page_title: 1883 eruption of Krakatoa
section_title: Geographic effects
hierarchical_section_title: 1883 eruption of Krakatoa / Effects / Geographic effects
caption_attribution_description: English: Evolution map in English of the Krakatoa's archipelago (Indonesia), between 1880 and 2005. The main eruption was in 1883. Español: Mapa, en inglés, de la evolución de el archipiélago Krakatoa (Indonesia), entre 1880 y 2005. La erupción principal fué en 1883. Français&#160;: Carte de l'évolution de l'archipel du Krakatoa (Indonésie), entre 1880 et 2005. L'éruption principale date de 1883. 日本語: クラカタウ群島（インドネシア）の1880年～2005年にかけての変遷地図。大噴火は1883年。（英語）
context_page_description: The 1883 eruption of Krakatoa in the Sunda Strait began on the afternoon of Sunday, 26 August 1883—with origins as early as that May—and peaked on the late morning of Monday, 27 August 1883, when over 70% of the island of Krakatoa and its surrounding archipelago were destroyed as it collapsed into a caldera.
  The eruption was one of the deadliest and most destructive volcanic events in recorded history and explosions were so violent that they were heard 3,110 kilometres away in Perth, Western Australia, and Rodrigues near Mauritius, 4,800 kilometres away. At least 36,417 deaths are attributed to the eruption and the tsunamis it created.
  Significant additional effects were also felt around the world in the days and weeks after the volcano's eruption. Additional seismic activity continued until February 1884; reports of seismic activity after October 1883 were later dismissed by Rogier Verbeek's investigation into the eruption.
context_section_description: In the aftermath of the eruption, it was found that Krakatoa had almost entirely disappeared, except for the southern third. The Rakata cone was cut off along a vertical cliff, leaving behind a 250-metre (820 ft) cliff. Of the northern two-thirds of the island, only a rocky islet named Bootsmansrots ('Bosun's Rock'), a fragment of Danan, was left; Poolsche Hoed had totally disappeared.
  The huge amount of material deposited by the volcano drastically altered the surrounding ocean floor. It is estimated that as much as 18–21 km³ (4.3–5.0 cu mi) of ignimbrite were deposited over 1,100,000 km² (420,000 sq mi), largely filling the 30–40 m (98–131 ft) deep basin around the mountain. The land masses of Verlaten and Lang islands were increased, as was the western part of the remnant of Rakata. Much of this gained material quickly eroded away, but volcanic ash continues to be a significant part of the geological composition of these islands. The basin was 100 m (330 ft) deep before the eruption, and 200–300 m (660–980 ft) after.
  Two nearby sandbanks (called Steers and Calmeyer after the two naval officers who investigated them) were built up into islands by ashfall, but the sea later washed them away. Seawater on hot volcanic deposits on Steers and Calmeyer had caused steam to rise, which some mistook for a continued eruption.
caption: Evolution of the islands around Krakatoa