Steamboat residents who thought they experienced their second earthquake in 10 days Sunday night weren't dreaming.
John Minsch with the USGS National Earthquake Information Center in Golden confirmed a "micro earthquake" took place at about 10:18 p.m. Sunday. The epicenter was 8 miles northeast of Steamboat. Like the last quake, this one was centered about 3 miles below the earth's surface. Sunday night's epicenter was on the west side of the Continental Divide, just north of Soda Creek.
It was a magnitude 2.2 quake, smaller than the 4.1 temblor that shook homes and made saltshakers dance on kitchen tabletops in Steamboat just before midnight Sept. 30.
Sunday night's quake was detected by sensitive equipment at the USGS that plots earthquakes all over the globe. However, it didn't cross a threshold that automatically results in a quake being plotted on the USGS Web page.
"The computer detected the P-wave (shock wave) on equipment at Idaho Springs, Snowmass and another place in Wyoming," Minsch said. "It didn't get enough data to automatically report a location."
Minsch discounted the possibility that the second quake was an aftershock of the first quake. He said there were no conclusions to be drawn from a second quake felt in Steamboat in a relatively short time span.
"The first earthquake was not really large enough to have an aftershock," Minsch said. "This one (Sunday night) was real small. It's not unlikely that people felt it. But we probably have earthquakes of this size quite often in areas where people don't feel it."
The Sept. 30 quake prompted 180 calls to the county's 911 center in the first hour after it shook homes. Many people reported thinking an automobile had struck their homes. That didn't happen Sunday night, according to a spokeswoman at the Routt County Communications Center.
More than a dozen people contacted the newspaper to inquire about the Sunday night microquake.
Before the 4.1 quake in September, the last widely noticed earthquake was in February 2000, when 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 Sept. 30 quake was 14 miles east-northeast of Steamboat. The epicenter was on the other side of the Continental Divided, near the eastern foot of Buffalo Pass.