WASHINGTON A 5.3 magnitude earthquake, the biggest in the state in some four decades, shook Colorado late on Monday in an area of the United States where quakes are rare, the U.S. Geological Survey said on Tuesday.
The quake struck at 11:46 p.m. Monday night 180 miles south of Denver and 20 miles northwest of Raton, New Mexico, at a depth of 2.5 miles.
Area media reported minor damage to some homes but no injuries or deaths.
"It's a seismically active area so it's not unheard of that you would have an earthquake in this area," USGS National Earthquake Information Center geophysicist Julie Dutton told Reuters Tuesday morning from Golden, Colorado. "But to have a 5.3 anywhere in Colorado, let alone in this area, is rare."
The quake had triggered 1,107 reports from people who felt the shaking as of mid-morning.
The last Colorado quake -- discounting an event linked to an underground nuclear test in 1973 -- to measure at least 5.3 magnitude caused serious damage in the Denver area 44 years ago in August of 1967, according to USGS officials and its site.
Monday's quake is rare in the area of the United States east of the Rocky Mountains known as the "Stable Continental Region."
"Most of the enormous region from the Rockies to the Atlantic can go years without an earthquake large enough to be felt," the USGS wrote in its summary of Monday's seismic activity, "and several U.S. states have never reported a damaging earthquake."
The Monday quake was felt as far north as Fort Collins, Colorado, some 261 miles from the epicenter, according to the USGS "Did You Feel It?" map, a real-time accumulation of data from local shaking and damage reports.
Though earthquakes east of the Rockies are less frequent than in the West, they can be felt over an area as much as 10 times larger than a quake of similar size on the West Coast.
Dutton noted that the earthquake's history within 40 km of the main shock shows that roughly 80 earthquakes of magnitude 2.0 or more have occurred since 2000.
"So it definitely rumbles down there," she said, "But like I said - 5.3 magnitude is the largest in a long time."
(Editing by Jerry Norton)