Post by KNOWTHIS on Dec 19, 2006 2:28:16 GMT -5
www.billingsgazette.net/articles/2006/12/15/news/state/25-dome.txt
Yellowstone domes rising at 'really pronounced' pace
Parts of the collapsed, restless volcano in Yellowstone National Park are swelling faster than has ever been recorded.
Geologists from the University of Utah say two domes inside the Yellowstone caldera have steadily inflated at two to three times the rate as some of the most rapid movements recorded between 1923 and 1984.
"We've gone to this really pronounced, and I would say unprecedented, uplift of the caldera," said Bob Smith, a Utah geologist and one of the leading researchers into Yellowstone's busy volcanic life.
Smith presented some of the new findings Wednesday to the American Geophysical Union meeting in San Francisco.
Today, Smith is scheduled to present new information about the vast, fiery hot spot that has fueled Yellowstone for millions of years. One finding is that the tilting plume extends at least 390 miles below the surface.
The new research, including discussion of the origin and evolution of the Yellowstone hot spot, may help put an end to several years of debate about what kind of plume underlies the park.
Like a piece of paper moving over a candle, the Earth's crust has drifted over the hot spot for millions of years, destroying mountains and leaving a 300-mile-wide valley known as the Snake River Plain in Idaho.
The activity had a significant role in shaping landscapes in the West, from drainages and valleys to seismic drama playing out beneath the surface.
"It's had a really profound effect over a much larger area than just Yellowstone," Smith said.
Yellowstone's geology was a hot topic at the AGU meeting. More than 60 presentations touched on the park, whether it was looking at the diet of ancient wolves or activities of helium isotopes.
In recent years, much attention has been focused on so-called "huffing and puffing" of the Yellowstone caldera, the huge collapsed volcano that stretches across the park's middle.
The caldera has been rising and falling for at least 15,000 years, sometimes swinging more than 10 feet.
Portions of the caldera rose more than 3 feet between 1923 and 1984 and then dropped nearly 8 inches from 1985 to 1995. Measurements in 1995 and 1996 showed it rising again before starting to fall in 1997.
The latest upward motion has been unusual for its speed.
Using data collected on the ground and from satellites, scientists say the Mallard Lake Dome, west of Yellowstone Lake's West Thumb, has inflated by 4 centimeters a year since the middle of 2004, while the Sour Creek Dome north of Fishing Bridge has increased by about 6 centimeters a year. (One inch is 2.54 centimeters.)
Smith said the activity may be spurred by an infusion of magma from below that's heating up fluids and causing the ground to bulge.
"It's like inflating the balloon but the balloon is capped," Smith said. "Eventually that fluid's got to go somewhere."
While most of the caldera has been inflating, another nearby area has been falling.
A newly discovered bulge just outside the caldera, near Norris Geyser Basin, has fallen by about an inch since 2004.
But in the preceding six years - from 1997 to 2003 - the dome grew by about 5 inches and may have triggered some of the unusual activity at Norris, including a sudden rise in temperatures, the formation of explosive new steam vents and the reawakening of Steamboat geyser, the world's tallest.
When the dome, called the North Rim Uplift, began deflating again, temperatures at Norris dropped, Steamboat stopped erupting and the steaming vents at nearby Nymph Lake died down.
The below-ground connections between the ups and downs at Norris and domes inside the caldera are still unknown.
And what it all adds up to in the big picture is also unclear - except that Yellowstone continues to be geologically active and few things stay static for long.
In recent years, the possibility of a large volcanic eruption has been a popular media topic, but Smith said the scenario seems overhyped. A more likely possibility would be a large earthquake, he said, noting that the most powerful quake in the interior Western United States happened at Hebgen Lake on Aug. 17, 1959.
"It's a much higher risk," he said.
Yellowstone domes rising at 'really pronounced' pace
Parts of the collapsed, restless volcano in Yellowstone National Park are swelling faster than has ever been recorded.
Geologists from the University of Utah say two domes inside the Yellowstone caldera have steadily inflated at two to three times the rate as some of the most rapid movements recorded between 1923 and 1984.
"We've gone to this really pronounced, and I would say unprecedented, uplift of the caldera," said Bob Smith, a Utah geologist and one of the leading researchers into Yellowstone's busy volcanic life.
Smith presented some of the new findings Wednesday to the American Geophysical Union meeting in San Francisco.
Today, Smith is scheduled to present new information about the vast, fiery hot spot that has fueled Yellowstone for millions of years. One finding is that the tilting plume extends at least 390 miles below the surface.
The new research, including discussion of the origin and evolution of the Yellowstone hot spot, may help put an end to several years of debate about what kind of plume underlies the park.
Like a piece of paper moving over a candle, the Earth's crust has drifted over the hot spot for millions of years, destroying mountains and leaving a 300-mile-wide valley known as the Snake River Plain in Idaho.
The activity had a significant role in shaping landscapes in the West, from drainages and valleys to seismic drama playing out beneath the surface.
"It's had a really profound effect over a much larger area than just Yellowstone," Smith said.
Yellowstone's geology was a hot topic at the AGU meeting. More than 60 presentations touched on the park, whether it was looking at the diet of ancient wolves or activities of helium isotopes.
In recent years, much attention has been focused on so-called "huffing and puffing" of the Yellowstone caldera, the huge collapsed volcano that stretches across the park's middle.
The caldera has been rising and falling for at least 15,000 years, sometimes swinging more than 10 feet.
Portions of the caldera rose more than 3 feet between 1923 and 1984 and then dropped nearly 8 inches from 1985 to 1995. Measurements in 1995 and 1996 showed it rising again before starting to fall in 1997.
The latest upward motion has been unusual for its speed.
Using data collected on the ground and from satellites, scientists say the Mallard Lake Dome, west of Yellowstone Lake's West Thumb, has inflated by 4 centimeters a year since the middle of 2004, while the Sour Creek Dome north of Fishing Bridge has increased by about 6 centimeters a year. (One inch is 2.54 centimeters.)
Smith said the activity may be spurred by an infusion of magma from below that's heating up fluids and causing the ground to bulge.
"It's like inflating the balloon but the balloon is capped," Smith said. "Eventually that fluid's got to go somewhere."
While most of the caldera has been inflating, another nearby area has been falling.
A newly discovered bulge just outside the caldera, near Norris Geyser Basin, has fallen by about an inch since 2004.
But in the preceding six years - from 1997 to 2003 - the dome grew by about 5 inches and may have triggered some of the unusual activity at Norris, including a sudden rise in temperatures, the formation of explosive new steam vents and the reawakening of Steamboat geyser, the world's tallest.
When the dome, called the North Rim Uplift, began deflating again, temperatures at Norris dropped, Steamboat stopped erupting and the steaming vents at nearby Nymph Lake died down.
The below-ground connections between the ups and downs at Norris and domes inside the caldera are still unknown.
And what it all adds up to in the big picture is also unclear - except that Yellowstone continues to be geologically active and few things stay static for long.
In recent years, the possibility of a large volcanic eruption has been a popular media topic, but Smith said the scenario seems overhyped. A more likely possibility would be a large earthquake, he said, noting that the most powerful quake in the interior Western United States happened at Hebgen Lake on Aug. 17, 1959.
"It's a much higher risk," he said.