Yellowstone activity heats up
Grand Prismatic Spring, Yellowstone National Park
Friday, 09, Nov 2007 11:48
Activity beneath the surface of the Yellowstone 'supervolcano' has risen its floor at a rate of up to 7cm per year, a new study has found.
The 'volcano' is a caldera created by three giant eruptions 640,000 years ago plus many smaller eruptions over 70,000 years ago.
Researchers from the University of Utah say that the activity of magma beneath the surface of the caldera has increased since 2004 after observing satellite measurements of the area.
Writing in the Science journal they argue that this is likely to be due to a Los Angeles-sized piece of molten rock moving six miles underneath the caldera.
The movement upwards of the caldera floor is said to be more than three times greater than ever observed since measurements began in 1923.
"Our best evidence is that the crustal magma chamber is filling with molten rock," said seismologist Robert Smith.
"But we have no idea how long this process goes on before there either is an eruption or the inflow of molten rock stops and the caldera deflates again."
Other potential reasons for the uplift include a build-up of pressurised water and gases.
Smith added that "there is no evidence of an imminent volcanic eruption or hydrothermal explosion".
"A lot of calderas worldwide go up and down over decades without erupting," he said.