A relatively small earthquake early Monday morning shook parts of Bath County, the Kentucky Geological Survey said.
The quake, estimated at magnitude 2.7, occurred just before 6 a.m., roughly centered between Owingsville and Sharpsburg, said Seth Carpenter, a seismologist with the geological survey in Lexington.
Stephanie Stewart, the Bath County emergency management director, said no damage was reported to her office. Most residents heard a rumble and simply thought it was thunder, she said.
"Everybody I've talked to said it sounded just like thunder and they thought it was thunder," Stewart said. "I live on the other side of the county and I didn't feel it at all."
Earthquakes are relatively rare in Kentucky, but they are not unexpected in the Bath County area, according to Carpenter, the seismologist.
About 17 quakes have been identified in the area over the years, he said.
"We can't say that this latest one isn't indicating something new is happening," Carpenter said. "But it seems like it's just a continuation of other small earthquakes that have happened in this area."
Most of the quakes have been small, but the two most powerful earthquakes ever recorded by instruments in Kentucky occurred in the Bath area in 1980 and 1988. They measured 5.1 and 4.6 respectively, Carpenter said.
"We're talking about a zone that's only about five miles long," he said.
Scientists aren't exactly sure why earthquakes happen in that area.
"Earthquakes are always related to a fault of some kind," Carpenter said. "But the funny thing is, ... there are no mapped faults that seem to correspond with where these earthquakes happened. There's obviously a fault, but you can't see it at the surface."