The Toba supervolcanic eruption in Indonesia changed the world. Erupting 2,800 cubic kilometers (672 cubic miles) of volcanic debris into the sky around 74,000 years ago, it ranked as an 8 (out of 8) on the Volcanic Explosivity Index (VEI). This made it one of the most powerful eruptions in Earth's history, and certainly the largest within the last 25 million years.
A new paper in Nature Communications reveals the sheer size of the beast that gave rise to such a catastrophic eruption. Incredibly, there is a large chamber, perhaps as far down as 150 kilometers (93 miles) within the crust, which contains as much as 50,000 cubic kilometers (roughly 12,000 cubic miles) of eruptible magma. That’s over four times the size of Lake Superior, and bigger than the one beneath Yellowstone.
It was detected using seismic waves, whose speeds through the bowels of the planet indicate precisely how molten or solid various materials are, and what they may be comprised of. One day, this monstrous magma will make its way up through the crust, accumulate pressure, and explode onto the world once again.
Thankfully, however, the team do not think that there are any signs that this supervolcano is due for another eruption anytime soon.
“I think that a huge-scale eruption should be preceded by clear precursors – earthquakes, ground deformation, fumarole activity, and so on,” lead author Ivan Koulakov, a professor of geophysics and the head of the laboratory of seismic tomography at Novosibirsk University in Russia, told IFLScience.
“On the other hand, during recent human history, there hasn’t been a supereruption. Hence, nobody knows for sure how or when it will happen.”
Lake Toba today, hiding a crater up to 100 kilometers long and 30 kilometers wide. franshendrik Tambunan/Shutterstock