The Friday night earthquake near Edgefield shook the ground more in Hollywood than at a monitoring station in the Upstate, experts said Saturday.
South Carolina quakes
Significant earthquakes experienced in South Carolina, according to the U.S. Geological Service.
1886: Centered in Charleston. Magnitude 7.3 - the biggest in state history. Quake followed by seven aftershocks. About 60 people killed. Few buildings in the city escaped damage. Damage in Columbia, Augusta and Savannah, Ga. All or parts of 30 states, Ontario, Canada, and Havana, Cuba, felt the earthquake.
1903: Centered on the South Carolina-Georgia border near Savannah with tremors reaching Charleston, Columbia and Augusta, Ga.
1907: Moderate shock felt in Charleston, Augusta and Savannah
1912: Centered in Summerville and felt in Charleston, Greenville and Brunswick and Macon, Ga., and Wilmington, N.C.
1913: Centered in Union County
1914: Centered in Summerville and felt in Charleston and Augusta, Macon and Savannah, Ga.
1924: Centered in Pickens County and felt in most of South Carolina and western North Carolina, northeastern Georgia, and eastern Tennessee.
1945: Centered in Lake Murray and felt in parts of Georgia, North Carolina and Tennessee.
1959: Shock felt in Charleston, Summerville and Wadmalaw Island.
1960: Centered off the coast of South Carolina and felt in Augusta and Greensboro, N.C..
1958: Centered in Anderson
1959: Centered in Chesterfield
1964: Centered in Gaston and felt in Fairfield, Florence, Lexington and Richland Counties.
1971: Centered in Bowman and Orangeburg, Magnitude 3.4.
2002: Centered in Seabrook Island. Magnitude 4.4. Felt along the coast from Myrtle Beach to Beaufort
The reason is deep, sandy Lowcountry soils amplify earthquake seismic waves, said Steve Jaume, an associate professor and quake expert at the College of Charleston.
"We have thousands of feet of this weak, wiggly stuff. Think bowl of Jell-O," he said.
The 4.1 magnitude quake in Edgefield County would likely have more impact if it happened here, he said.
"The ground shakes harder so you expect greater damage," Jaume said.
The temblor occurred at 10:23 p.m. and was centered seven miles west-northwest of Edgefield.
No damage or injuries occurred, officials said. Some residents reported shaking strong enough to rattle glasses off of a cooler and onto the floor, according to news reports.
The quake was noticed in the Carolinas, Tennessee, Georgia and Alabama, the U.S. Geological Survey reported.
"I had e-mails from students who felt it," said Erin Beutel, an associate professor at the college who is also an earthquake expert.
A seismometer here recorded significantly more horizontal ground motion than one located closer to the epicenter in the hard-rock soil of the Upstate at Campobello, the college said.
"It's the dirt under the feet that literally makes the difference," Jaume said.
The ground here is more likely to become unstable during an earthquake, the experts said.
In response to Friday's quake, the South Carolina Department of Transportation on Saturday conducted inspections of bridges in an area from Anderson and Greenville to Aiken, Edgefield and Orangeburg. No damage or safety concerns were reported. Quake-related bridge inspections were not necessary here, the DOT said.
Quake prediction is not yet possible. The chances of a minor to moderate earthquake here over a lifetime are pretty good, Beutel said.
"We really don't understand earthquakes," she said.
But it's known that the Lowcountry is more at risk for damage if an earthquake occurs, she said.
The South Carolina Emergency Management Division and seismic experts have joined together to create a response plan in the event of a major earthquake, she said.
"On a state level, we seem to be fairly prepared," she said.
Residents should have an earthquake kit with enough water, food, clothing and other items to last at least 72 hours, she said.
The best immediate response to a quake is to seek shelter under a table or desk. Running outside or standing in a doorway increases the likelihood of being injured by a falling object, she said.
"Statistically, you are much more likely to be injured or killed if you move more than 10 feet. It's a hard instinct to fight," she said.
Earthquakes in the central and eastern United States, although less frequent than in the western U.S., are typically felt over a much broader region. East of the Rockies, an earthquake can be felt over an area as much as ten times larger than a similar magnitude quake on the west coast, experts say.
Charleston and its surroundings were devastated by a 7.3 magnitude earthquake in 1886. Aftershocks, some of them damaging, continued for years. If that sort of quake were to happen again, the damage would be like that in Christchurch, New Zealand in 2011, Jaume said.
In response to the quake threat, communities such as Charleston have adopted building codes that increase the likelihood of a structure remaining intact during a temblor. And historic buildings have been retrofitted to make them more likely to stay standing during the energy released by an earthquake.