Utah Earthquakes Leading up to Volcanic Action

Large earthquakes — above 4 on the Richter Scale — are occurring in Utah at about a normal rate, but geologists say it seems much higher.

Thursday evening's quake on the Utah/Wyoming border is number 27 so far this year in Utah. That one near Randolph was one of the strongest in the state in 75 years, according to seismic station reports, the U.S. Geological Survey and professional quake watchers.

Although there was little to no damage Thursday at the surface of the epicenter, some 77 miles northeast of Salt Lake City, that doesn't mean that it wasn't geologically significant. If the current pace continues, more than 90 significant earthquakes will occur by the end of the year.

Between April of last year and now, there were 80 large earthquakes, according to the USGS, which is quick to point out quakes are just part of the natural give and take in the supporting land mass miles below Utah's surface.

Whenever there is a seismic event in the Mountain West, it's a pretty good bet the Yellowstone National Park caldera is involved. It is a still-active volcano and massive slab of fractured fault-split of land centered in Wyoming.

It is one of the most volatile sections of land in the western hemisphere, and seismic activity there has been so common in the past two years, scientists are wondering if quakes like the one Thursday are portending "the big one" of a different sort — not a massive earthquake, but a volcanic eruption in Yellowstone that would make the Mt. St.Helens's eruption in Washington look like a a postprandial burp.

Scientists believe the crust beneath Yellowstone is highly fractured, and that the stress of other recent earthquakes on the region is a cogent warning of devastating shifts to come.

"So, we're getting stress release in these earthquakes and displacement of just millimeters," said Robert Smith, a geophysicist at the University of Utah. The earth is always in motion and plates slip and shift under the constant pressure deep below the surface, said Smith. What is causing the recent spate of seismic shudders can't be known, he said, but he believes they might be spawned by magma building up just below the surface of the land. So, along with fueling the famous geysers, it may be setting off tremors throughout the region.




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