Earthquake Swarm Rumbles Yellowstone

Posted by: Madame Fleur

Jan. 13, 2008

Since December 26, a swarm of roughly 900 earthquakes have growled through the Yellowstone Lake area of Yellowstone National Park (“Yellowstone”).  America’s first national park experiences hundreds of earthquakes each year and swarms are not unusual.  Even so, the recent swarm was unusually energetic.  Seismologists predict that the earthquakes will likely continue and may increase in intensity.

Yellowstone is beloved by visitors as home to the world’s most abundant thermo-geologic features, namely its steam vents, hot springs and active geysers.  These features occur because the park sits upon one of the earth’s largest volcanoes – grimly deemed a “super volcano.”  Such volcanoes are not towering cones; they are trapped in underground depressions, where thermal pressure has difficulty escaping.  This buildup of pressure is responsible for both the beautiful thermal features of the park, as well as the frightening risk of a cataclysmic eruption.

In the ancient past, Yellowstone ’s volcano erupted 2,500 times more powerfully than Mount St. Helens’ 1980 blast, hurling ash as far away as Louisiana .  Thankfully, no eruption as large has occurred while humans have walked the earth; the most recent Yellowstone eruption occurred nearly 640,000 years ago.  Even so, Yellowstone is accumulating a massive reservoir of subterranean magma, and scientists have recently gauged significant changes in the magma chamber’s pressure.

The recent swarm of activity has some observers portending imminent catastrophe, but geologists dismiss the threat as overstated.  For starters, the earthquakes were small: the largest registered a Richter scale magnitude of 3.9, with most activity registering between 2 and 3.  Furthermore, the quakes were centered on the east side of the Yellowstone Caldera, an area closely monitored by geologists for its historic earthquake activity (a “caldera” is defined as a volcanic crater that has a diameter many times that of the vent and is formed by collapse of the central part of a volcano or by explosions of extraordinary violence). 

The natural beauty of today’s Yellowstone was created in part by ancient forces of massive effect.  Will such forces appear in the near future?  Scientists tend to agree that it isn’t likely.  "Statistically, it would be surprising to see an eruption the next hundred years," said Jake Lowenstern, head of the Yellowstone Volcano Observatory. 

This sentiment was echoed by Robert Clayton, a geology professor at Brigham Young University who has been monitoring the quake activity with his university’s seismograph machine: "An eruption in Yellowstone and anywhere else won't sneak up on us.  Eruptions give lots of warning signs, and we've gotten good at reading those signs. So, just having a swarm of earthquakes by itself isn't something to be alarmed about."  And that means we're safe...hopefully.