CU-Boulder Student Detects Earthquakes Near Boulder

March 19, 1997

A University of Colorado at Boulder geology student detected 23 small earthquakes within a 50-mile radius of Boulder during a three-month period last fall.

The earthquakes ranged from magnitude 0.5 to 2.0 on the Richter scale. The smallest earthquake a person is able to feel is about magnitude 3, and a quake of 3.5 can cause slight damage.

Noah Hughes, 23, of Riverbank, Calif., will present his findings March 20 at a section meeting of the Geological Society of America in El Paso, Texas. The project was part of a new class on field geophysics taught by Anne Sheehan, assistant professor of geological sciences and co-author of the study. Sheehan also is a fellow of the Cooperative Institute for Research in Environmental Sciences.

The quakes were detected by a three-station, solar-powered seismic network set up by the class. One station was seven miles west of downtown Boulder on Sugarloaf Mountain, one was six miles north of downtown on Table Mountain and one was near Louisville, east of Boulder.

Epicenter locations were determined for each quake and a map of the seismic

activity was created. The most quake activity was recorded northwest of Golden, said Hughes, a senior who will graduate in May.

However, "I don't think people need to worry about anything big happening around here anytime soon," he added.

Although seismic activity along Colorado's Front Range has been relatively quiet this century, there is evidence of past tectonic activity, Sheehan said. An earthquake estimated at 6.6 magnitude struck north-central Colorado in 1882.

"The results help give us an idea about levels of seismicity in the region that have implications for earthquake hazard assessments," she said. "The locations of the earthquakes also help us map out active faults."

Earthquakes in the Boulder area have been studied very little, Sheehan said. In addition to earthquake seismology, members of the 13-student field geophysics class did subsurface imaging of groundwater supplies, soil and rock structure, archaeology sites, volcanic features and Louisville's old mine shafts.

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