COLUMBUS, Ohio (WCMH) -- Several minor earthquakes were recorded in southeastern Ohio last week.
A magnitude 3.1 earthquake, with an epicenter 3 miles north-northwest of Oak Hill in the southern part of Jackson County, occurred on Feb. 3, according to the U.S. Geological Survey. The depth of the earthquake was a 16 miles below the surface.
The tremor was felt most strongly around Portsmouth, Ohio, and Huntington, West Virginia, and as far north as New Albany and the Columbus area around 4:05 p.m. Small seismic activity occurred both before and after the minor earthquake, though below the level of reporting.
The USGS recorded a second earthquake on Feb. 3 near Marietta in Washington County a little before 6 p.m., centered 1.5 miles north-northeast of Reno near the West Virginia border. The earthquake registered 2.8 and occurred at a depth of 6 miles. The same area experienced two minor quakes (2.0-2.1 magnitude) early on Jan. 29, with an epicenter five miles east of Marietta, and a depth of 5 miles.
Brendan Crowell, assistant professor at the School of Earth Sciences at Ohio State University, said, "The earthquake is roughly 6-10 miles north of the unnamed fault in Scioto County. It's not uncommon for deep events to be on unmapped faults; the existence of a surface feature would imply that deeper structures are likely."
Earthquakes less than magnitude 3 often go unnoticed and are detected by a seismometer. However, on Dec. 16, 2024, a magnitude 3.3 earthquake, centered 2 miles northwest of Chesapeake in Lawrence County, created some noticeable shaking.
The region where the Washington County quakes occurred has a known fault, called the Ohio River Fault, that lies within the Rome Trough Fault System. The faults run deep below Earth's surface and are very old, forming during a period when the Appalachians formed and Earth's upper crust was compressed 250 to 300 million years ago, and when the continental crust was pulled apart about 200 million years ago.
Subtle movement of the North American plate along existing fault lines likely triggered the recent quakes, as strain is released. Seafloor spreading along the Mid-Atlantic Ridge, an underwater mountain range along the floor of the Atlantic Ocean, results in a west-southwestward drift of the North American plate away from Europe and Africa.
The Ohio Division of Natural Resources (ODNR) Division of Geological Survey maintains a network of 29 seismograph stations around Ohio to constantly monitor earthquake activity. The Ohio Seismic Network was put in place in January 1999 to keep track of activity around the clock, providing the location and magnitude of earthquakes.