Imagine being jolted away by a thundering boom from underground.
Sullivan County resident Jean Robinson tells News 5 it happened to her Saturday night.
"Oh yes, very strange,” said Jean Robinson.
Robinson tells us this winter has been one of the coldest and most unpredictable she's ever experienced.
But the wacky weather doesn't compare to what she heard around 8:30 p.m. Saturday.
"I was sitting in my chair and I heard what sounded like a sonic boom go off and I bolted out of my chair,” said Robinson.
Robinson tells us she's lived in her Piney Flats home near Tri-Cities Regional Airport for more than 30 years.
"It was very loud and it shook my house,” said Robinson.
And we she heard the boom she feared the worst.
"I ran to my kitchen window to look out, because the airport is nearby. And my first thought was something had happened at the airport,” said Robinson.
But that wasn't the case, and Robinson wasn't the only one who heard the strange noise.
More than 50 people wrote on our WCYB Facebook wall saying they heard the blast and many 911 centers got calls about the noise.
We reached out to ETSU geology professor Steven Wallace who says it was likely a phenomenon called a cryoseism.
Wallace told us a cryoseism is a natural event in which ice breaks underground.
In this case the phenomenon likely happened after we experienced several of days of single digit temperatures followed by Saturday’s quick warm up into the 60s and the release of the heat can cause an exploding sound.
Wallace told us the event typically occurs in the Great Lakes region, but after our abnormal winter this natural occurrence comes as no surprise.
But Robinson is still shocked and surprised by the cryoseism.
“I heard dynamite go off and I’ve heard different explosions. But it was louder than anything I’ve ever heard, said Robinson.
We're told it's highly unlikely that damage or injuries will occur from cryoseisms.