Though barely perceptible to all but the most well-trained eye, Yellowstone National Park has been rising at an alarmingly fast rate - up to 3 inches a year since mid-2004 - according to a new study published in the journal Science. A buildup of magma about 6 miles, or 10 km, underground is causing the surface to almost visibly "inflate".
The park is located on a so-called "supervolcano" - a huge, geologically active feature that is "hundreds of times bigger than Mount St. Helens," according to Robert Smith, a professor of geophysics at the University of Utah who co-wrote the study. The caldera, or crater, in which it is situated formed when the "supervolcano"'s cone fell apart during an eruption 640,000 years ago.Although the "supervolcano" has produced 30 smaller eruptions since then, Smith doesn't believe there is any evidence for an imminent eruption or "hydrothermal explosion". The park's rise - the result of magma and hydrothermal fluids piling up below the volcano - is part of a natural cycle common to caldera. "Since … about 14,000 years ago, the Yellowstone caldera has inflated and deflated about six to eight times without a volcanic eruption," said Kenneth Pierce of the U.S. Geological Survey.
What's unclear is when the "supervolcano" might next "burp," as Smith puts it. Predicting such an event is extremely difficult because the high-tech, precise equipment needed to monitor conditions has only been around for a few years. Assuming it doesn't erupt in the immediate future, Smith and Pierce expect the advent of new GPS and satellite technologies to eventually make the prediction game much easier and, most importantly, much more accurate.
Via ::National Geographic News: Yellowstone Is Rising on Swollen "Supervolcano" (news website)