February 18, 2014
The U.S. Geological Survey has confirmed that a 4.1 magnitude earthquake centered near Edgefield struck around 10:22 p.m. Friday, sending tremors throughout the Carolinas and Georgia.
The USGS indicated that the quake was about three miles deep and was centered seven miles west northwest of Edgefield.
Dale Grant with the USGS said shallow quakes like this one generate most of their energy near the surface. He confirmed to a local news channel that it was felt throughout South Carolina, into Georgia and into North Carolina.
Derrec Becker, public information coordinator for the S.C. Emergency Division, said Friday night that earthquakes in South Carolina are not that uncommon.
“South Carolina normally experiences 15 to 20 earthquakes a year,” said Becker. “Those are very, very low magnitude quakes. A 4.0 is very visible.”
Becker said the effects of a 4.0 magnitude earthquake would be visible, such as books falling off shelves or dishes falling, and would feel like a large truck just drove by.
“At first we thought it was a National Guard helicopter that flew over the building because that’s happened all day,” he said. “We are going through our plans and procedures to make sure that everything is OK in the state because of everything we have already gone through this week.”
According to the U.S. Geological Survey, residents of the Carolinas, Georgia and Tennessee have been experienced small earthquakes and suffered damage from larger ones since 1776.
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, according to USGS.
A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 60 miles from where it occurred, and it infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 300 miles from where it occurred, and sometimes causes damage as far away as 25 miles, according to the USGS.
According to the U.S. Geological Survey Website:
Earthquakes occur on faults within bedrock, usually miles deep. Most bedrock beneath the inland Carolinas was assembled as continents collided to form a supercontinent about 500-300 million years ago, raising the Appalachian Mountains. 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.
The inland Carolinas region is laced with known faults but numerous smaller or deeply buried faults remain undetected. Even the known faults are poorly located at earthquake depths. Accordingly, few, if any, earthquakes in the inland Carolinas can be linked to named faults.
Fairfield County residents’ reaction
Tremors from Friday night’s earthquake were even felt by some folks in Fairfield County including Patricia Weldon, who wrote, “Wow that was a lot of shaking,” on The Herald Independent’s Facebook page.
There were also an earthquake of 3.2 magnitude reported by the U.S. Geological Survey seven miles west of Edgefield at 3:23 p.m. Sunday.
Not nearly as strong as its predecessor, Sunday’s earthquake was only felt about 35 miles from its center, while Friday’s quake was reported more than 150 miles away.
Nancy Glenn (Irmo) and Dennis Brannon (Winnsboro) stated they did not feel the aftershock on The Herald Independent’s Facebook page.