A dormant supervolcano lying beneath Lake Toba in Indonesia has the potential to erupt again, scientists have said.
Geologists believe Mount Toba, which has erupted at fairly regular intervals over the last 1.2 million years, still poses a threat with its huge magma chamber and should be studied to assess the risk of a fresh eruption.
The president of the Indonesia Geological Experts Association, Rovicky Dwi Putrohari, has told the Jakarta Post about the danger Mount Toba poses.
"Our researchers were able to find the location and dimensions of the magma chamber of Mount Toba," he said. "Later research will find out the potential volume of magma in the volcano for triggering an eruption."
Tomography studies detected the magma chamber beneath Lake Toba. They found it was located at a depth of between 20 and 100km.
Putrohari said that a number of studies relating to the supervolcano were presented during a three-day conference held by the Indonesian Geological Experts Association and the Indonesian Geophysics Experts Association.
Studies showed that Mount Toba has erupted four times in the past - 1.2 million years ago, at 840,000 years ago, 500,000 years ago and then again around 74,000 years ago.
The last eruption is recognised as the biggest known eruption ever to have taken place on Earth. The Toba catastrophe theory relating to this eruption suggests the event caused a decade-long global volcanic winter that was possibly followed by 1,000 years of cooling.
The blast was 100 times greater than the largest volcanic eruption in recent history - Mount Tambora in 1815.
Indonesia has around 120 active volcanoes currently being monitored, one of which has become increasingly active in recent months. Mount Sinabung spewed ash 7km into the sky earlier this month, leading over 1,600 to evacuate their homes.
Putrohari said the magma chamber still inside Mount Toba could erupt at any time if the Sumatra fault line reactivated, as it runs directly through the volcano.
"A quake could reactivate the magma chamber which is so far dormant. That's why we believe Mount Toba could erupt again at any time. When it will be, we don't know. Thorough and continuous research is needed to find that out."
Andi M Adiwinata, from the Indonesian Geophysics Experts Association, added: "The researchers are currently working to find out how big the potential threat from Mount Toba is. Despite being categorised as inactive, its development needs further monitoring."