A preliminary 5.1-magnitude earthquake occurred near Sparta, in northwestern North Carolina, at 8:07 a.m. Sunday, close to the Virginia border. The quake rattled the Carolina Piedmont but was reportedly felt as far away as Atlanta, part of Tennessee, Washington and Ohio.
There were some reports of minor damage in the vicinity of Sparta, including of items tossed off shelves at a grocery market and belongings shaken off their perches atop shelves and shattered. Some power outages also were reported.
Social media revealed a photo of a home partially damaged.
There were no immediate reports of injuries.
Sunday’s quake occurred at a shallow depth estimated at 2.3 miles deep, according to the U.S. Geological Survey (which has been revising this number), amplifying the effects felt on the ground. Earthquake surface waves — the kind that produce the shaking we feel on the ground — travel farther on the East Coast than in the West. That’s because the crust east of the Rockies is less fragmented and more consolidated.
A 2.6-magnitude foreshock was registered at 1:57 a.m. near the epicenter of Sunday’s larger tremor.
Numerous aftershocks, many of which will be felt in the immediate vicinity of the 5.1-magnitude quake, are likely for upward of a week as the earth continues to settle, shift and release stress.
It is highly unlikely, but not impossible, that the 5.1 quake is itself a foreshock of a larger earthquake to come. That was the case in Ridgecrest, Calif., when a 6.4-magnitude quake on July 4, 2019, was followed by a 7.1-magnitude quake the next day.
At first glance, Sunday’s earthquake appears to have originated near the Eastern Tennessee seismic zone, a strip of seismic activity that stretches from the high terrain of eastern Tennessee northeastward up the Appalachians into the Carolinas. At least 5-magnitude or greater quakes have occurred in that pocket since the late 1600s, including near Sparta.
While rumors did briefly circulate on social media, Sunday’s quake did not appear to be associated with hydraulic fracturing, or “fracking.”
Initial data suggests the quake was from an oblique reverse-slip event.
Reverse faults are fractures in Earth’s crust that occur at an angle. Ordinarily, one block of crust is displaced vertically above the other. The higher fault, known as the “hanging wall,” is forced up the lower “foot wall.” Reverse faults feature the buildup of compressional stress. The Rocky Mountains and Himalayas were formed as a result of reverse fault processes.
Thrust faults are a type of reverse fault in which the interface between two blocks of crust is closer to horizontal than it is vertical. That, in essence, causes one plate to slip beneath another.
Sometimes, the blocks slip laterally alongside one another while one moves beneath the other. That appears to be the case with Sunday morning’s event, making it an “oblique reverse” slip.
Jason Samenow contributed to this article.