On this day in 1883, between the early morning and midday, four great explosions destroyed most of the island of Krakatoa in the Sunda Strait. The third, at about two minutes past ten, is still counted the loudest sound in recorded history; it was heard thousands of kilometres away, and the pressure wave it sent out was picked up by barographs around the world as the pulse travelled and returned, several times over, in the days that followed.
The deaths came mostly from the sea. As the island collapsed into its caldera, the water displaced was thrown outward as a series of waves that struck the low coasts of Java and Sumatra within the hour. Anyer, Merak and Telok Betong were gone by evening. Ash fell for days across the strait and darkened the sky. The commonly cited figure is about 36,000 people killed, and the true number is not known.
What we know of the timing was largely reconstructed afterwards from instruments and paper: tide gauges in distant ports that recorded small oscillations at calculable hours, barograph traces, and the logs of ships that were in or near the strait and wrote down what they saw and when. A committee of the Royal Society spent years gathering those accounts into a single report. The lithograph below shows the ash column above the island.
Thirty-six thousand people, on two coastlines, in one morning.
One of the fullest hour-by-hour accounts came from the barque Charles Bal, working close inshore through that morning, whose master kept writing down the times of what he heard and saw. Historians still lean on that log, and on the men who kept it while it was happening.
The sound reached Rodrigues in the Indian Ocean, nearly 4,800 kilometres away, where it was taken for distant gunfire. The dust stayed high in the air well into the following year, and observers across the world recorded discoloured skies and strange sunsets long after.