An earthquake rattled South Carolina late last night; it’s epicenter was away from the previous Elgin-centered swarm area in the state. According to USGS, the relatively weak 1.9 magnitude event struck at 11:03 pm last night. Despite the intensity and the time it struck, ten people used the USGS “Did you feel it?” tool on their Earthquakes website to report feeling shaking. The epicenter was located just outside of Hopkins, South Carolina; it struck at a depth of only 6 km.
According to the South Carolina Emergency Management Division (SCEMD), there are approximately 10-15 earthquakes every year in South Carolina, with most not felt by residents; on average, only 3-5 are felt each year. Most of South Carolina’s earthquakes are located in the Middleton Place-Summerville Seismic Zone. The two most significant historical earthquakes to occur in South Carolina were the 1886 Charleston-Summerville earthquake and the 1913 Union County earthquake. The 1886 earthquake in Charleston was the most damaging earthquake to ever occur in the eastern United States; it was also the most destructive earthquake in the U.S. during the 19th century.
Experts are concerned that a large scale earthquake will strike at some point of the future and bring about significant damage and loss of life. While more than 100 years have passed since the last large earthquake, a 2001 study titled “Comprehensive Seismic Risk and Vulnerability Study for the State of South Carolina” confirmed the state is extremely vulnerable to earthquake activity. The study, based on scientific research, provided information about the likely effects of earthquakes on the current population and on modern-day structures and systems, including roadways, bridges, homes, commercial and government buildings, schools, hospitals and water and sewer facilities.
Since December 2021, South Carolina has been dealing with a mysterious swarm of earthquakes near Elgin. However, today’s earthquake struck roughly 10 miles south from where most Elgin-swarm quakes have hit.
The mysterious swarm began on Monday, December 27, at 2:18 pm in the afternoon. That first 3.3 magnitude earthquake hit 30 miles north of Columbia, South Carolina at a depth of only 3.1 km. More than 3,100 residents reported to USGS they felt it at the time, with one report of shaking coming from as far away as Rock Hill, which is at the North/South Carolina state border. While many felt the earthquake, there was no reported damage in the Palmetto State. That earthquake was followed by 10 more ranging in intensity between a magnitude 1.5 to a magnitude 2.6 event. The second earthquake struck three hours twenty minutes after the first one. More than 80 other earthquakes struck there throughout 2022 as the unusual swarm continued.
According to USGS, a swarm is a sequence of mostly small earthquakes with no identifiable mainshock. “Swarms are usually short-lived, but they can continue for days, weeks, or sometimes even months,” USGS adds. However, the South Carolina event in Elgin doesn’t fit the typical definition of a swarm since the first event was substantially larger than the rest.
It is not yet known whether this earthquake has any relationship to the Elgin swarm. Elgin hasn’t had a quake in the last 30 days and it’s too soon to know if more earthquakes will happen in either of these places in the coming days and weeks.