ROCKINGHAM — Some residents of Richmond County reported feeling tremors Sunday morning from an earthquake about 130 miles away from the epicenter.
According to the U.S. Geologic Survey, a 5.1 magnitude earthquake struck near the town of Sparta in Alleghany County, just south of the Virginia border, around 8:07 a.m.
The quake, the USGS reports, was a result of “oblique-reverse faulting in the upper crust of the North American plate” about 2.3 miles down. Sparta’s elevation is nearly 3,000 feet above sea level.
“Focal mechanism solutions for the event indicate rupture occurred on a moderately dipping fault either striking to the northwest or south,” reads the Tectonic Summary. “This earthquake occurred in the interior of the North American plate. Such mid-plate earthquakes are known as intraplate earthquakes and are generally less common than interplate earthquakes that happen near tectonic plate boundaries.”
The USGS reports that four foreshocks ranging from 2.1-2.6 were felt within 25 hours of the quake.
The earthquake created quite the social media buzz Sunday with residents in Rockingham, Ellerbe and Hamlet reporting they felt the shaking, while said they did not.
According to a map, the quake was felt along the North Carolina coastline from Wilmington to Cape Hatteras; as far south as Atlanta, Georgia; as far west as Chattanooga and Knoxville, Tennessee; and as far north as Baltimore, Maryland.
There are also tremor reports in eastern Kentucky, West Virginia, southwestern Pennsylvania and southeastern Ohio.
Will there be any aftershocks?
Seismologists predict a 48% chance of up to aftershocks of a magnitude 3.0 or higher within the next week: “… such earthquakes may occur in the case that the sequence is re-invigorated by a larger aftershock.”
The probability for anything as high or higher than the Sparta tremor is very low.
The USGS says large earthquakes are “relatively uncommon” for this area of the country.
“Moderately damaging earthquakes strike the inland Carolinas every few decades, and smaller earthquakes are felt about once each year or two,” the Tectonic Summary reads.
The largest earthquake recorded within 65 miles of the Sparta quake in the 20th century was a 5.2 in the Great Smoky Mountains in 1916, according to the USGS. A 5.8 hit Mineral, Virginia, in 2011 and was reportedly felt all over the East Coast.
A report shows there were two small earthquakes — a 2.4 and a 2.6 — reported nearly an hour apart on Aug. 3, between Knoxville and Pigeon Forge in Tennessee; and a 2.1 was felt northeast of Knoxville on July 30. A 2.4 magnitude tremor was also felt July 30 near Huntersville, West Virginia, close to the Virginia border, nearly 50 miles north of Roanoke, Virginia.
The USGS reported a 2.2 magnitude quake in South Carolina, between Camden and Kershaw, on July 25.