New research has traced the origins of some of Earth’s most powerful volcanic eruptions to mysterious continent-sized structures deep within our planet.
These formations, known as BLOBS—short for Big LOwer-mantle Basal Structures—are providing scientists with a deeper perspective on the geological processes uniting activity in Earth’s lower mantle to potentially cataclysmic surface events.
The new research, published in Communications Earth and Environment, combines seismic data and geodynamic modeling to reveal how giant columns of hot rock, known as mantle plumes, arise from these massive structures, revealing them as the driving force behind surface eruptions.
Offering the strongest evidence yet that Earth’s most destructive volcanic events, including those linked to extinctions, are triggered by interactions between BLOBS and mantle plumes, the new study traces their origins to areas more than 2,000 kilometers underground.
Unearthing BLOBS
BLOBS, as their moniker would suggest, are expansive hot regions that exist at the very bottom of Earth’s mantle at depths between 2,000 and 3,000 kilometers. These enigmatic structures were first identified beneath the Pacific Ocean and Africa, and geologists believe them to be composed of chemically distinct material compared to the surrounding mantle rock.
Although the existence of BLOBS has been known to geologists for some time, their role in shaping the Earth’s surface geology have remained largely mysterious. Among the many questions geologists have had include whether they are mostly stationary features, or if BLOBS move in response to mantle convection.
The connection between these massive structures and volcanic activity has also long been suspected, although the mechanism that links them to surface eruptions has remained largely elusive, until now.
BLOBS and Volcanic Eruptions
In the recent study by the international team, led by University of Wollongong, Australia researcher Annalise Cucchiaro, the team modeled mantle convection processes spanning a period of one billion years. Through their simulations, the team revealed that the lollipop-shaped mantle plumes appear to arise directly out of moving BLOBS.
Through their movement, these plumes carry heat upward over extensive periods spanning tens of millions of years, slowly ascending until they reach the upper mantle, where lower pressure accumulations help the solid rock to melt and erupt at the surface.
The heads of these plumes are largely responsible for sudden and massive eruptions, resulting in the formation of massive regions of igneous rock and oceanic plateaus, with examples including the Ontong Java-Manihiki-Hikurangi complex in the southwest Pacific. On the opposite end of the plumes, their tails have now been connected to long volcanic chains like the Hawaii-Emperor and Lord Howe seamount chains.
Matching the Geologic Record
By predicting plume locations alongside the known distribution of ancient volcanic eruptions that have long been preserved in the ocean floor over tens of millions of years, the team was able to test the accuracy of their models, revealing a strong statistical correlation.
Additionally, Cucchiaro and her team found that several of the eruption sites they examined were positioned very near the modeled paths of moving BLOBS, and even directly above them in some instances. Instances where eruption sites were found to be offset from the paths of BLOBS led the researchers to suggest tilted plumes, which likely result from complexities in mantle flows, to account for the apparent deviation.
The team then compared the locations of eruptions to 3D seismic tomographic images of the Earth’s interior, which they assembled from data associated with distant earthquakes. Of the four models they tested, one revealed an alignment between eruption locations over the past 300 million years, which Cucchiaro and the team interpret to mean that some BLOBS have, for the most part, remained stationary in recent geologic history.
BLOBS: A Slow but Powerful Force
A key finding from the team’s research was the revelation that the Earth’s deep interior is much more dynamic than past research had shown.
As BLOBS move over time, they influence the path of rising mantle plumes, as well as the timing of surface eruptions. While these motions occur at a glacial pace—the researchers estimate their movement to be around one centimeter per year—they can nonetheless shift the BLOBS by hundreds of kilometers over the passing of millions of years.
Going forward, the team plans to continue their investigations by probing the chemical composition of these structures, as well as the conduits that link them to the surface, with the help of simulations that will allow them to explore the ways they have evolved over time.
Even though these processes are occurring far beneath the surface world, and at a pace so slow that it is virtually imperceptible, the team’s findings nonetheless reveal that they can still have dramatic effects, which include the shaping of continents. Even more broadly, the potential for catastrophic volcanic activity related to these processes throughout geologic history has likely also served as a driver of extinction events and other major changes that have helped shape the fate of the planet throughout its history.
The team’s paper, “Large volcanic eruptions are mostly sourced above mobile basal mantle structures,” appeared in Communications Earth & Environment on July 9, 2025.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.