Volcanic Eruptions (Indonesia) #2

Case Study 1: Tambora, 1815 Volcanic Eruption in Indonesia

Tambora is located on Sumbawa Island, on the eastern end of the Indonesian archipelago. The volcano, which began rumbling on April 5, lasted for 2 hours. Over the next three or four days, 50 km³ of magma was expelled in the form of ash fall and pumice-rich pyroclastic flowed. The eruption was the largest ever recorded and its effects were noted throughout the world. There had been no signs of volcanic activity there for thousands of years prior to the 1815 eruption. On April 10, the first of a series of eruptions that month sent ash 20 miles into the atmosphere, covering the island with ash to a height of 1.5 meters. The magnitude was seven on the Volcanic Explosivity Index (VEI)1 scale.

On the island of Sumbawa, it is estimated that 10,000 people were killed by pyroclastic flows, 32,000 by starvation and another 10,000 due to disease and hunger.
The 1815 Tambora eruption is the largest observed eruption in recorded history. The explosion was heard 2,600 kilometers away, and ash fell at least 1,300 kilometers away. Pitch darkness was observed as far away as 600 kilometers from the mountain summit for up to two days. The eruption expelled a total of approximately 140 gigatonnes of magma and generating an ash cloud that reached a height of up to 43 km. More than 95 percent of the ejected mass was erupted as pyroclastic flows that spread at least 20 kilometers from the summit, with 40 percent of this ending up as ash fallout. Floating pumice rafts and charred tree trunks hindered shipping in the area for three years after the eruption.

The Volcanic Explosivity Index (VEI) was devised by Chris Newhall of the U.S. Geological Survey and Steve Self at the University of Hawaii in 1982 to provide a relative measure of the explosiveness of volcanic eruptions