1883 Krakatau eruption

Krakatau (often called Krakatoa in English-language sources) is a volcanic island complex in the Sunda Strait between Java and Sumatra, in present-day Indonesia. The 1883 eruption followed a period of relative quiet. The Smithsonian Global Volcanism Program records the eruptive episode as beginning on 20 May; contemporary observers in the region documented ash, columns of vapor and increasingly conspicuous explosions over the following months. The changing activity attracted ships and scientific attention before the catastrophic climax.

The most destructive phase occurred on 26 and 27 August 1883. Repeated powerful explosions culminated in the collapse of much of the island’s volcanic structure and the formation of a large caldera. The Global Volcanism Program classifies the event as VEI 6, on the Volcanic Explosivity Index. The eruption sent ash and other volcanic material high into the atmosphere and generated flows that crossed the surrounding water. Krakatau’s pre-eruption cones Danan and Perbuwatan were destroyed; only remnants of the older island remained above sea level.

Tsunamis struck nearby coastlines in the Sunda Strait, devastating settlements on Java and Sumatra. Historical accounts commonly place the total death toll at about 36,000, with the great majority attributed to the tsunamis rather than the direct effects of ash or volcanic flows. Volcanic material moving into the sea and collapse of the island complex are both relevant to tsunami generation, but the precise contribution of each process is not fully resolved. The event became an important case study in the severe tsunami hazards that can accompany island volcanoes.

Ash and sulfur-bearing particles from the eruption spread through the atmosphere. They affected the appearance of sunlight and moonlight in distant regions and contributed to temporary global cooling. The eruption’s effects were recorded by instruments and observers far from Indonesia, making it an unusually well-documented event for its era. Estimates of particular atmospheric and temperature effects vary by source and method, so popular descriptions of the eruption’s global influence should not be read as measurements of identical precision.

The 1883 event did not end volcanic activity at Krakatau. Submarine eruptions began within the caldera in late 1927. An ephemeral island appeared above sea level in 1929, and Anak Krakatau (Indonesian for “Child of Krakatau”) later became a permanent island as eruptions continued. A separate collapse and tsunami occurred at Anak Krakatau in 2018. These later events are part of the same volcanic complex but are not part of the 1883 eruption; distinguishing them helps avoid treating Krakatau as a single, unchanged island.