Mild earthquake shakes Barnwell County, but leaves it unharmed

Barnwell County experienced a mild earthquake last week, but the event caused no reported damage or injuries.

According to data from the U.S. Geological Survey, at 12:06 p.m., March 27, the area experienced a 2.6 magnitude earthquake on the Richter scale.
Roger Riley, the emergency management director for the county said he got verification on the earthquake a few hours after it occurred.

"I've had about six to eight calls; people calling 911. People said mostly they heard a loud boom and reported shaking. The first call I had was at 12:12 p.m.," he said.

"I called the Emergency Management Division in Columbia about it. They in turn contacted the National Weather Service, who confirmed it," he said.

Seismometers in Jenkinsville in Fairfield County in the northern central portion of the state were tripped, according to data from the S.C. Earthquake Education and Preparedness Program (SCEEP).

Further data from the U.S. Geological Survey estimates the seismic activity occurred within a region about one mile northwest of Elko; two miles east-southeast of Williston; seven miles west-northwest of Blackville and about 22 miles east-southeast from Aiken.

The earthquake occurred about 1.1 miles below the earth's surface, according to USGS data.

Riley estimates the most activity the earthquake generated in Barnwell County centered on the Snelling township area toward S.C. 39 and the Fellowship Road area, he said.

"The biggest concentration of (telephone) calls came from the Williston barricade to Snelling," Riley said.

The barricade Riley refers to is the boundary of the Savannah River Site.

"We didn't get any further calls about it over the weekend about any damage," Riley said.

Richard Côté, the director of the S.C. Earthquake Awareness Project, estimates that the Barnwell County earthquake was an "intra-plate" earthquake due to "weaknesses in the earth's structure," he said.

Slow shifts in one plate can release energy, which is felt on the surface as an earthquake, Côté said.

South Carolina sits on top of a tectonic plate and not at the edge of two continental plates. California, known for its earthquake activity, is located where two tectonic plates come together. When these plates shift or rub together, earthquakes happen, he said.

However, within individual tectonic plates, some movement can occur that can create earthquakes, Côté said.

Côté is the author of "City of Heroes: The Great Charleston Earthquake of 1886." He is also an advocate for better earthquake preparedness in the state.

Côté said there is no way to know whether Barnwell County's earthquake is a precursor to another - larger - one in the near future.

"There's no scientist on earth that can tell you when the next one will occur," he said. "We may not get another one for 1,000 years. There's no predicting them, there's no sequencing them. They are highly unpredictable. You have to be generically prepared. There's no known pattern."

Côté uses his research into the Charleston 1886 earthquake as evidence of this natural phenomenon's unpredictability.

"There were some smaller earthquakes before 1886 but there had been a number of small earthquakes 125 years before 1886," he said.

The Richter scale measures the intensity of the seismic activity below the surface at the point of the geological shifting, which is known as the epicenter of an earthquake. The area on the surface above the epicenter is the hypocenter. The deeper underground the epicenter is, the wider an area the earthquake is felt.

Alaska, California, Missouri and South Carolina are the four most earthquake active states in the nation.

The region around Charleston and Summerville is one of the most seismically active areas in the United States east of the Mississippi River, according to the S.C. Earthquake Education and Preparedness Program at the College of Charleston.

According to the SCEEP, the region has the following earthquakes in recent years:

• On May 24, 2008, a 2.4 magnitude earthquake shook Columbia.

• On Dec. 16, 2008, a 3.6 magnitude earthquake occurred south-southwest of Summerville.

• On Jan. 29, 2009, a 2.5 magnitude quake was recorded in the Charleston-Summerville area.

For more data on earthquakes, check online at: www.scearthquakes.cofc.edu or www.scearthquakes.com.