Scientists warn of the threat of a catastrophic eruption of the Toba supervolcano in Indonesia

Geologists studying the dormant supervolcano Toba on the island of Sumatra in Indonesia, have found signs that in its depths continues to accumulate magma. This is evidenced by the slow rise of a dome of frozen lava in the caldera of the volcano. The results of the study are published in the journal Communications Earth & Environment.

The eruption of any of the supervolcanoes, of which there are currently about two dozen on Earth, could not only provoke a global climate change, but also to be catastrophic for all life. Therefore, scientists are trying to understand in as much detail as possible the mechanisms that lead to the formation of huge amounts of molten magma under supervolcanoes.

Experiments and numerical simulations show that supervolcanoes erupt because liquid magma rises through the earth’s crust-as it rises from a depth of more than ten kilometers, it expands sharply, leading to an explosion and a catastrophic eruption.

Scientists use geophysical equipment to monitor the subsurface state under supervolcanoes so as not to miss the beginning of the rise of liquid magma, which, according to geological data, occurs every few tens of thousands of years.
Researchers from the U.S., Germany, Australia and Indonesia have studied the composition of solidified magma supervolcano Toba and determined by the isotopic composition of argon and helium in the minerals – feldspar and zircon – the age of layers of volcanic rocks.

The authors found that major eruptions occurred at intervals of about 17,000 years, but that the volcano maintained some activity in between. These data challenged the generally accepted theory that supervolcanoes are not dangerous between episodes of large eruptions.

“Understanding what happens during these long periods of quiescence will help us predict future eruptions of young, active supervolcanoes,” Martin Danišík, associate professor of geology at Curtin University in Australia, one of the study’s authors, quoted in a press release.

Using geochronological data and thermal modeling, the authors proved that for five to thirteen thousand years after each major Toba volcanic eruption, magma continued to slowly flow into the volcano’s caldera, gradually lifting solidified lava layers like a giant tortoise shell.

“The findings force a rethinking of existing knowledge and methods of studying supervolcanoes, which typically involve looking for liquid magma beneath them to assess future hazards. We must now consider that eruptions can occur even if there is no hotbed of liquid magma under the volcano,” says Danisic. – Our results show that the hazard does not disappear with a super eruption, and the threat of new hazards still exists many thousands of years later.”

The authors point out that it is not the presence of magma beneath a supervolcano itself that is crucial for understanding the risks of new eruptions, but its condition, rate of accumulation and dynamics of spreading in the Earth’s crust.

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