London, August 9 : U.S. researchers say that the relatively tepid temperature of the Yellowstone Caldera indicates that the supervolcano may be on its last legs.
Derek Schutt of Colorado State University has revealed that the supervolcano in Yellowstone National Park has been found to be about 1450 degree Celsius hot at 80 kilometres beneath the Earth's surface, which is only lukewarm for a supervolcano.
He and his colleague Ken Dueker, a researcher from the University of Wyoming, estimated the temperature of the plume beneath the Snake River Plain, south-west of the Yellowstone caldera, using the knowledge that temperature affects how seismic waves travel through rocks.
"80 km beneath the Snake River Plain, seismic waves travel slower than just about anywhere on Earth at this depth," New Scientist magazine quoted Schutt as saying.
The researchers reckoned that the temperature at that depth was likely to be between 50 to 200 degree Celsius hotter than the surrounding rock, at least 1450 degree Celcius.
Thought there is no way to reach these temperatures without a plume of magma rising up from deep inside the Earth, the researchers say, "this is much colder than other presumed mantle plumes, such as Hawaii."
Based on their observations, the researchers came to the conclusion that the plume might have disconnected from its heat source in the Earth's core.
If the researchers' surmise is true, it means the plume could be dying, and the sequence of mega-eruptions could come to an end.
"If it doesn't have clear source, as it rises eventually the plume will die out," says Schutt.
Jacob Lowenstern of the US Geological Survey's Yellowstone Volcano Observatory, however, cautions that it does not mean that there will not be another eruption.
"Regardless of the ultimate origin of the plume, the volcanic hazard remains about the same," he said.
Rhodri Davies of Imperial College London agrees, saying that even if Schutt and Dueker's temperature estimates are correct, there is still enough heat there to trigger eruptions.
"I would suspect there is life in the Yellowstone hotspot. To me, ruling out a future catastrophic eruption would be foolish," he says.
The study has been reported in the journal Geology.