A boom and a long rumble shook coastal residents Tuesday morning, less than two days after a small earthquake shook Summerville.
But this time something blew up, most likely.
An Air Force explosive ordnance disposal crew set off four controlled detonations on Joint Base Charleston, said base spokesman Sgt. Jonathan Lovelady. The crew wouldn’t provide details for security concerns. The command includes the Air Force Base in North Charleston and the Naval Weapons Station in Goose Creek.
The minute-long reverberation at 10 a.m. was felt at least the coastal length of Charleston County and as far inland as Moncks Corner.
“It felt like I was sitting on a Harley-Davidson (motorcycle) in idle,” said Russell Mitchum, who felt it in Awendaw. “It was enough to shake the house pretty good.”
Isle of Palms resident Garrett Krause said the shake felt like a quake, which the former Los Angeles resident said he’s experienced.
In a tweet, a James Island resident described it as feeling like somebody running across the roof.
The rumble wasn’t an earthquake. Seismometers didn’t report any temblors, said Steve Jaumé, a College of Charleston geology professor who tracks quakes as part of the South Carolina Earthquake Education and Preparedness program.
The U.S. Geological Survey didn’t report any temblors.
If it wasn’t the detonation, it could have been a sonic boom or the mysterious Seneca Guns. Jet aircraft in training occasionally set off the booms.
Reverberations from the “guns” rattle the Charleston area, as well as the region, all the time. The phenomena are periodic, so-far-unexplained reverberations felt along coasts around the world.
Some experts speculate the booms are caused by gases released from the sea floor, or undersea landslides along the Continental Shelf.
Among other guesses are the echoed sound of distant thunder, or lightning-like electrical discharges, even meteors crashing into the atmosphere at angles.