A minor quake late Sunday shook people awake in the Summerville area.
More than 400 residents in the town, Ladson and Goose Creek notified the U.S. Geological Survey they had felt the 2.3 magnitude temblor just before 11 p.m.
It was slightly below the magnitude 2.5 where some damage might occur. USGS characterizes strengths below 2.5 as akin to the shake of a big truck going past.
The rumble appeared to be centered near Orangeburg Road, just southwest of downtown Summerville.
A resident commenting on the Twitter account for National Weather Service in Charleston described it as a small thud.
Small temblors rattle the Charleston area, as well as the region, all the time. But the nighttime disruption wasn't good for nerves already rattled by coronavirus concerns. Another resident commenting on the Twitter account described it as feeling like an explosion shook the house for a second.
The quake came about two months after a series of quakes in Columbia followed devastatingly strong quakes in the Caribbean Sea.
The main thing I have to say is "Finally!". The Summerville area has been quiet since November 2018 (more than a year), which is a little uncommon.
The coastal area around Charleston is particularly vulnerable to quakes. Three faults underground converge on each other somewhere below the Ashley River near Middleton Place. The edges of tectonic plates pressing against each other launch the temblors.
The faults were ground zero for the 1886 quake, a 7.3 magnitude temblor considered the worst recorded in the eastern United States. The cluster of quake and aftershocks killed 100 people, leveled nine of every 10 brick buildings in Charleston and damaged nine of every 10 in Summerville.
A quake usually must reach around magnitude 5 before any serious damage would be expected.
The Sunday quake was the third modest rattle in the state in March. But it was the first shake-prone fault convergence since November 2018, said Steve Jaumé, a College of Charleston geology professor who tracks temblors as part of the South Carolina Earthquake Education and Preparedness program.
"We usually have two or three felt events per year. But this is also how 'random' natural processes actually work. There will be periods of less than normal activity balanced by periods of more than normal activity. It is difficult to impossible to see any real patterns in earthquake activity," Jaumé said.
Some 900,000 quakes less powerful than 2.5 magnitude occur around the world each year.