The U.S. Geological Survey said five small earthquakes struck near the Tennessee-North Carolina border in about as many hours.
The first quake registered at 2:48 a.m. and the fifth was reported just before 7 a.m. on Tuesday, according to the agency. The quakes were between magnitudes 1.3 and 1.7 on the Richter scale.
The swarm hit around 25 miles southwest of Knoxville, Tennessee. The agency said they are likely too small to be felt by locals.
“Earthquakes too small to cause damage are felt about once a year. Earthquakes too small to be felt are abundant in the seismic zone, and seismographs have recorded hundreds of them in recent decades,“ the USGS said.
The USGS noted that the area where the quakes hit is one of the most seismically active regions in the southeastern United States. The largest quake in recent memory was a 4.6 that struck in Fort Payne, Alabama in April 2003.
“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,” the seismic agency wrote.
A 4.0 magnitude quake on the U.S. East Coast can be felt as far as 60 miles away, it noted. A 5.5 magnitude tremor can be felt for 300 miles and can cause damage 25 miles away.
And some people might hear sounds associated with these small earthquakes.
“No one knows for sure, but scientists speculate that these ‘booms’ are probably small shallow earthquakes that are too small to be recorded, but large enough to be felt by people nearby,” the USGS said, according to local station WVLT.
