Earthquake Swarm at Yellowstone National Park

Seismographs Record New Activity in the Caldera

Jan 5, 2009

Yellowstone caldera is the home of Yellowstone National Park, the oldest park in the U.S. National Parks System. Visitors come to this park every year to witness the exciting natural process that are evidence of the geologic activities that have shaped this park - geysers, hot springs, fumaroles and boiling mud ponds heated by a massive magma chamber, or hot spot, below the crust. The park itself sits on top of numerous layers of welded ash deposits, some more than 400 meters thick - a record of an active and explosive volcanic past.

New seismic activity in the park has scientists wondering what this supervolcano has in store for the future. The activity is being monitored by the University of Utah Seismic Network which, along with the National Park Service and the U.S. Geological Survey, makes up the Yellowstone Volcano Observatory.

Earthquakes In Yellowstone

According to the Yellowstone Volcano Observatory (YVO), over 500 earthquakes have been recorded by seismographs since December 27, 2008. This increase in activity is being called an "earthquake swarm" by geologists studying this active volcano. Earthquakes near an active volcano are common, and normally seismographs stationed around Yellowstone will record between 1,000 to 2,000 earthquakes a year. However, this latest swarm of 500 earthquakes within about a week has the attention of scientists. YVO reports that the earthquake swarm is, "the most intense in this area for some years and is centered on the east side of the Yellowstone caldera."

So far, the strongest earthquake recorded was a magnitude 3.9 at the onset of the swarm. This quake and subsequent others were felt by visitors and residents of the park. Scientists from YVO have also been able to calculate from seismic data that the earthquakes are occurring at depths ranging from 1 km to about 10 km beneath the surface; they have not yet been able to attribute any of the earthquakes to fault activity. However, when magma rises, the subsequent heating and breaking of rock causes earthquake swarms like the ones recorded at Yellowstone.

Future Eruptions of Yellowstone Caldera

Although park rangers and geologists are monitoring this new activity very closely, there are no concerns that Yellowstone will erupt anytime in the near future the way it did 642,000 years ago when there was a VEI 8 eruption. This eruption deposited a layer of ash over the western half of the United States and was the inspiration for the Discovery Channel/BBC co-production Supervolcano. Although an eruption of this magnitude is not likely without more obvious signs of activity, YVO scientists do think it is possible that a smaller eruption, more comparable to smaller volcanoes around the world, could happen.

Currently, YVO's Volcano Alert Level is normal, meaning that there is no concern for an eruption; and the Aviation Color Code is green, meaning that aircraft in the area do not need to worry about volcanic ash clouds. Any changes that occur within the caldera will be immediately detected by the robust instrument network operated by YVO. If there is need for concern, park rangers and local officials will be notified immediately.

The copyright of the article Earthquake Swarm at Yellowstone National Park in Volcanology is owned by Alexandra Matiella Novak. Permission to republish Earthquake Swarm at Yellowstone National Park in print or online must be granted by the author in writing.

Jan 6, 2009 10:19 PM

Guest :

the Northridge and japan quake anniversarries are coming up next week
Here in So. California it seems we get a pretty good jolt an average of every 15 years or so. Its been quiet here for a while, Could this be a sign of things to come here?
I remember watching a show on how old faithfulls eruption times seem to change before an earthquake. Is there any signs of that happening/

Jan 7, 2009 9:17 AM

Alexandra Matiella Novak :

It is very difficult to conclusively relate the eruption intervals of the Old Faithful geyser with quake activity in California. I'm not sure when you saw the show you mention, but a published article in Geotimes suggests that the eruption interval is related to precipitation trends (http://www.geotimes.org/aug08/article.html?id=nn_oldfaithful.html).
It's also difficult to day that earthquake activity, in general, has consistent intervals. Earthquakes are probably the most unpredictable geologic or natural hazard process in the bunch. In CA, there's a few everyday, although most go unnoticed (http://quake.usgs.gov/recenteqs/). Energy and resources would be much better spent on earthquake-proofing structures and community preparedness then on trying to predict when or how strong one will be.