Three small earthquakes rattled the southern Colorado mountains in Las Animas County Saturday, with the largest registering magnitude 3.8, according to the U.S. Geological Survey.

The strongest of the three struck at 11:32 a.m. about 9 miles (14 kilometers) south-southeast of Stonewall Gap at a depth of roughly 4 miles (6.6 kilometers). The USGS recorded it as a magnitude 3.8 event, and at least three people reported feeling the shaking. The agency generated a ShakeMap for the quake, indicating light shaking was possible in the immediate area.

A second, smaller quake followed at 12:15 p.m., measuring magnitude 2.4 and centered about 10 miles (16 kilometers) southwest of Weston at a depth of roughly 5 miles (8.4 kilometers).

The third struck at 3:04 p.m., a magnitude 2.9 event located about 9 miles (15 kilometers) south-southeast of Stonewall Gap at a depth of about 3 miles (5 kilometers). One person reported feeling it.

No injuries or damage were reported. Earthquakes in the magnitude 2 to 3 range are often felt by people close to the epicenter but rarely cause damage, while a magnitude 3.8 quake may be felt more widely as a brief jolt or rumble.

The quakes were centered in the Raton Basin, a coal- and gas-rich region straddling the Colorado-New Mexico line west of Trinidad that has become one of the most seismically active areas in the state. The USGS notes that the basin has seen a marked rise in earthquakes since the early 2000s.

Scientists have linked that increase to the underground injection of wastewater produced as a byproduct of natural gas extraction. As Colorado Newsline reported after a 2023 swarm in the same area, USGS research geophysicist Justin Rubinstein said, “I think it’s highly likely that these earthquakes were induced by the wastewater disposal operations in the area.”

A 2014 USGS study, of which Rubinstein was the lead author, found that wastewater injection was responsible for inducing the majority of the basin's seismicity over the previous 13 years. Colorado's most powerful earthquake in half a century — a magnitude 5.3 event southwest of Trinidad in 2011 — was also tied by USGS research to fluid injection.

The USGS encourages anyone who feels an earthquake to file a “Did You Feel It?” report at earthquake.usgs.gov, which helps the agency map the extent of shaking. Details on each of Saturday's quakes are available on the USGS earthquake website.