Krakatoa Volcano Erupts

Date August 27, 1883

The eruption of Krakatoa was one of the most powerful and deadly volcanic eruptions in recorded history, initially killing more than thirty-six thousand people in the region with its main blast. The eruption’s aftereffects reached global proportions, as it triggered tsunamis, altered weather patterns and atmospheric conditions, and blurred and darkened skies.

Locale Krakatoa Island, Dutch East Indies (now Indonesia)

Key Figures

• Rogier Verbeek (1845-1926), Dutch colonial official who published a major study of the eruption in 1886

Summary of Event

A 60,000-year-old volcanic island, Krakatoa exploded on Monday, August 27, 1883. Before its cataclysmic disappearance, Krakatoa was a 15-square-mile island with abundant wildlife and plants, about midway in the Sunda Strait. The strait separates the much larger islands of Java and Sumatra and is a major gateway to the Indian Ocean. Krakatoa island was 22 miles (35 kilometers) from Java and 30 miles (50 kilometers) from Sumatra.

The three islands, as well as many others directly east, were part of the former Dutch East Indies. The Dutch colonial government occupied Krakatoa at different times and for different reasons. It was used as a lookout station, a small shipyard, a base for a small fishing fleet, and a prison for indigenous peoples. The island, however, was uninhabited when it erupted.

The eruption’s human tragedy occurred in the densely populated coastlines inside the Sunda Strait facing the volcano. Before the explosion, tens of thousands of people lived in small fishing villages and towns, Dutch-owned plantations, and small farms in the exposed areas. Virtually everyone in the blast zone thought that Krakatoa was a harmless silhouette of tropical green forest on the horizon, and it was relatively distant and had not erupted in more than two hundred years.

On May 20, Krakatoa’s magma chamber hurled its first fiery cloud of pyroclasts (burning particles of rock, ash, and cinders). The explosion was the start of the island’s great disappearing act, which would end dramatically on August 27. The May 20 eruption was large enough to destroy virtually all the island’s vegetation. Showers of pyroclasts from the blast fell on passing ships, but there were no injuries on board. The Sunda Strait’s Dutch, Chinese, and indigenous settlers were surprised, and some were even terrified, by the sound of the explosion, but they experienced only an annoying film of ash.

Just seven days after the eruption, a Dutch steamship company in Batavia (now Jakarta) loaded tourists on an excursion vessel that landed on the island. Aside from burning the soles of their shoes, the sightseers spent an uneventful afternoon on the still-fuming volcano. For the next three months, the volcano rumbled, spit out gas and steam, and provided delightful pyroclastic displays for people on Java and Sumatra and passers-by on ships. The last human being to stand on Krakatoa was a Dutch army captain sent there to begin mapping the altered island. Intent on returning, he left with a half-finished map on August 12.

The first of four larger convulsions began Sunday evening, August 26, 1883. The second and third explosions took place at around 5:30 a.m. and 7 a.m. on August 27. The same day, the sequence ended with the most violent explosion in recorded history at about 10 a.m. The final blast was especially powerful partly because earlier explosions tore fissures into the sides of the volcano. These ruptures allowed seawater to rapidly pour into the underground magma chamber. The mixture of superheated seawater and magma created a marked buildup of pressure inside. The mountain suddenly became like a giant pressure cooker. The flanks of the mountain gave way to the pent-up pressure by bursting outward and upward.

The energy released by the four explosions equaled the force of 100 million tons of dynamite. (The force of the Hiroshima nuclear bomb during World War II was about 20,000 tons of dynamite.) More than 6 cubic miles (25 cubic kilometers) of rock, ash, and pumice blew skyward. Furthermore, each of Krakatoa’s explosions generated one large and several small tsunamis (seismic sea waves), which occur after the spastic motions of an exploding island volcano or the jolts of an earthquake on the sea floor pass energy into the water. These waves move through deep water practically undetected, but as they approach a shoreline through more shallow water, they gain height rapidly.

The tsunamis washed over small islands and completely wiped out their populations before reaching Java and Sumatra’s coastline. Each wave’s arrival must have been terrifying. If victims had not drowned right away, then thrashing water and swirling tree trunks and other debris pummeled them to death. Krakatoa’s fourth and final eruption created by far the largest, most destructive wave, which reached heights up to 115 feet (35 meters) in some places. In comparison, Tambora, another Indonesian volcano, erupted in 1815 and killed ninety-two thousand people, during and after its main explosion. Krakatoa’s toll of more than thirty-six thousand deaths came directly from the volcano’s eruption. Tambora’s main blast killed about 12,000 people; post-eruption starvation and disease took the remaining lives.

