Small earthquake reported Saturday near Steamboat |

Small earthquake reported Saturday near Steamboat

Pilot & Today staff

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■ Oct. 10, 2005: A whole lot of shaking going on

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— A magnitude-2.5 earthquake hit Routt County at 3:46 a.m. Saturday.

According to the U.S. Geological Survey, the earthquake happened 12 miles west/southwest of Steamboat Springs at a depth of 3.1 miles.

An earthquake of magnitude 2 is the smallest typically felt by people, and a magnitude of 5 or more is potentially damaging, according to the USGS.

The most recent earthquake in Routt County was a magnitude-2.8 quake at 6:19 a.m. March 30. That quake happened 15 miles south/southwest of Howelsen Hill at a depth of about 0.6 miles. No one reported feeling that earthquake.

The March earthquake coincided with an accident at Twentymile Mine that shut down longwall mining operations into late April.

Peabody Energy Denver Administration District Manager Allyn Davis said April 27 that the accident involved the "compression" of coal pillars that are relied upon to support the ceiling of the underground mine. At the same time the pillars compressed, a roof fall took place, partially blocking the tail end of the longwall, which serves as an exit point for miners.

State geologist Vince Matthews said in March that he contacted the mine after surmising that the earthquake could have been triggered by mining activity. He also said the number of geologic faults that cut across the area suggest that a natural earthquake is possible.

Davis said that although mine-induced seismic activity is a well-known phenomenon, the technology does not exist to positively tie the two events together.

The last earthquake strong enough to be felt by Steamboat residents happened just before midnight Oct. 9, 2005. It had a magnitude of just 2.2, but Steamboat residents were attuned to the earth shaking that night because just 10 days earlier, the valley was shaken by a magnitude-4.4 quake. The Sept. 30, 2005, quake prompted 180 calls to the county's 911 center in the first hour after it shook buildings. Many people reported thinking a car had struck their homes. Before that quake, the last widely noticed earthquake was in February 2000.

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