet, at Merak, where the shape of the bay funnelled the wave. These are measurements from different shores, and the sea does not behave the same everywhere. And the Berouw, the steamer at the pier at Telok Betong, is lifted by the sea and carried up the valley, almost two miles inland. She is left about eighty feet above sea level. A ship, in a forest. Then the count. The official Dutch figure is 36,417 people, and modern studies say at least thirty-six thousand. The Royal Society's report, a few years later, gives 36,380, of whom thirty-seven were Europeans. Most were killed by the waves, in some hundred and sixty-five villages along the coasts of Java and Sumatra. Some died in a surge of hot ash on the Sumatran side. There is no joke to make here, so we won't. But those who survived, and those who wrote it down, left us something extraordinary. Because the third explosion was not just seen. It was heard.

On the island of Rodrigues, in the Indian Ocean, nearly three thousand miles away, about forty-eight hundred kilometres, the chief officer of police, James Wallis, gives an account. Through the night, he says, reports were heard from the eastward, quote, 'like the distant roars of heavy guns.' They continued at intervals until three the next afternoon. On Diego Garcia, more than two thousand miles from the volcano, people take the sounds for a ship in distress, firing guns. The Royal Society later reckons the sounds were heard over about one-thirteenth of the Earth's surface. Closer in, at Batavia, a hundred miles away, the blast bursts windows and cracks walls. A gasometer leaps out of its well. Nobody measured the volume at the time. Later estimates vary, and they are reconstructed from barometers. It is often called the loudest sound in recorded history. But the blast also did something quieter. It pushed the whole atmosphere. A pulse of air pressure spread out across the planet at roughly seven hundred miles an hour, close to the speed of sound. Barometers at observatories around the world recorded it. It went all the way round the Earth, bounced back from the opposite side, and came again. Many stations logged seven passages of the wave. That is more than three laps of the planet. A volcano rang the atmosphere like a bell. But the sound was not the only thing travelling that week. The news was, too.

In 1883, something exists that did not exist when Tambora erupted, sixty-eight years earlier: a telegraph cable under the sea. From Batavia to Singapore, and from there, as the Royal Society's report puts it, to every part of the civilised world. In about a day, the story has gone round the globe. When Tambora went off in 1815, the best-known account was published two years later. Here, it is breakfast-table news. It is, to be fair, not very accurate news. The same report admits that the first dispatches were quote 'quite misleading and altogether unworthy of credence'. Which is hardly surprising. The survivors were in darkness, in the middle of a flood. Even so, this is among the first disasters the whole world follows almost as it happens. There is no record of anyone refreshing the page. But the real broadcast has not arrived yet. And it comes from the sky.

The explosion has thrown dust and gas far into the upper atmosphere. Within days, the sky changes colour. Observers in the tropics report blue and green suns. Then, from late November, the strange twilights reach Europe and North America. On the twenty-sixth of November 1883, a London artist, William Ascroft, sits on the bank of the Thames and sketches the sky in crayon. The Royal Society prints his drawings as colour plates in its report. The next day, in the United States, the glow is so bright that, in places like Poughkeepsie, New York, fire engines are called out in the morning for a fire that is only the sky. Meanwhile the dust is also dimming the sun. Estimates of the cooling vary, but the Northern Hemisphere seems to have cooled by a few tenths of a degree, about 0.3 degrees Celsius, for a few years. That is a smaller effect than Tambora's, and harder to measure. Observers are still sketching odd skies in 1885. And one of those skies may be the most famous in art. Maybe.

Now to Norway. The painter Edvard Munch later writes about a walk at sunset. 'All at once,' he says, 'the sky became blood red.' And he felt, in his words, a great, unending scream piercing through nature. His painting, The Scream, dates from 1893. In 2003, a team from Texas State University, Donald Olson, Russell Doescher and Marilynn Olson, proposed that the sky he saw was Krakatoa's. They placed Munch on Ekeberg hill, above Oslo, then called Christiania, looking south-west. They argued the walk took place between late November 1883 and mid-February 1884, when the glows were visible in Norway. This is a hypothesis. Art historians have dated the experience to autumn 1891, or to summer 1886. And other researchers have since proposed rare mother-of-pearl clouds instead. So did Krakatoa paint The Scream? Perhaps. What we can say is that the sky was real, and the whole world looked up at it. Now for the count. And for what grew back.

Back to the count. Nobody knows it exactly. The Dutch and Royal Society figures differ by a few dozen, and higher figures circulate, but none we found has a credible source. The Royal Society's report itself is a monument to an unusual idea: that the whole world should write in about what it saw. In 1888, a committee of the Royal Society, edited by G. J. Symons, published its findings: ships' logs, barograph traces, and letters about the sky. For months, the strait is choked with floating pumice, so thick in places that no ship can force its way through. As for the island, about two-thirds of it had disappeared. And then, on the twenty-ninth of December 1927, a new volcano rose from the sea in the middle of the old crater. It was named Anak Krakatau, the child of Krakatoa. By 1930 it stayed above the waves. It grew about seven to nine metres a year. In December 2018, part of it collapsed into the sea, and the tsunami that followed killed at least 437 people on the coasts of the same strait. It is still active. Krakatoa was not the last volcano to make the news. But that is another story. First, remember how this one began. A volcano is heard almost three thousand miles away.