A magnitude 4.8 earthquake rattled Yellowstone National Park in Wyoming on Sunday near the Montana border, according to the U.S. Geological Survey. Several aftershocks with a magnitude over 3 were also recorded.
USGS Yellowstone Volcano Observatory spokesman Peter Cervelli noted that the epicenter of the quake was situated in the middle of park, near the Norris Geyser Basin. Cervilli added that no damage was reported, and that there were not many visitors during the time of the event.
The park sits atop of the Yellowstone Caldera, sometimes called the Yellowstone Supervolcano, a volcanic caldera. Seismic activity is commonplace in the region, and the Yellowstone Caldera sees between 1000 and 2000 measurable earthquakes a year, though most register a magnitude 3 or less. On occasion, a flurry of earthquakes is detected in rapid succession, an event called an earthquake swarm.
Here's some information on the caldera:
Cervilli pointed out that Sunday's quake, which occurred at 12:34 am GMT, will likely generate more secondary shockwaves in addition to the three already recorded, though noted that volcanic activity isn't expected. Yet, Sunday's earthquake was the most powerful recorded in the park since 1985, when seismologists logged 3,000 events up to magnitude 4.9 during a three-month period.
The last major eruption of the Yellowstone Supervolcano was the Lava Creek event which occurred 640,000 years ago, which ejected approximately 240 cubic miles of pyroclastic detritus into the air. A repeat of an eruption of that magnitude today might render a large portion of the western United States uninhabitable for at least a decade.
Geologists have closely monitored the rise of the Yellowstone Plateau, which has seen an accelerated upward movement of almost 3 inches per year between 2004 and 2008. This rise is indicative of an increase in magma chamber pressure. Seismologist Robert B. Smith, lead author of the study and professor of geophysics at the University of Utah, commented,"Our best evidence is that the crustal magma chamber is filling with molten rock. 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."
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