Western and southern Colorado were shaken early Friday by three earthquakes, the largest hitting 4.3 on the Richter scale.
The first quake was reported about 2 a.m. roughly 24 miles west-southwest of Trinidad. It measured 3.2 on the Richter scale, the U.S. Geological Survey reported.
Two hours later, the biggest Colorado earthquake this year was reported 28 miles northwest of Parachute. A second tremor measuring 2.9 shook the same area 1½ hours later.
Colorado has recorded 525 earthquakes since 1973, most of them at 2 to 3.5 on the Richter scale, a USGS map shows.
On May 17, 1973, officials reported a 5.4 earthquake after an underground nuclear test about 36 miles northwest of Rifle.
The largest nonhuman- caused earthquake in that time was a 5.3 quake Aug. 23, 2011, near Trinidad.