Whole Lotta Shakin’ Goin’ on in Georgia : Earthquakes: Suburban Atlanta has been trembling since June, when a series of small temblors began. Seismologists insist it’s just water seeping through the granite, not a seismic fault.

The agent laughed when Jerry Bare bought earthquake insurance for his convenience store. Rural Georgia, after all, doesn’t exactly rumble like California.

But these days it’s shaking, with small temblors east of Atlanta rattling shelves and scaring residents.

Seismologists say not to worry. The shakes are caused by water seeping through the granite below Georgia’s red clay, not by seismic fault. But Bare isn’t taking chances.

“If a bad one does come, what are you going to do to stop Mother Nature?” he asked recently, a day after a 2.7 quake rattled his store. “We just wanted to cover ourselves.”

Mention Georgia and earthquakes in the same sentence and people are likely to snicker.

But towns all over the state have had earthquakes. The biggest was in 1974; it registered 4.5 on the Richter Scale and was centered near Augusta.

“We don’t really have any areas that rock and roll,” said Ken Davis of the Georgia Emergency Management Agency. “But, yeah, we do have an earthquake thread in Georgia.”

That became apparent in June, when residents of Norris Lake outside Atlanta felt split-second shakes, the kind that occur when thunder booms directly overhead or a train speeds by.

They figured it was blasting from a granite quarry.

Then a seismologist delivered stunning news: Up to 70 small earthquakes were occurring every day under Norris Lake, a 20-acre, man-made lake built in the 1930s.

Most were too small to feel, but when 10 temblors measuring 2.0 to 2.5 occurred from June into August, frightened residents besieged officials with questions.

“I didn’t understand how this could be happening all of a sudden,” said Terri Norton, a 12-year resident of the area. “It’s scary to see your dishes start rattling all of a sudden for no apparent reason.”

Experts urged calm. The devastating 7.1 earthquake in San Francisco in 1989, for example, was 100,000 times more powerful than the worst at Norris Lake.

Typically, earthquakes cause no serious damage until they reach a strength of 5.5. A quake of magnitude 2 is the smallest normally felt by humans; a quake of 3.5 can cause slight damage. But a few Norris Lake residents report cracks in their driveways or broken windows, and insurance agents are fielding dozens of requests for earthquake policies.

Water seeping through granite half a mile under the red clay is causing the rock layers to shift, says Georgia Tech seismologist Tim Long, who is tracking the temblors. Anything from quarrying to erosion can trigger them.

Big quakes originate from active faults about five miles underground.

Long has detected similar “swarms” of seepage-caused quakes at the state’s largest lakes.

“I expect these have peaked, but I don’t want to say a larger one couldn’t occur,” he said, “because it is possible.”

That’s what worries Bare.

“So far it’s just rattling the windows and knocking things off the shelves,” he said from his business, Ms. Jean’s Country Store, where the locals gather to swap earthquake tales.

“But it’ll scare you when it starts rumbling.”