NORTH CAROLINA (WCMH) – A 5.1-magnitude earthquake occurred Sunday morning near Sparta, N.C., according to USGS. in the northwestern part of the state near the North Carolina-Virginia border.
The earthquake shook much the mostly rural region early Sunday, rattling homes, businesses and residents. The National Weather Service in Greenville-Spartanburg, S.C., said the 5.1-magnitude temblor struck at 8:07 a.m., following a much smaller quake several hours earlier.
Minor structural damage was seen around Sparta, including cracked roadways and fallen items from shelves, but no injuries were reported. One home had a substantial foundation crack nearly up to the roof.
Sunday morning’s quake was the largest to hit the state since July 1926, when a magnitude-5.2 quake occurred about 50 miles northeast of Asheville, N.C., according the state’s Department of Environmental Quality (DEQ). Ten years earlier, a 5.5 magnitude earthquake was centered around Skyland, south of Asheville.
Sunday’s earthquake occurred in the East Tennessee Seismic Zone, far away from a seismically active plate boundary. In the interior U.S., compressional stress builds up over time in the North American Plate as it drifts along on the semi-molten, soft mantle. Pent-up energy is released along ancient faults or fractures that date back to the formation of the Appalachian Mountains hundreds of millions of years ago, triggering an earthquake.
The depth of the earthquake Sunday in northwestern North Carolina was 3.1 miles below the surface. Earthquakes in the eastern U.S. tend to be relatively shallow and travel farther because the sediment is more consolidated and brittle.
The earthquake occurred on a thrust fault, a type of reverse fault in which one block above the fault rises up and over another block of earth at an angle of less than 45 degrees.
Earthquakes near the Pacific Coast, such as along the notorious San Andreas Fault in southern California, occur along a transform fault, where two tectonic plates are moving past each other. This is a complex type of strike-slip fault associated with two blocks sliding laterally.
There were a minimum of four foreshocks (2.1 to 2.6 ) a little more than 24 hours before Sunday morning’s earthquake in the foothills of the Great Smoky Mountains, according to the U.S. Geological Service. The epicenter was placed at about 2.5 miles southeast of Sparta, North Carolina. The moderate quake was felt in Virginia, South Carolina, and Tennessee.