Krakatoa Eruption

In late August 1883, the volcanic island of Krakatoa in the Sunda Strait, between Java and Sumatra in what was then the Dutch East Indies, exploded in one of the most violent eruptions in recorded history. The blast generated enormous tsunamis that killed tens of thousands of people along nearby coasts, and its effects were felt around the world. It was also among the first major disasters to be reported globally within days, thanks to the telegraph and undersea cables.

Krakatoa sits on the volcanic arc formed where the Indo-Australian Plate is subducted beneath the Sunda Plate. The island had a history of large eruptions, and local accounts and later historical sources suggest a major earlier event, though its details are debated. In May 1883, the volcano began venting ash and steam, and activity continued through the summer. Ships reported ash clouds, and residents on nearby shores felt tremors and heard detonations, but few anticipated the scale of what followed.

The climax came on 26 and 27 August. Explosions intensified through the 26th, and on the morning of the 27th a series of massive blasts destroyed much of the island. The loudest is often said to have been heard thousands of kilometres away, including on Rodrigues Island in the western Indian Ocean and in parts of Australia, making it one of the loudest sounds in recorded history. The collapse of the volcano and pyroclastic flows entering the sea helped generate tsunamis, some of which reached heights of tens of metres on nearby shorelines. Coastal towns and villages in Java and Sumatra were swept away.

The official Dutch colonial death toll was about 36,000, and most of those deaths were caused by the waves rather than by ash or falling debris. Some modern researchers think the true figure may have been higher, since records from the region were incomplete. Pressure waves from the explosion traveled around the globe several times and were recorded by barometers far from Java.

The eruption also altered the atmosphere. Fine ash and sulfur compounds injected into the stratosphere scattered sunlight, producing strikingly vivid red sunsets and twilight glows in many parts of the world for months. Global average temperatures dropped slightly for a few years. Some historians have suggested that the unusual skies influenced artists and writers, and the sky in Edvard Munch's The Scream is sometimes linked to them, though this is debated.

Krakatoa's destruction left a submerged caldera. In 1927, a new volcanic cone, Anak Krakatau ("Child of Krakatoa"), emerged from the sea there. Its own collapse in December 2018 triggered another deadly tsunami, a reminder that the hazard persists.