Seismic analysis of the interior of the Yellowstone volcano showed that a powerful plume is hidden under it - a vertical flow of magma rapidly rising from the depths of the Earth's mantle, according to an article published in the journal Nature Geoscience.
“The history of the birth of this supervolcano, located inside the continental plate, has been hotly debated among scientists for a long time. Some colleagues believe that the cause of its appearance is a plume, and their opponents say that it arose as a result of processes in the upper layers of the mantle that are still unknown to us. We found unequivocal evidence in favor of the first hypothesis,”the authors of the discovery write.
Yellowstone supervolcano today is a giant funnel 72 kilometers long and 55 kilometers wide, which is located in the national park of the same name in Wyoming. In the middle of the last century, scientists found out that this depression is the mouth of an ancient volcano, with a giant magma chamber located at a depth of about 8 kilometers.
Further observations of Yellowstone showed that it has erupted several times over the last million years, and that these eruptions were catastrophic in nature, capable of changing the planet's climate. On the other hand, scientists have not been able to find an obvious source of its lava and magma, which makes geologists today fiercely debate the possible reason for the appearance of a giant volcano in this part of the United States.
Peter Nelson and Stephen Grand, geologists at the University of Texas at Austin, USA, have opened a new chapter in this debate. They found new evidence that under Yellowstone is a kind of "fountain" of extremely hot and liquid magma, rapidly rising to the surface of the Earth from the deepest layers of its interior, located on the border between the core and the mantle.
Such magma flows, similar in shape to a mushroom, are called plumes by scientists. Plumes, due to their high speed of movement and high temperature, can sometimes "break through" thick and cold rocks of the continental crust and emerge to the surface of the planet, causing powerful volcanic eruptions.
Geologists, according to Nelson and Grand, have long suspected that a plume may be lurking under Yellowstone, but until now they have not had unequivocal evidence that it exists. This led many "skeptics" to believe that in fact this flow of hot matter was generated by fragments of the sea plate, which had long sunk under North America, but had not yet disintegrated into pieces.
Scientists in Texas proved that this is not the case by analyzing how two rare types of seismic waves passed through Yellowstone National Park and the Earth's core using a network of USArray seismographs. A large number of these detectors have helped geologists to draw up a three-dimensional map of the bowels of the volcano and understand how exactly magma rises to its surface.
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As these measurements showed, under Yellowstone there is a rather narrow and straight magma "tube", which goes deep into the Earth for about 2.7-3 thousand kilometers. Its properties and dimensions, as the scientists note, unambiguously indicate that it was generated by a plume, whose temperature was higher than that of the surrounding rocks, by about 600-850 degrees Celsius.
This discovery, as the geologists emphasize, does not yet allow us to say when the next supervolcano eruption will occur and does not make it more likely. On the other hand, further observations of the plume's behavior, Grand and Nelson hope, will help scientists understand in advance that the volcano has begun to wake up.
