A 4.1-magnitude earthquake inTennesseewoke up families and rattled homes as far away as Atlanta as it spread tremors across portions of the southern US on Saturday morning. No injuries or major damage were immediately reported.
The website for the United States Geological Survey (USGS) said theearthquakeoriginated shortly after 9am EDT about 12 miles (20km) from Greenback, Tennessee, which is about 30 miles (48km) south of Knoxville.
More than 23,000 reports from the public were received by USGS in the first hour after the earthquake, USGS spokesperson Ayesha Davis told the Associated Press in an email. Meteorologists at television news stations serving Georgia and North Carolina reported feeling the tremors as well.
There is a 5% chance of a magnitude 4 or larger aftershock in the next week, according to USGS.
Gabriela Reilly was making waffles with her husband when they felt their entire home shake in Braselton, Georgia, which is north-east of Atlanta.
“Our ceiling fan started shaking for about 10 seconds,” she said. “I thought a giant aircraft had flown low right over the neighborhood, but my husband said: ‘No, that was definitely an earthquake.’”
Jason Pack was still in bed at his home outside Knoxville when he felt the walls shaking and heard a rumbling that was loud enough to wake up his family and for the dog to start barking.
“In eastTennessee, you’re used to tornadoes and floods, that kind of thing,” Pack said. “It’s unusual to have an earthquake.”
Pack has experienced tremors before, although this one is probably the strongest he’s felt in Tennessee.
“Even though this one was small, it’s a good reminder – if it had been a big quake, would you know what to do? Drop, cover and hold on if you’re inside,” said Pack, a retired FBI agent who now works in crisis communications. “Stay clear of buildings if you’re outside.”
Damage does not usually occur from earthquakes until they reach a magnitude of somewhere above 4 or 5, according to USGS, although it depends on variables such as building construction, soil and distance from the epicenter.
The south-eastern US carries a significant earthquake risk, particularly around the New Madrid seismic zone to the west and in the Eastern Tennessee seismic zone, which is where Saturday’s earthquake occurred, said Davis.
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Since 1950, 15 other earthquakes of magnitude 4 or larger have occurred within 155 miles (250km) of Saturday’s earthquake, Davis said. The largest of those was a magnitude 4.7 earthquake near Knoxville in November 1973.
More recently, two tremors struck the seismic zone in December 2018. One was a 4.4-magnitude earthquake centered in Decatur, Tennessee, which is south of Knoxville. It shook homes as far away as Atlanta.
Another earthquake struck a few days later with a magnitude of 3.0. Its epicenter was about 2 miles (4km) south-east of Mascot, near Knoxville. It was also felt in parts of Georgia, Kentucky and North Carolina.
Seismic waves from earthquakes spread more efficiently in the eastern US compared with the west because of the region’s geology, Davis said.
“Earthquakes in the east are felt over a much larger distance and by more people,” she said.