Supervolcanes accumulate tremendous amounts of lava prior to eruptions in horizontal sheets dubbed "magma pancakes", experts have said.
Researchers investigating super-eruptions at Lake Toba in Indonesia were looking to find out how the huge amounts of eruptible material needed by supervolcanoes accumulate in the Earth's crust and where it originates from.
Published in the current issue of Science, an international team of geoscientists asked if the eruption at Lake Toba 74,000 years ago could happen again.
The super-eruption at Lake Toba was the biggest in Earth's recent history. Unlike large volcanic eruptions, Toba emitted 2,800 cubic kilometres of volcanic material, causing a massive impact on the climate and environment and forming the 80km long Lake Toba.
Previously, researchers had suspected the huge amounts of lava from super-eruptions had accumulated over millions of years.
Supervolcanoes are found in a number of other parts of the world, including Yellowstone Volcano in the US, volcanoes in the Andes, and the caldera of Lake-Taupo in New Zealand. They erupt every couple of hundred thousand years in gigantic explosive events.
Researchers believe their findings will help our understanding of the processes that lead to super-eruptions.
Experts from the GFZ German Research Centre for Geosciences used a seismometer network in the Toba area to find out more about the lava's origin.
Over six months, they recorded seismic noise and natural vibrations. After analysing their findings, the scientists found that the deposits from the last eruption lying below 7km consisted of horizontal magmatic intrusions that still contained molten material, similar to a pile of pancakes.
GFZ scientist, Christoph Sens-Schönfelder, a co-author of the study said: "With a new seismological method we were able to investigate the internal structure of the magma reservoir beneath the Toba-caldera. We found that the middle crust below the Toba supervolcano is horizontally layered."