Evidence of the volcano’s massive convulsion was obvious near and far. The volcano had disappeared, except for a small piece of its southern flank (now Rakata Island). The tsunamis destroyed 295 villages and killed more than 36,000 people in the Sunda Strait. A ship sailing west through the strait reported seeing bloated human corpses in groups of fifty to one hundred for two days. In the Indian Ocean, hundreds of miles from where the island once stood, ships navigated through acres of floating pumice (a porous lightweight volcanic rock). The skies as far east as Batavia—80 miles (130 kilometers) distant—were nearly pitch-black by midday on Monday, two hours after the largest explosion. Several hours later, a tsunami killed a woman while working in a rice paddy 2,000 miles (3,200 kilometers) away in Ceylon. She was probably the most distant casualty.

Twelve hours later, a tsunami of notable height—4 feet (1.2 meters)—struck the southeastern coast of Africa. Ocean currents washed pumice and the sun-bleached skeletons of victims onto the same coast more than one year after the eruption. Airborne shockwaves recorded on barographs traveled around Earth seven times and continued for fifteen days. Winds scattered volcanic aerosols—tiny particles of airborne dust and sulfuric acid—around the globe. The aerosols caused multihued and vermillion sunrises and sunsets for months. These atmospheric effects were reported from latitudes covering 70 percent of the globe, ranging from Reykjavik, Iceland, to Buenos Aires, Argentina.

In 1885-1886, Rogier Verbeek, a Dutch colonial official in Batavia, published a detailed study of the eruption called Krakatau. The Royal Society (Great Britain’s national academy of science) collected reports of the eruption’s effects from more than eight hundred locations around the world, presenting its own report in 1888.

Significance

The Krakatoa eruption, infamous for its physical effects, remains the deadliest volcanic explosion in recorded history. The blast caused an immense sonic reverberation, as the sound of its main blast traveled 2,900 miles (4,660 kilometers). No other natural sound is known to have traveled so far. Additionally, modern tree-ring analyses suggest that Krakatoa’s aerosols blocked enough solar energy from reaching Earth’s surface to reduce average global temperatures to below normal. The average solar radiation in Europe decreased 10 percent and crop yields decreased as well.

Krakatoa’s eruption stirred artistic passions as well as scientific interest. William Ascroft, an English watercolor artist, became famous for his prolific renderings of Krakatoa sunsets. Edvard Munch, a Norwegian artist, was reportedly inspired to paint his well-known work The Scream after hearing of the devastation. Other paintings, as well as poems, children’s stories, and Hollywood films, also immortalized Krakatoa.

Historian Simon Winchester pointed out what is perhaps Krakatoa’s major significance: It occurred during a science-conscious Victorian age, when Europeans were beginning to think about ecological links among people and place. Winchester noted that Krakatoa’s eruption, “an event that intersected so much and affected so many, seemed all of a sudden to be an example of this newly recognized phenomenon,” that is, the essential connections between Earth’s inhabitants and Earth itself. Krakatoa’s eruption, devastating as it was, led to increased understandings of Earth’s ecosystem.

Bibliography

Botkin, Daniel B., ed. Forces of Change: A New View of Nature, Washington, D.C.: National Geographic Society, 2000. Prominent scientists offer perspectives on global change and the processes that shape it, including the role of volcanic eruptions.

Francis, Peter. Volcanoes: A Planetary Perspective. New York: Oxford University Press, 1993. Presents a global history of volcanoes and volcanic eruptions.

Simkin, Tom, and Richard S. Fiske. Krakatoa, 1883: The Volcanic Eruption and Its Effects. Washington, D.C.: Smithsonian Institution Press, 1983. A technical description of the eruption that incorporates the theory of plate tectonics to explain the blasts.

Simmons, G. J., ed. The Eruption of Krakatoa, and Subsequent Phenomena. Report of the Krakatoa Committee of the Royal Society. London: Trüber, 1888. Reprint. La Jolla, Calif.: University of California, Scripps Institution of Oceanography, 1952. Contains maps, tidal graphs, eyewitness accounts, and factual observations of the eruption and its aftermath.

Thornton, Ian W. B. Krakatau: The Destruction and Reassembly of an Island Ecosystem. Cambridge, Mass.: Harvard University Press, 1996. An award-winning work that explores the ecological effects of the eruption. Includes maps, illustrations, biographical references, and an index.

Verbeek, Rogier. Krakatau. 2 vols. Batavia: Government Printing Office, 1885. Includes original diagrams, tables, and maps documenting the eruption’s timing and the distribution of its effects. In Dutch.

Winchester, Simon. Krakatoa—The Day the World Exploded: August 27, 1883. New York: HarperCollins, 2003. Examines Krakatoa’s geological, geographical, and sociological settings. Includes the chapters “The Moments When the Mountain Moved” and “The Unchaining of the Gates of Hell.” Illustrations, maps, bibliographical references, and index.