North Carolina experiences earthquakes, although they are generally infrequent and mild compared to those along tectonic plate boundaries. The state is located within a Stable Continental Region (SCR), meaning its seismic activity is not directly caused by the friction between major plates. Recorded tremors confirm that seismic forces are active beneath the state’s surface. This activity typically registers at a low magnitude. While the risk of a major earthquake is low, the potential for moderate seismic events remains a factor in the state’s natural hazard profile.
Historical Seismic Activity in North Carolina
Earthquakes in North Carolina are typically scattered and relatively small events, with the majority of activity concentrated in the western part of the state, particularly the Blue Ridge region. Since 1776, the state has recorded over 80 events strong enough to be felt. Moderately damaging earthquakes strike the inland Carolinas every few decades, with smaller events felt about once every year or two.
The most significant recent event was the magnitude 5.1 Sparta earthquake that struck Alleghany County on August 9, 2020. This shallow quake was the strongest in North Carolina in over a century and caused damage to homes and businesses in Sparta. Before Sparta, the largest recorded quake with an epicenter in the state was a magnitude 5.2 event near Skyland in 1916, which caused chimneys to fall and windows to crack in the mountain region.
North Carolina has also been strongly affected by major regional earthquakes originating outside its borders, most notably the 1886 Charleston, South Carolina, earthquake. That event, estimated to be between magnitude 6.6 and 7.3, was felt across the entire state, cracking chimneys and plaster walls as far as Asheville and Raleigh.
The Geology Behind NC Earthquakes
North Carolina sits firmly on the North American tectonic plate, thousands of miles from the nearest plate boundary, placing it in a Stable Continental Region. Earthquakes occurring here are known as intraplate earthquakes. The mechanism for these tremors involves the reactivation of ancient, deep-seated fault lines that formed hundreds of millions of years ago.
These faults were created during massive tectonic events, such as the formation of the Appalachian Mountains and the subsequent opening of the Atlantic Ocean. Although they are geologically old, these zones of weakness remain in the crust. Regional stress is constantly transmitted through the North American plate, a pressure thought to be driven by slow-moving forces like the push from the Mid-Atlantic Ridge.
When this immense, stored stress reaches a breaking point, it overcomes the friction along one of these pre-existing faults, causing it to slip and release energy as an earthquake. Because the crust in the Eastern US is older, colder, and harder than in the West, seismic waves travel more efficiently, causing the shaking from an intraplate quake to be felt over a much larger area.
Earthquake Safety and Preparedness
Although the risk is low, residents should still prepare for the possibility of a sudden earthquake, as they strike without warning. The most important safety procedure during shaking is to “Drop, Cover, and Hold On.” This means dropping to the floor immediately, taking cover under a sturdy table or desk, and holding onto it until the shaking stops.
Preparation at home involves mitigating non-structural hazards, which cause most earthquake-related injuries. Securing heavy furniture, such as bookcases and water heaters, to wall studs prevents them from toppling over. Heavy or breakable objects should be placed on lower shelves, and any deep cracks in foundations or ceilings should be repaired. Additionally, maintaining a basic emergency kit with water, food, and first-aid supplies ensures readiness for a short period following any unexpected event.