The August 9th, 2020 M 5.1 earthquake near Sparta, North Carolina, occurred as a result of oblique-reverse faulting in the upper crust of the North American plate. Focal mechanism solutions for the event indicate rupture occurred on a moderately dipping fault either striking to the northwest or south. 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. This earthquake was preceded by at least four small foreshocks ranging from M 2.1-2.6, beginning about 25 hours prior to the mainshock.
Large earthquakes are relatively uncommon in the region directly surrounding the August 9th M5.1 earthquake. Moderately damaging earthquakes strike the inland Carolinas every few decades, and smaller earthquakes are felt about once each year or two. In the 20th century, one earthquake M5 and larger occurred within 100 km to this August 9th events, a M5.2 in the Great Smoky Mountains in 1916. The largest recent earthquake to impact the east coast was the M5.8 Mineral Virginia earthquake on August 23rd, 2011, roughly 300 km to the northeast of this August 9th earthquake. The Mineral Virginia earthquake was felt widely across the east coast and caused slight damage.
