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The Tambora Volcanic Eruption, 1815
The island is part of a very active volcanic arc, which is part of the Ring of Fire around the Pacific Ocean.
Before the explosion, Tambora stood over 13000 ft (4000m) high. Starting in 1812, 3 years before the huge eruption, the volcano started spewing steam and ash and creating small tremors in the Earth. What people didn't know was what was coming next...
On the 5th of April, 1815, after lying quiet for over 5000 years, the first eruption began, lofting a volcanic column 15.5 miles (25 km) into the sky. This initial eruption was heard over 621 miles (1000 km) away.
On April 10, 1815, a series of eruptions began, culminating to the largest eruption in recorded history. The eruption lasted several days. It blew a chunk off the mountain almost a mile wide.
The volcanic column, after flying 25 miles (40 km) into the sky, returned to the ground, creating a huge pyroclastic flow of ash, pumice, and debris. The pyroclastic flow alone killed more than 10,000 people in its path. The ash that fell from Tambora travelled as far as 800 miles (1300 k) away.
When the pyroclastic flow reached the ocean, the debris created such a large displacement of water that tsunamis as high as 16 feet emanated out from the island. These tsunamis caused flooding, devastation, and death on many of the other Indonesian islands.
After the eruption was over, and estimated 100-150 cubic kilometers of ash and debris were said to have been ejected from the mountain. [for reference, in 1980, Mt. St. Helen's ejected about one or two cubic kilometers]- see graph right.
Volcanoes are measured by a Volcano Explosivity Index (VEI), on a scale of 1-8. Tambora had a VEI of 7. Only 4 other volcanoes in the last 10,000 years have had a VEI that high, and Tambora is the only volcano in recorded history with a VEI of 7.
The giant crater left at the top of the volcano 4 miles wide and 3,640 ft. deep, a hole that is still quite obvious today. The ash that fell from the eruption at Tambora was devastating, killing all the crops and vegetation, causing more than 80,000 more deaths from famine and disease.
This death count is the largest from any volcano eruption in recorded history. In addition, the amount of sulphur dioxide that was released into the stratosphere made 1816 the year without a summer.
In 1816, the overall temperature on Earth, specifically in the Northern Hemisphere, lowered so drastically that it became known as the year without a summer. Weather was disturbed all over, with problems in Western Europe and the United States, as well as Asia. Monsoon season was affected, which is thought to also be tied to a cholera epidemic that year. In places like New England and Canada, frost was recorded in every month of the year, and snow fell in June.
The summer temperatures in 1816 averaged just a few degrees below normal, but as mentioned, it frosted throughout the summer. The highs were still close to 100 degrees Fahrenheit on some days.
However, the cold spells, especially at night, caused massive crop failure, and, as a result, even more famine.
Why? 200 million tons of sulphur dioxide was shot up into the stratosphere. The sulphur dioxide prevented much sunlight from reaching the Earth’s surface, lowering the overall temperature, and killing crops and many creatures as a result. This crop failure caused mass famine, which was what caused the death toll to be so high.
The global changes in temperature did not occur until a year later. This delay was due to the fact that the stratospheric winds take that long to distribute the sulphur dioxide and volcanic ash all around the world.