Yellowstone Has Bulged as
Magma Pocket Swells
Some places saw the ground rise by ten
inches, experts report.
Brian Handwerk for National Geographic News
Published January 19, 2011
Yellowstone National Park's supervolcano
just took a deep "breath," causing miles of
ground to rise dramatically, scientists
The simmering volcano has produced major
eruptions—each a thousand times more powerful than Mount St. Helens's 1980
eruption—three times in the past 2.1 million years.
Yellowstone's caldera, which covers a 25- by
37-mile (40- by 60-kilometer) swath of Wyoming, is an ancient crater formed
after the last big blast, some 640,000 years ago.
Since then, about 30 smaller
eruptions—including one as recent as 70,000
years ago—have filled the caldera with lava and
ash, producing the relatively flat landscape we
But beginning in 2004, scientists saw the ground
above the caldera rise upward at rates as high
as 2.8 inches (7 centimeters) a year.