by Leah Justice

Many area residents may have been watching the Olympics, Friday, Feb. 14 at 10:23 p.m. and felt a strange shaking of their house.

According to the United States Geological Survey (USGS), a 4.1 magnitude earthquake struck approximately seven miles from Edgefield, S.C. in the midlands at 10:23 p.m. Friday. The quake was about 2.9 miles deep.

The earthquake was reported to be felt in South Carolina, North Carolina, Georgia and as far away as Tennessee and Virginia.

By 10:30 p.m., many foothills residents began posting on Facebook asking if anyone else felt the shake. Reports on
Facebook locally came from Landrum to Spartanburg and Inman, S.C. as well Polk townships and as far away as Charlotte and Georgia.

Comments flooded the Internet immediately, such as “my house just shook,” “was there just an earthquake,” and “I thought I was crazy” and “I thought I was loosing it.”

An aftershock also struck Edgefield, S.C. on Sunday, Feb. 17 at 3:23 p.m., according to the USGS, but no reports of Sunday’s quake were reported locally. Sunday’s aftershock was a 3.2 magnitude.

Polk County Emergency Management Director Bobby Arledge said Polk County Dispatch had several calls about the earthquake Friday night but there has been no damage reported locally.

South Carolina Emergency Management Division said South Carolina receives about 15-20 registered earthquakes per year and Friday night’s was the 13th and the largest in the past year. Friday night’s was the largest since a 4.4 earthquake struck Charleston in 2002.

The largest earthquake ever recorded in South Carolina and the east coast was a 7.6 magnitude in Summerville, S.C. that occurred on Aug. 31, 1886. Approximately 60 people died as a result of the 1886 earthquake and structures were damaged as far away as 200 miles from Charleston, S.C., according to reports.

The last earthquake felt in the Polk County/Landrum area occurred on Oct. 29, 2012 when a 2.9 magnitude earthquake struck eight miles south of Marion, N.C. Some residents reported feeling the earthquake while many did not.

On Aug. 23, 2011 a 5.9 magnitude earthquake struck central Virginia and was felt widespread by many in the Carolinas and as far north as Canada. The 2011 quake lasted approximately 10 seconds in Tryon.

Perhaps the largest earthquake felt in the Polk County/Landrum area in recent years occurred at 6:07 a.m. about six miles east of Columbus on Dec. 7, 2007. The USGS confirmed the earthquake between Lake Adger and Mill Spring was a 3.1 magnitude. The 2007 earthquake was reportedly by residents in Rutherfordton and Hendersonville to Landrum and Glassy Mountain, S.C.

According to the USGS, since 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. Earthquakes in 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 10 times larger than a similar magnitude earthquake on the west coast, according to the USGS.

A magnitude 4.0 eastern U.S. earthquake can typically be felt as far away as 100 km (60 miles) from where it occurred and infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake can be felt as far as 500 km (300 miles) from where it occurred and sometimes causes damage as far away as 25 miles from its source, according to the USGS.

Edgefield, S.C. is located approximately 120 miles from Landrum, north of Augusta, Ga. and southwest of Saluda, S.C.

Faults

Earthquakes occur on faults within bedrock, usually miles deep. Most bedrock beneath the inland Carolinas was assembled as continents collided to form a supercontinent approximately 300-500 million years ago, raising the Appalachian Mountains, states earthquake.usgs.gov. Most of the rest of the bedrock formed when the supercontinent rifted apart about 200 million years ago to form what are now the northeastern U.S., the Atlantic Ocean and Europe.

At well-studied plate boundaries like the San Andreas fault system in California, scientists can determine the name of the specific fault that is responsible for an earthquake but east of the Rocky Mountains this is rare. The inland Carolinas, according to the USGS, is far from the nearest plate boundaries, which are in the center of the Atlantic Ocean and in the Caribbean Sea.

“It is difficult to determine if a known fault is still active and could slip and cause an earthquake,” states the USGS website. As in most other areas east of the Rockies, the best guide to earthquake hazards in the seismic zone are the earthquakes themselves.”

The highest risk of fault line near Polk County is the South Carolina coast and a section where western Tennessee meets Arkansas, Missouri, Mississippi and Kentucky, according to fault line maps.