A magnitude 3.8 earthquake struck northern New Mexico at 12:40 a.m. Monday, about 11 miles south of the Colorado state line, according to the U.S. Geological Survey. It is the fourth earthquake of that magnitude in the same border area since June 20.

The USGS places the epicenter at a depth of about 3 miles (5 kilometers), roughly 19 miles (31 kilometers) south of Segundo, Colorado — the nearest community the agency lists, which is why the quake appears in USGS listings under a Colorado place name even though the epicenter itself lies in New Mexico. It was about 21 miles (34 kilometers) from Raton, New Mexico, and 28 miles (46 kilometers) from Trinidad.

Two people filed “Did You Feel It?” reports with the USGS, the highest of them describing weak shaking. The agency's ShakeMap for the quake estimates peak shaking of about 4.8 on the Modified Mercalli intensity scale near the epicenter — the range in which shaking is commonly felt indoors and dishes and windows may rattle. No injuries or damage have been reported.

Four quakes of the same size in five weeks

The overnight quake is the latest in a run of activity along the Colorado–New Mexico border. Since May 25, the USGS catalog lists 30 earthquakes in the area bounded roughly by Walsenburg, the Kansas line, Cimarron and the Sangre de Cristos — 15 on each side of the state line. The Press reported on three of them on June 20.

Four have registered magnitude 3.8. The first, on June 20 at 11:32 a.m., was centered about 10 miles south-southeast of Stonewall Gap, Colorado, and drew four felt reports. Two more came within ten minutes of each other early on July 6 — one at 3:21 a.m. about 21 miles south-southwest of Segundo, which drew eight felt reports, and one at 3:31 a.m. about 19 miles south of Segundo. Monday's is the fourth.

Between them the catalog shows a magnitude 3.1 on June 25, a 2.9 on June 20 and a 2.8 on July 2, along with a series of smaller events clustered on the same few days. The activity has centered on two areas: one around Stonewall Gap and Weston in Las Animas County, Colorado, and one south of Segundo across the line in New Mexico.

An active basin, and a busier year than the last two

The area is the Raton Basin, a coal- and gas-bearing region straddling the state line west of Trinidad. It is among the more seismically active places in either state. The USGS catalog lists 451 earthquakes of magnitude 2.5 or greater there since 1990.

By that measure 2026 is already a busier year than the previous two. The catalog shows 24 quakes of magnitude 2.5 or greater in the basin so far this year, against 13 in all of 2024 and 10 in all of 2025. It is not a record: 2023 produced 45 and 2011 produced 44.

The largest earthquake in the basin in the USGS record since 1990 was a magnitude 5.3 on August 23, 2011, centered south of Valdez, Colorado. A magnitude 5.0 struck south of Weston in August 2005, and a magnitude 4.3 near Segundo in March 2023 — an episode the Press also covered.

Why the basin shakes

Research has connected the basin's earthquakes to the underground injection of wastewater produced alongside natural gas. A 2014 study in the Bulletin of the Seismological Society of America, by USGS researchers Justin Rubinstein, William Ellsworth, Arthur McGarr and Harley Benz, examined the sequence directly; its title describes the activity from 2001 onward as an induced earthquake sequence in the Raton Basin of northern New Mexico and southern Colorado.

The USGS has not published a statement attributing Monday's earthquake specifically to any cause, and this report does not do so either.

Did you feel it?

The USGS asks anyone who feels an earthquake to file a “Did You Feel It?” report at earthquake.usgs.gov, which the agency uses to map how far shaking was felt — reports from rural areas are particularly useful because there are few instruments nearby. Details on this quake and any that follow are posted on the same site.