Updated May 1, 2008 at midnight
Routt County Most residents of the Yampa Valley were asleep in bed Wednesday morning when a small earthquake rumbled three miles underground about three miles southwest of Steamboat Springs.
The U.S. Geological Service measured a magnitude 2.8 quake at 4:19 a.m. in the rural area outside city limits, located with a broad margin of error. For GPS owners, the quake was centered at 40.453 degrees north and 106.871 degrees west.
Susan Potter, a geophysicist with the U.S. Geological Service based in Golden, said that at 3.1 miles beneath the earth's surface, the quake was relatively shallow.
"The fact that it was shallow meant there was a little bit more of a chance it might have been noticed," Potter said.
The USGS gathers citizen reports of earthquakes at its Web page, but Potter said no comments about the Steamboat quake had been reported as of mid-afternoon.
The last earthquake strong enough to be felt by Steamboat residents occurred just before midnight on Oct. 9, 2005. It was just a 2.2 on the scale. Steamboat residents were attuned to the earth shaking that night because just 10 days earlier, the valley was shaken by a 4.4 magnitude quake.
The larger quake was centered on the east side of Buffalo Pass. The smaller was on the Steamboat side of the pass, just north of Soda Creek.
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 an automobile had struck their homes.
Before the 4.4 quake Sept. 30, 2005, the last widely noticed earthquake was in February 2000. On that day, a 3.0 quake resulted in a loud "boom" on Steamboat's west side. People at the public schools in Strawberry Park reported seeing a wavelike motion in the floor of the schools' arcade. The epicenter of that quake was in the Mount Zirkel Wilderness Area south of Wolverine Lake.
The biggest earthquake to hit the Steamboat area in modern times was observed in February 1955.
"Firsthand accounts suggest the quake was strong enough to crack the plaster of many homes and shake dishes from tabletops," Vince Matthews, the state geologist and director of the Colorado Geological Survey told the Steamboat Today.
Since 1895, 13 earthquakes of magnitude 2.2 or larger have originated on faults found throughout Routt County, according to the Colorado Geological Survey. Three other quakes ranging in magnitude from 3.0 to 3.9 have originated just outside county boundaries: two in Jackson County and one in extreme northern Garfield County.
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