The U.S. Geological Survey reported a 4.1 magnitude earthquake Friday night centered seven miles west-northwest of Edgefield.
The quake could be felt throughout South Carolina and Georgia, based on social media reports.
There were no reports of damage or injuries, even in the epicenter of Edgefield County, S.C. Emergency Management Division spokesman Derrec Becker said.
Travis Seigler, manager of Michelle’s Pizza and Grill in McCormick, said the tremor was strong enough to knock several glasses off a cooler and onto the floor, where they broke. Otherwise, it wasn’t a big deal.
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“We’re right beside a railroad track, so we’re used to that sort of thing,” Seigler said. “It felt a little stronger, so we looked outside the door and there was no train.”
Cameras mounted on the nearby Thurmond Lake dam did not show any damage from the quake, said Billy Birdwell, a spokesman for the U.S. Army Corps of Engineers, which manages the lake.
Saturday evening, the state Department of Transportation said bridges near the epicenter and several surrounding counties were safe.
DOT specialists began bridge inspections at daybreak Saturday near Edgefield and on U.S. 378 at the Savannah River, on U.S. 29 below Lake Hartwell and on S.C. 34 at the Saluda River below Lake Greenwood. Inspectors also checked around the Oconee Nuclear/Keowee hydroelectric area.
The I-20 Savannah River bridges are owned and maintained by Georgia's DOT. South Carolina and Georgia officials were coordinating their responses, S.C. authorities said.
Doug Busbee, a resident of nearby Wagener, felt the quake rock his house as he lay in bed Friday night.
“It sounded kind of like a train coming,” he said. “The whole ground shook. It kind of felt like the whole house was swaying.”
Edgefield resident Alva Lewis, 68, said she was “very, very scared’’ as her house shook for 10 to 15 seconds during Friday night’s earthquake. She said she didn’t realize what was happening at first.
“It sounded almost like an explosion,” Lewis said. “I thought it was a truck collision. I said nobody could have survived that. It lasted about 10 to 15 seconds. I never felt anything like that before.”
Earthquakes are common in South Carolina, with 12 in the past 13 months.
But none of the previous 11 were of a magnitude of more than 2.5, according to the S.C. Department of Natural Resources’ earthquake webpage. This one also gave a bigger rumble than most.
Emergency Management’s Becker said it was the biggest earthquake to hit the state since 2002.
The last earthquake of similar magnitude to hit the state – or nearby – was a 4.4 quake, just offshore of Seabrook Island on Nov. 11, 2002.
“This was a big one, relatively speaking,” said Dale Grant, a geophysicist with the US Geological Survey. “Very rare.” Grant said this earthquake was shallow so the effects were felt over a larger area.
Lowcountry residents felt the quake more acutely than did people who live near a monitoring station in Campobello, near Spartanburg, according to scientists in the South Carolina Earthquake Education and Preparedness program at the College of Charleston’s Department of Geology and Environmental Geosciences.
The hard-rock soil of the Upstate rumbles less than the sandy areas along the coast. That's also why earthquakes, even of a low magnitude, do more damage along the coast, the scientists said Saturday morning.
Geologists said the quake happened three miles underneath the earth's surface.
Eric Strom, director of the U.S. Geological Survey's water science office in Columbia, said the quake "was pretty good sized'' one for this part of the country.
"You can typically feel a 4.0 as far as 60 miles away,'' he said.
Because faults are not mapped as well in South Carolina as in California, Strom said it was difficult to tell initially which fault was connected to the Valentine's Day quake.
He said damage to buildings can depend on "the site-specific conditions of your home and the foundation."
Jim Landmeyer was tucking his eight-year-old daughter into bed when both noticed their two-story home in Blythewood, north of Columbia, shaking.
"It felt like military helicopters were perched on top of my house, the downdraft was shaking the house,'' he said . "There was a rumble. The house shook a little bit and my daughter asked me 'Dad, what's going on?'"
Landmeyer, an official with the U.S. Geological Survey, soon realized that an earthquake was occurring. He ran into his second daughter's room and "her bed was just shaking back and forth. A couple of books had fallen off her shelf.''
The shaking lasted about 5 to 6 seconds, he said.
In a 10-minute period, a geological survey website registered about 2,000 comments in which people said they had felt the shaking, said Landmeyer, who confirmed for his neighbors that a quake had occurred.
Unlike California earthquakes, tremors in South Carolina are not the result of "plate to plate contact,'' he said. Instead, plates are being stretched, like a rubberband being pulled, Landmeyer said.
Gov. Nikki Haley, who felt the earthquake at the Governor’s Mansion, checked in with state officials already assembled at an emergency center in West Columbia, activated for this week’s winter storm, her office said.
The quake at 10:23 p.m. was centered along the edge of Thurmond Lake, just north of the area hardest hit by this week’s ice storm.
Reports surfaced on Twitter of a leaking water tower in Augusta following the quake. The tower was damaged by ice from a winter storm earlier this week, not the quake, said Richmond County Sheriff’s Lt. Tangela McCorkle.
From U.S. Geological Survey:
Since at least 1776, people living inland in North and South Carolina, and in adjacent parts of Georgia and Tennessee, have felt small earthquakes and suffered damage from infrequent larger ones. The largest earthquake in the area (magnitude 5.1) occurred in 1916. Moderately damaging earthquakes strike the inland Carolinas every few decades, and smaller earthquakes are felt about once each year or two.
Earthquakes in the central and eastern U.S., 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 earthquake on the west coast. A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source.