2020 Sparta earthquake

The 2020 Sparta earthquake was a relatively uncommon intraplate earthquake that occurred near the small town of Sparta, North Carolina, on August 9 at 08:07 ET. The thrust-faulting earthquake had a moment magnitude of 5.1, and a shallow depth of 7.6 km. Rupture occurred on the previously unmapped Little River Fault. Shaking was reported in parts of the Midwestern, and Southeastern United States. It was the strongest earthquake recorded in North Carolina in 104 years, the second-strongest in the state's history, and the largest to strike the East Coast since the 2011 Virginia earthquake. A surface rupture was documented following the earthquake; the first of its kind in the Eastern United States.

Earthquake
Measuring 5.1, it was the state's largest earthquake since a magnitude 5.2 earthquake struck Skyland in 1916. Over 80,000 people reported shaking from the earthquake.

Tectonic setting
The earthquake occurred near the Piedmont region and Blue Ridge Mountains, part of the eastern Appalachian Mountains which formed due to an ancient continental collision with the African Plate, during the Ordovician period, roughly 480 million years ago. This led to the formation of a supercontinent known as Pangaea. During the orogeny, many thrust faults were formed. Continental collision extended for the next 250 million years, forming the Caledonian, Acadian, Ouachita, Hercynian, and Allegheny orogenies. When Pangaea broke up beginning in the Early Mesozoic, uplifting of the Appalachians ceased, leading to increased erosion rates due to the steep terrain. Another period of uplifting the eroded topography occurred during the Cenozoic Era which led to aggressive erosion by rivers and streams.

The mainshock source area was in the Blue Ridge Mountains of the Alleghanian orogeny. Faults in this part of the range typically trend northeast. The earthquake ruptured along a fault trend that is consistent with west–northwest to east–west striking structures that crosses major northeast-trending geological structures of the mountain range. However, the geology of these faults are poorly understood. The earthquake occurred in a region that progresses between thrust and strike-slip tectonics; the dominant crustal strain is configured in a northeast–southwest to east-northeast–west-southwest direction.

Geology
According to the United States Geological Survey, the mainshock was the result of oblique-reverse faulting within the shallow crust of the North American Plate. The focal mechanism solutions for the earthquake indicate rupture occurred on a moderately dipping fault either striking to the northwest or south. This earthquake occurred in the interior of the plate, known as an intraplate earthquake. Four aftershocks of magnitudes between 2.1 and 2.6 were recorded beginning about 25 hours prior to the earthquake. The strongest of the sequence was a aftershock that struck two days after the mainshock. There were 20 recorded aftershocks by August 28. In Sparta, it had an estimated maximum Modified Mercalli intensity of VI–VII and the peak ground acceleration exceeded 0.2 g.

A 1.5 mi surface rupture associated with the earthquake was discovered southeast of Sparta. The fracture exposed a previously unmapped fault, dubbed the Little River Fault. Trenching of the Little River Fault indicate it is a thrust fault with at least 10 cm of displacement. This west-northwest–east-southeast striking fault slices through the local Paleozoic rocks. It featured a vertical scarp, or drop-off, of 9 in at its highest point. It was the first ever documented surface rupture from an earthquake in the Eastern United States, and the second observation made in Eastern North America. The rupture buckled a local road, damaged water lines, and several properties.

Damage
Widespread damage occurred in Sparta, which had already been debilitated by the COVID-19 pandemic in North Carolina. The town's manager, Ryan Wilmoth, said there were "very minor injuries" but did not specify the number of people injured. Within a week of the earthquake, there were 60 cases of serious damage and 465 minor damage reports. Nineteen people lost their homes and 25 were declared uninhabitable. Damage include collapsed ceilings, chimneys, and masonry; damaged water mains; cracked and deformed roads; uprooted headstones; and displaced appliances and items. The earthquake was felt in Washington D.C., Atlanta, and parts of Tennessee and Ohio.

Aftermath
Wes Brinegar, the town's mayor, issued a state of emergency to apply for FEMA and state financial aid. At least $112 thousand in state assistance grants were handed out to the affected. The Small Business Administration issued $1.17 million in loans. As the earthquake and its aftermath did not meet FEMA's disaster assistance criteria, the legislature of North Carolina allocated $24 million for relief. The project and its funding established a three-year project, Earthquake Recovery Program, operated by the Office of State Budget and Management and North Carolina Emergency Management. By 2021, there were over 230 requests for home repair assistance, averaging $44 thousand per home.

Brinegar also cautioned residents of scams on GoFundMe as officials did not raise any request on the site. Scammers took advantage of the damage, charging people up to $500 for repairs and failing to show up. Governor of North Carolina, Roy Cooper, toured the damage in Sparta, releasing a statement later, stating "We’ve dealt with a hurricane, a violent tornado, and now an earthquake all in the middle of a pandemic: North Carolinians are resilient."