A series of volcanic explosions sunk two-thirds of the island of Krakatoa. Giant tsunamis and toxic gases brought mass death and destruction to Indonesia.
Krakatoa, also known as Krakatau, is a volcanic island located in the Sunda Strait between the islands of Sumatra and Java in Indonesia. This island is adjacent to two other islands, Verlaten and Lang.
These three islands are remnants of the original island Ancient Krakatoa. The volcanic explosion in 1883 caused most of Krakatoa to collapse into the sea and these islands were the land masses that remained above sea level.
A fourth island, named Anak Krakatau (meaning ‘child of Krakatoa”) was formed after a volcanic eruption in 1927. It sits over one of the three active volcanic vents that were once part of Ancient Krakatoa and continues to have minor eruptions to this day.
Events Leading up to the Explosion of Krakatoa
The earliest signs of activity were detected by commercial trading ships who reported an eight-mile plume of smoke in late May, 1883. This was a result of minor eruptions from the Perboewetan volcano on the island of Krakatoa.
As the months went by, there was an increase in ash fallout and chunks of pumice were found on the islands in the area. As these eruptions were occurring, the caldera on Perboewetan was widening and more pressure was building underwater.
The first sizable blast of Krakatoa occurred in the early afternoon on August 26th, 1883. The volcano spewed a 15-mile high column of dark volcanic gas and it generated a shockwave which was felt in the neighbouring islands of Sumatra and Java. More explosions occurred which increased in intensity and sent the gas plume higher into the atmosphere.
Volcanic material started to spill down the flanks of the volcano. The effects of the blasts generated a series of tsunamis which destroyed coastal villages on several islands in Indonesia.
The Explosion of Krakatoa August 27th, 1883
The first of four catastrophic explosions occurred at 5:30am on August 27th, 1883. An increasingly thick blanket of pumice and ash enveloped the neighbouring islands. Tsunamis of 100 feet high caused more damage along shorelines.
The second blast occurred at 6:44am and it repeated the effects of the first blast. The third blast at 10:20am was the most intense of the four. Two-thirds of Krakatoa sunk into the caldera which was sitting at 750 feet below sea level. The last blast at 10:52am was not as intense but it perpetuated the damage.
The Effects of the Explosion of Krakatoa
A research paper published by The Department of Physical Geology at Earlham College, reported; “In total, 23 square kilometers of the island fell into the 6km wide caldera. The ground shook in the wake of the blast which was heard over 4500km and was estimated to be equal to the detonation of over 21,000 atomic bombs.”
Pyroclastic flows spread over the Sunda Strait and affected the coastal areas of Sumatra where thousands of residents were killed immediately by the blast of hot gases.
Powerful tsunamis hit the shores of the Indian Ocean, similar to the killer tsunami that occurred on December 26th, 2004 when a very strong earthquake ruptured the ocean floor near the west coast of Sumatra, Indonesia.
According to the Department of Geological Sciences, San Diego State University, “These tsunamis stripped away all vegetation, washed ~30,000 people out to sea, and destroyed all signs of human occupation.”
The final death toll was estimated at 36,417.
Scientists continue to monitor the volcanic activity on Anak Krakatau after a small eruption occurred in 2007
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