Giant Blobs Under Earth’s Surface Might Trigger Deadly Volcanic Eruptions

Deep under our feet—far below tectonic plates and magma chambers—lie two gigantic, lumpy structures in the Earth’s lower mantle. They’re the size of continents and sit nearly 3,000 kilometers (about 1,865 miles) down. And according to new research, they may be the hidden trigger behind the most cataclysmic volcanic eruptions in our planet’s history.

Scientists call them “Big Low-Shear Velocity Provinces,” but that term has all the charm of a geology textbook. So researchers gave them a more fitting nickname: BLOBS, short for Big Lower-mantle Basal Structures. They’re massive, oddly shaped, and anchored at the base of the mantle. The name may sound cute, but the eruptions they help unleash are anything but.

“These plumes move along with their source, the BLOBS,” said volcanologist Annalise Cucchiaro from the University of Wollongong, whose team just confirmed that these deep-Earth formations are closely tied to surface-level volcanic events. When superheated rock—called a mantle plume—rises from a BLOBS’ edge, it can lead to the kind of Earth-shaking explosion that once helped wipe out the dinosaurs.

These Massive Underground BLOBS Could Be Steering Earth’s Most Violent Eruptions

The study, published in Communications Earth & Environment, used three separate datasets to map volcanic events stretching back 300 million years. The team also ran billion-year simulations showing how BLOBS may have shifted over time, and how that movement matched the location of known mega-eruptions. “The locations of past giant volcanic eruptions are significantly related to the mantle plumes predicted by our models,” Cucchiaro and her co-author Nicholas Flament explained in The Conversation.

Only two BLOBS have been identified so far—one under Africa, the other beneath the Pacific. Their tops are jagged and irregular, like a mountain range at the bottom of the world. They’re not fixed in place, either. They shift slowly, dragging magma plumes with them like geological puppeteers.

While these eruptions are terrifying, they can also be productive. The areas they leave behind are often rich in rare minerals, diamonds, and other materials that could help fuel the energy transition.

“This research cracks open one of the questions that has long plagued scientists,” said Flament. It may also explain why the planet sometimes decides to reset things…violently, from the inside out.