With a VEI of 7, the explosion of the mount Tambora before sundown, on 10 April 1815, on the island of Sumbawa in Indonesia, is the largest ever volcanic eruption in recorded history.
Scientists have developed the Volcanic Explosivity Index (VEI), a relative measure of the explosiveness of volcanic eruptions. VEI 8 is the highest index. There haven’t been any VEI-8 volcanoes in the last 10,000 years.
Before the eruption, the height of Mount Tambora might have been 4,300 meters. In a matter of a day the mountain lost almost 2 km. The shattering blast that blew the mountain apart was heard on Sumatra, more than 2,000 km away and Sir Stamford Raffles, founder of Singapore, thought it was a cannon fire. Volume of ejecta was estimated at 160 km3 and heavy volcanic ashfalls were observed as far away as Borneo, Sulawesi, Java, and the Maluku Islands. The death toll was at least 71,000 people, of whom about 12,000 were killed directly by the eruption. So much ash and sulfur dioxide were sent into the atmosphere that it blocked the sun and caused the average global temperature to drop 2 deg. C. The year 1816 became known as the “Year Without a Summer”. A devastating famine rolled over Central Europe, in India, monsoon rains stopped causing crops to fail and later triggering severe flooding. A persistent dry fog was observed in parts of the eastern U.S. In upstate New York temperatures went below freezing almost every day in May leaving the ground frozen solid until mid-June. High levels of tephra in the atmosphere led to unusually spectacular sunsets during this period. Resettlement of the mountain began in 1907. In 1930 a coffee plantation was started on the northwestern slope of the mountain. The Swiss teacher and botanist Heinrich Zollinger was the first climber to reach the eastern rim of the Tambora caldera after the eruption of 1815. He made his ascent in 1847 with the help of a native team. The volcano remains active with smaller eruptions taking place in 1880 and 1967. Episodes of increased seismic activity were reported in 2011, 2012, and 2013.
(Image: Mount Tambora eruption with ashes thickness)