Snowmass home to new seismic station
July 26, 2005
From now on, when the earth shakes beneath Snowmass Ski Area, the National Earthquake Information Center is going to know all about it.A seismic station was installed on top of Snowmass Ski Area on June 30 as part of the U.S. Advanced National Seismic System. Information gathered there travels via satellite link to the earthquake information center in Golden, Colo.The project is a joint effort between the U.S. Geological Survey and the University of Colorado at Boulder.
“It covers a gap in our coverage – to locate earthquakes we usually use a triangular pattern, with three stations surrounding the quake,” said Anne Sheehan, an associate professor at CU Boulder’s department of geological sciences and project coordinator for the new seismic station. “Right now in Colorado we have stations in Idaho Springs and Great Sand Dunes National Monument (near Mosca.) There’s one in eastern Kansas that’s helpful, and in Utah and Wyoming.”Already, the station detected a magnitude 2.8 mining-induced earthquake near Paonia on July 7. Mining-induced earthquakes normally occur when a support system in an old mine gives way and collapses. It’s the earth settling in response to activity in the mines, she said.The station in Snowmass may be able to help geologists solve the mystery of why the Aspen area is occasionally affected by small earthquakes. Sheehan said it is unknown if the occasional earth movement in this area is a result of old mines in the mountains around Aspen.
Colorado’s largest recorded earthquake happened near Ridgway in 1960 and was a magnitude 5.5. Such a large earthquake is “very unlikely” to have been mining induced, Sheehan said.”By studying these, we’ll get a better handle on them and figure out which are tectonic (caused by movement of the earth’s plates) and which aren’t,” she said. “Colorado is pretty well known for human-caused earthquakes.”A number of earthquakes occurred in Denver near the Rocky Mountain Arsenal in the 1960s, where waste fluids were injected into the ground at a chemical weapons plant.
As for naturally caused earthquakes, the biggest fault line in the state is near the Great Sand Dunes of the San Luis Valley. The fault is an extension of the Rio Grande Rift, a volcanic zones that passes through New Mexico.The seismic station in Snowmass consists of a seismometer that measures ground motion, a digitizer that records data and a satellite dish. The station is powered by car batteries that are recharged by solar panels.Funding for the station was provided by the National Science Foundation, and installation costs were paid for by the USGS. The Snowmass station is the first to be run cooperatively between CU Boulder and the USGS.Naomi Havlen’s e-mail address is firstname.lastname@example.org