The strongest earthquake to hit Colorado in more than four decades startled thousands of residents along the New Mexico border as it toppled chimneys, cracked walls and triggered minor rockslides in the arid, mountainous region. No injuries were reported Tuesday.
Monday night's magnitude-5.3 earthquake struck just hours before a magnitude-5.8 temblor in Virginia _ also rare for that area _ shook much of Washington, D.C., and the East Coast.
Small aftershocks rattled the region about 180 miles south of Denver but caused no further damage.
"This was the first time you could see the fear in people's eyes," said Dean Moltrer, 39, who with his brother Ray owns the Big 4 Country Store in Valdez, a former coal mining town of about 100 people in Colorado's Picketwire Valley.
"Your family looks to dad to figure out what to do," chimed in Ray Moltrer. "Dad didn't know what to do. Dad was scared for his life."
The quake hit at 11:46 p.m. MDT Monday about nine miles southwest of Trinidad, according to the U.S. Geological Survey's National Earthquake Information Center in Golden. It had an estimated depth of 2.5 miles and was felt in a relatively large area of southern Colorado and northern New Mexico.
The earthquake was the largest in Colorado since a magnitude-5.3 temblor was recorded in Denver's northern suburbs in 1967, said Paul Earle of the USGS.
Las Animas County Sheriff Jim Casias said Colorado authorities were assessing damage that included a porch collapse and a partially collapsed roof.
In Segundo, a tiny town a mile west of Valdez, the brick facade of a historic building lay in a pile. Nearby, daylight peered through a crack in the wall of Ringo's Super Trading Post, where owner Gary Ringo said he lost thousands of dollars' worth of liquor and soda.
Dozens of residents in Trinidad, a town of 9,000 people, and in northern New Mexico called the USGS to report the shaking. Others called from Colorado Springs and as far away as southwestern Nebraska, said Gavin Hayes, a USGS research seismologist.
In New Mexico, the town of Raton _ already hit this summer by fire and flooding _ was abuzz about Monday's quakes, which included a smaller foreshock at about 5:30 p.m.
"It was shaking first, like you were in a vibrating bed. Then there was a rolling effect and then there was shaking again," said Barbara Riley, owner of the Heart's Desire Bed and Breakfast.
Riley, a teacher, said she'll likely have to fill in cracks at her 100-year-old home.
Minor rockslides were reported on Colorado Highway 12, which follows the Purgatoire River, and along Interstate 25, but both highways remained open. A road grader trolled the side of Highway 12 clearing out small rocks.
Ron Thompson, mine manager with New Elk Mine about 30 miles west of Trinidad, said coal miners 300 to 800 feet underground didn't feel anything. But he said crews above ground and at the company office in Trinidad, where he was at the time, did.
"Not real exciting, but it got your attention," Thompson said.
Small aftershocks continued in a region that the USGS says is not known for major quakes or active faults. About a dozen small temblors were recorded in the area in August and September 2001, said USGS geophysicist Jessica Sigala.
Hayes said the quake likely was a rare product of interaction between the Eastern Shield _ ancient rock east of the Rocky Mountains _ and the newer formations of the Rocky Mountain range. Such quakes can be felt at greater distances because the underlying bedrock doesn't absorb energy the way more seismically active areas such as California do, he said.
Colorado is no stranger to earthquakes, but most are small and go unnoticed.
According to the USGS, an 1882 earthquake near what is now Rocky Mountain National Park is believed to be the largest recorded in the state, with an estimated magnitude of 6.6.
Associated Press writers Susan Montoya Bryan in Albuquerque and Steven K. Paulson in Denver contributed to this report.