What triggered biggest volcanic eruption found

​London: Researchers have decoded what triggered one of the largest volcanic eruptions witnessed by mankind about 73,000 years ago, when extraordinary volumes of volcanic ash were ejected into the atmosphere and rained down and covered enormous areas in India and Indonesia.

The volcano's secret was revealed by geochemical clues hidden inside volcanic quartz crystals. The deadliest volcanoes on Earth are called supervolcanoes, capable of producing cataclysmic eruptions that devastate huge regions and cause global cooling of the climate.

The Indonesian supervolcano Toba had one of these eruptions about 73,000 years ago, when 2,800 cubic kilometres of volcanic ash was ejected into the atmosphere and rained down and covered enormous areas in Indonesia and India.

Scientists have long debated how these extraordinary volumes of magma are generated, and what makes this magma erupt so very explosively.

A team of researchers at Uppsala University in Sweden, together with international colleagues, have now found intriguing clues hidden inside millimetre-sized crystals from the volcanic ash and rock.

"Quartz crystals that grow in the magma register chemical and thermodynamical changes in the magmatic system prior to eruption, similar to how tree rings record climate variations," said David Budd from Uppsala University.