Some thought it was the patter of little feet. Others weren't sure what the rattling was.
In fact, even after learning there was a minor earthquake Saturday at 7:27 a.m. in Northwest Baltimore County, some residents still were not sure whether they had felt it.
"We may have felt it," said Brenda Cohen, who lives in Randallstown, the quake's epicenter. "We heard a noise. My husband turned on the radio and said, 'That must have been the noise we heard.' It sounded like something was running in our house."
Steve Quinn, also of Randallstown, was still in bed when the shaking started.
"Now that you mention it . . . I remember hearing something, but it wasn't much," he said last night. "I heard a noise. I thought maybe one of the kids fell down."
The temblor registered a paltry 2.4 on the Richter scale, according to the National Earthquake Information Center at Golden, Colo.
"That's very small, of course," said Don Finley, a spokesman for the U.S. Geological Survey in Reston, Va. "A lot of people wouldn't even feel that. There certainly wouldn't be any damage from it."
And that, in fact, was the case. The Baltimore County police said there were no reports of damage or injuries from the quake. Baltimore Gas and Electric Co. officials said the temblor caused no problems with electric or gas lines.
This sure isn't San Francisco.
The quake was probably caused by slippage along one of the many minor faults that crisscross Maryland, said David Russ, a geologist with the U.S. Geological Survey.
"Most of the earth's crust has faults, some more active than others, some larger than others," Mr. Russ said. Most of the them are fossil faults which are the result of ancient breakages in the earth's crust. Most of the faults in Maryland are inactive, but some still cause seismic activity.
There have been dozens of small earthquakes recorded in Maryland. A quake of damaging magnitude, which are those above 4 or 5 on the Richter scale, is extremely rare on the East Coast but is always a possibility, Mr. Russ said.
Baltimore had a major earthquake in 1883, and the worst East Coast quake, which heavily damaged Charleston, S.C., in 1886, killed 38 people.
But an earthquake of any magnitude, even one that would not interrupt a conversation in California, will get attention in Maryland. "Because people haven't experienced it before, they get excited about it," Mr. Russ said.