Scientists have discovered what causes "supervolcanoes" to erupt thousands of times larger than a normal volcano.

Originally it was believed that it took an external trigger, like an earthquake, to set off a supervolcano, but that theory was recently disproven, according to BBC News.

Research conducted at the European Synchrotron Radiation Facility, where they simulated intense pressure and heat inside supervolcanoes to try predicting future disasters,

The study was published in Nature Geoscience.

Click here to view the complete research conducted by Lead author Wim Malfait, of ETH Zurich, and his colleagues.

"We knew the clock was ticking but we didn't know how fast: what would it take to trigger a super-eruption? This is something that, as a species, we will eventually have to deal with," said Malfait, according to BBC News. "Now we know you don't need any extra factor - a supervolcano can erupt due to its enormous size alone."

There are about 20 known supervolcanoes on planet Earth, in places like Lake Toba in Indonesia, Lake Taupo in New Zealand, according to BBC News.

Supervolcanoes occur only once every 100,000 years, but when they do they have an overwhelming impact on Earth in a number of ways.

Approximately 600,000 years ago when a supervolcano erupted in Wyoming, in what is now Yellowstone National Park, it ejected over 1,000 cubic km of ash and lava, or enough to bury almost an entire large city, according to BBC News.

"This is something that, as a species, we will eventually have to deal with. It will happen in future," said Malfait. "You could compare it to an asteroid impact - the risk at any given time is small, but when it happens the consequences will be catastrophic."

Researchers visited ESRF to use an experimental station known as the high pressure beamline to simulate intense pressure and heat inside a supervolcano. To do so, they put synthetic magma into a diamond capsule and used x-rays to look for changes as the mixture "reached high pressures" according to the study.

"If we measure the density difference from solid to liquid magma we can calculate the pressure needed to provoke a spontaneous eruption," Mohamed Mezouar, an ESRF scientist, said in a statement to BBC News. "To recreate the conditions in the Earth's crust is no trivial matter, but with the right vessel we can keep the liquid magma stable up to 1,700C and 36,000 atmospheres."

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