Yellowstone Caldera Rising at Record Rate
UPI
SALT LAKE CITY, Nov. 27 U.S. seismologists said the Yellowstone caldera has been rising at a record rate since 2004 but there's no evidence of an imminent volcanic eruption.
Image: The Yellowstone Caldera, the oval depression, 53 miles long and 28 miles across (outlined in bright orange), lies in the middle of the park. This caldera was formed 640,000 years ago during the most recent of Yellowstone's great volcanic eruptions. In that eruption, 240 cubic miles (1,000 km3) of molten rock (magma) was blasted into the atmosphere and scattered on the Earth's surface-more than 1,000 times the volume erupted at Mount St. Helens in 1980! The ground then collapsed into the partly emptied magma reservoir, forming an enormous craterlike depression.
University of Utah Professor Robert Smith said the rise is likely due to a huge area of molten rock forming 6 miles beneath the caldera.
"There is no evidence of an imminent volcanic eruption or hydrothermal explosion. That's the bottom line," said Smith, lead author of the study. "A lot of calderas (volcanic craters) worldwide go up and down over decades without erupting."
Smith, researcher Wu-Lung Chang and colleagues said the upward movement -- nearly 3 inches annually for the past three years -- is more than three times greater than ever observed since such measurements began in 1923.
"Our best evidence is the crustal magma chamber is filling with molten rock," said 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."
The study, which included doctoral students Jamie Farrell and Christine Puskas, with geophysicist Charles Wicks of the U.S. Geological Survey, appeared in the Nov. 9 issue of Science.
http://www.upi.com/NewsTrack/Science/2007/11/27/yellowstone_caldera_rising_at_record_rate/7100/
http://www.standeyo.com/NEWS/07_Earth_Changes/071128.Yellowstone.html