Scientists have proposed a new explanation for what fuels the Yellowstone supervolcano, challenging the long-held belief that it is fed by a deep plume of molten rock rising from Earth’s interior.
A new study published in the journal ‘Science’ suggests that Yellowstone’s magma is instead supplied by a broad underground flow of hot rock, described as a “mantle wind,” moving through the upper mantle beneath North America.
Supervolcanoes are capable of producing the largest volcanic eruptions on Earth, releasing more than 1,000 cubic kilometres of magma, rock and ash. Such eruptions can have far-reaching effects on global climate, ecosystems and human societies, making it important for scientists to understand how these massive volcanic systems develop.
Researchers from the Institute of Geology and Geophysics of the Chinese Academy of Sciences created a detailed three-dimensional model of western North America to study how the Earth's outer shell, known as the lithosphere, and the underlying mantle interact.
Their findings suggest that the hot material feeding Yellowstone comes from the shallow asthenosphere, a softer layer beneath the lithosphere, rather than from a deep mantle plume.
The study also challenges the traditional idea that supervolcanoes contain huge, long-lasting chambers of liquid magma beneath the surface.
Instead, researchers say the magma is spread through vast regions of partially molten rock called "magma mush" systems. These thick, semi-solid zones extend across large sections of the lithosphere and may only produce smaller liquid-rich magma pockets shortly before an eruption.
Yellowstone, located in the western United States, has experienced two supereruptions over the past 2.1 million years, making it one of the world’s best-studied supervolcanoes.
Previous research had identified a large magma mush system beneath Yellowstone, but the source of the magma and the forces shaping it remained uncertain.
According to the new model, the underground mantle wind was created by the long-term movement of the ancient Farallon Plate, whose remnants still lie deep beneath central and eastern North America.
As this hot mantle material flows eastward beneath the continent, it is forced downward under the thick lithosphere. The resulting stretching causes pressure to drop, allowing rock to melt and form magma.
The researchers also found that opposing forces beneath Yellowstone gradually pull apart the continental lithosphere, creating a southwest-sloping pathway that allows magma to rise and evolve over time.
They say the model closely matches existing geological and geophysical observations from the Yellowstone region.
The researchers believe their findings provide one of the clearest explanations yet of how giant magma systems develop beneath supervolcanoes. The study also offers a possible mechanism for maintaining the long-lived magma mush systems believed to exist beneath many of the world's supervolcanoes.