A series of noisy rumblings in Lincoln County turned out to be a 2.5 magnitude earthquake, according to the U.S. Geologic Survey.
Authorities received numerous calls after the noisy booms were heard in several areas around 6:30 p.m. Thursday, but no damage was reported.
The epicenter of the quake was four miles south of Lincolnton near Thurmond Lake's Little River arm.
Earthquakes are known to occur periodically in the Augusta-Columbia County area, which lies along the Fall Line where the coastal plain meets the Piedmont region.
For decades, scientists have monitored the region around the U.S. Army Corps of Engineers' earth-and-concrete Thurmond Dam for seismic activity that has included dozens of small quakes.
According to the National Earthquake Information Center in Golden, Colo., Thurmond Lake is one of the major earthquake centers in Georgia and South Carolina, where pressure changes caused by water in huge reservoirs can activate seismic activity.
The Corps routinely reinspects Thurmond Dam after even very minor earthquakes and maintains seismic detectors throughout the dam.
Seismic activity is frequently studied in the Thurmond Lake area - including Lincoln County - where a formation known as the Eastern Piedmont Fault System runs from the Alabama-Georgia border through South Carolina, bisecting the 70,000-acre reservoir.
The largest recent quake in the lake area occurred Aug. 2, 1974, and registered 4.2. Monday's small quake is comparable to three recorded in nearby Edgefield County, S.C., in 1996, which measured 2.5, 2.3 and 2.2 in magnitude.
Experts say Augusta is unlikely to experience a serious quake. The only major quake in the Southeast occurred in 1886 in Charleston, S.C., claiming 110 lives.