In August 26-27, 1883, a small island in the Indian Ocean obliterated itself in one the most notorious volcanic eruptions in history. Krakatau (often spelled Krakatoa) erupted with such violence that two-thirds of the island, about 23 square kilometers, sank into the Sunda Strait. The explosions heard in the 1883 eruption remain the loudest noise on human record. The sound was heard across the Indian Ocean, as far away as Rodriguez Island, 4,653 kilometers to the west, and Australia, 3,450 kilometers to the east. The massive eruption also generated a series of tsunamis, which produced waves as high as 30 meters tall.
During its final cataclysmic eruption Krakatau, which had been an island of about 30 square kilometers (12 square miles), nearly vanished. A total of 25 cubic kilometers (6 cubic miles) of material, including both new magma and bits of the old island, were blown into the stratosphere, the eruption column reaching more than 30 kilometers (20 miles) high.
The huge waves created when Krakatau erupted were responsible for most of the 36,000 deaths associated with the event. While satellite imagery of Krakatau’s 1883 eruption is obviously not available, we do have images of Anak Krakatau to share.
On 1927, About 50 years after Krakatau destroyed itself, a new island appeared from the sea in about the same place. Called Anak Krakatau, meaning “Child of Krakatau” this young volcano now stands about 500 meters (1,500 feet) above the waves. Since then, Anak Krakatau has been the site of frequent eruptions. This image of Anak Krakatau was taken by the Ikonos satellite on June 11, 2005. The volcano has been the site of frequent eruptions since 1927.
Like most of the approximately 130 active volcanoes in Indonesia, Krakatau was formed along the Sunda Arc, a 3,000-kilometer-long curve where the Australia Plate sinks beneath the Eurasia Plate. Where these two sections of the Earth’s crust meet, earthquakes and volcanic eruptions are common. Krakatau and the Sunda Strait sit at the hinge of the curve between Sumatra and Java, making this a region particularly prone to geologic activity.