Experts report that in some places, significantly raising the soil to 10 inches.
Scientists report that the Yellowstone supervolcano National Park, only a "sigh", triggering a sharp rise of the soil for miles around.
Seething volcano erupted powerfully tripled over the past 2.1 million years — each of these eruptions were more powerful than the Mount St. Helena in 1980. Yellowstone caldera, which covers 25 to 37 (40 to 60 km) mile strip of Wyoming, is an ancient crater formed as a result of the last big blast 640,000 years ago.
(See "When Yellowstone blows up" in the magazine National Geographic)
Since then, the 30 smaller eruptions — including what happened 70,000 years ago — have filled the caldera with lava and ash, forming a relatively flat landscape that we see today.
However, beginning in 2004, scientists noticed that the soil above the caldera rise each year to a value of 2.8 inches (7santimetrov). (See also: "Yellowstone rises swollen supervolcanoes")
This has declined between 2007 and 2010 to a centimeter or less per year. However, since the volcano began to swell, the level of the soil above it in places up to 10 inches (25 centimeters).
"This is an unusual crustal uplift, as he is exposed to a large area and the rates are high," says Bob Smith (University of Utah), a long time student of volcanism of Yellowstone.
Scientists believe that the inflated magma pool, located between 4 and 6 miles (7 to 10 miles) below the earth's surface, causing the rise of the soil. "Luckily, it seems that this rise is not a harbinger of imminent catastrophe," says Smith.
(See also: "Under the Yellowstone magma chamber is, 20% more than expected.")
"At first we were concerned that this could lead to the eruption," said Smith, a co-author of the rise of the soil, published December 3, 2010., Publication Geophysical Research Letters
"But when we saw the magma at a depth of ten kilometers, we stopped worrying. If she was at a depth of two or three kilometers, to worry about it would be much more. "
He added that the study of lifting soil can shed light on what is happening in the underground tunnels of the volcano, which in turn may help scientists predict the next "exhalation" Yellowstone volcano.
Smith and colleagues at the American Geological Observatory Yellowstone volcano research reflected the rise and fall of the caldera, using the global navigation and positioning (GPS) and interferometric synthetic aperture radar (InSAR), which provide measures of deformation of the soil.
Deformation of the soil may involve the movement of magma to the surface before the eruption. For example, the slopes of Mount St. Helena increased significantly in the months before the eruption in 1980.
However, there are other examples, including the Yellowstone supervolcano, when the rise and fall of the soil for thousands of years does not lead to eruption.
According to current theory, the magma pool is fed by a stream in Yellowstone hot rock rising from the level of the Earth's mantle. (See also "found a new layer of magma deep in the Earth's mantle?")
When the amount of magma flowing into the chamber increases, the pool swells like the light and the surface of the earth above it rises. Figures show that in the recent rise of the collector was filled with 0.02 cubic miles (0.1 cubic kilometer) of magma a year.
According to theory, the growth rate slows, likely that magma is moving horizontally, cools and hardens, allowing to stabilize the surface.
"On the basis of geological evidence, Yellowstone probably been continuous cycle of ups and downs over the past 15,000 years, and this cycle is likely to be continued" — says Smith.
Studies show that the caldera rose about 7 inches (14 cm) between 1976 and 1984, before the newly reset 5.5dyuymov (14 centimeters) in the next decade.
"These calderas tend to go up and down, up and down," he said. "But every time they" breathe ", creating geothermal explosions, earthquakes, or, ultimately, they can cause volcanic eruptions.
Associated with a rise of Yellowstone geysers and earthquakes?
Predict when an eruption might occur is extremely difficult, in part because the details of what's going on under Yellowstone, are still uncertain. Moreover, the continuous recording activity of Yellowstone have been made only in the 1970's. — A tiny segment of geological time — which makes it difficult to draw conclusions.
"Clearly, there is a source of magma that feeds Yellowstone, and since Yellowstone has erupted in the recent geological past, we know that there is magma at shallower depths," — said Dan Dzurisin, expert of Yellowstone Volcano Observatory Cascades in Washington (U.S. Geological Survey).
"Magma has to be in the crust, or we would not have geothermal activity, which takes place to be" — added Dzurisin. "Who comes from Yellowstone so much heat that if he had not been fueled by magma, the whole system would be cool since the last eruption, which occurred 70,000 years ago."
Huge hydrothermal system, located just beneath the surface of Yellowstone, which in turn contains a lot of interesting attractions of the park may also play a role in the rise of the soil, even though no one is quite certain to say how important this role, "- says Dzurisin.
"Could it be that the rise was due to no moving magma and hydrothermal system, which is sealed and pressurized?" — He asks. "And then it subsides when the system flow and pressure drops? In these parts and is the difficulty. "
Not of particular importance of monitoring how the soil is raised and lowered. Different areas may move in different directions and connected by unknown ways, reflecting the as yet unmapped volcanic and hydrothermal system of canals.
About 3,000 earthquakes in Yellowstone may provide more clues about the connection between the rise of the soil and the magma chamber.
For example, between 26 December 2008 and 8 January 2009 area around Yellowstone Lake has undergone about 900 earthquakes
"This series of earthquakes may have helped ease the pressure in the magma pool, allowing the fluid to come out, and it reduced the level of recovery of the soil," said Smith of the University of Utah (See also: "The mysterious series of earthquakes struck the waters of Oregon").
"Large earthquakes may be related to the rise of soil deformation caused by the passage of magma," — he said.
"How these penetration causing damage to nearby areas, or how they can transfer the voltage on the magmatic system — so this is an important new area of research."
Overall, Dzurisin (USGS) said, "History of Yellowstone is more complicated because of the appearance of all the best technologies to study it."
For National Geographic News