Minor earthquake rattles Columbia

March 11, 1993|By James M. Coram | James M. Coram,Staff Writer Staff Writers Douglas Birch and Sherry Joe contributed to this article.

No, Chicken Little, the sky was not falling -- even if it felt like it for a few seconds in Columbia yesterday morning.

Principal Linda Bates. "It felt like the gym floor lifted us up and dropped us down. It took a long time to calm the kids, especially the younger ones." The school has children from 4 years old to the eighth grade.

Some chips of cinder blocks fell down and some tracking that held up ceiling tiles fell to the ground, Ms. Bates said. Contractors looked at the damage and assured her it was not structural, she said.

Paul Evans, who lives on Stevens Forest Road in east Columbia about two miles from the epicenter, was working on a manuscript at his dining room table when he heard "a terrific boom sound -- as though an airplane had hit the building."

The rumble lasted about nine seconds, he thought. "If this is a mild dose, I don't want a big one," Mr. Evans said. "I called my insurance company to find out if my policy covers earthquake damage and they said, 'No.'

"But it does now."

Nearby, in the village of Owen Brown, 14-year-old Cara Baruth was sick with a cold when she was awakened by "a loud boom" she assumed to be caused by trash collectors.

"But the house started to shake" for about 10 seconds, she said. "It was weird. The pictures in my room are kind of crooked. I thought the picture over my bed was going to fall on my face, but it didn't."

In west Columbia, about three miles from the epicenter, Harper's Choice resident Carol Fleece "felt the house actually move."

"It was scary," she said. "I heard it. It was like a thud. My heart was pounding and I was thinking to myself, 'I hope that wasn't a bomb.' "

Despite the recent activity, Dr. James P. Reger, chief of the environmental geology program of the Maryland Geological Survey, said he doubts Maryland is headed into a period of more frequent earthquakes.

"I don't know of any seismologist who thinks we're on the verge of anything catastrophic," he said.

The strongest earthquake in state history occurred Nov. 26, 1939, in Phoenix, northern Baltimore County.

But it was still relatively small, the equivalent of about a 4.0 on the Richter scale, Dr. Hays said. That's the level in this region where the shaking would begin to crack plaster, break windows and send dishes crashing to the floor.

Dr. Hays said the recent earthquakes indicated that there is a moderately active fault zone or zones south and west of Baltimore. But Dr. Reger said that geologists really don't know what causes East Coast earthquakes, and that they may not be linked to fault activity.

The recent Columbia-area earthquakes, he said, might have been triggered by loose sediments sliding over bedrock 2,000 to 3,000 feet beneath the surface. Or they may be the result of a combination of other forces.

"Moderate" earthquakes register between 5.0 and 5.9 on the Richter scale. "Large" earthquakes weigh in at 6.0, and "major" earthquakes at 7.0. The justly feared "great" earthquakes, like the one that killed 6,000 people in Mexico City in 1985, start at 8.0.

The Richter scale increases logarithmically. A 3.5 earthquake is 30 times more powerful than a 2.5. A 4.5 is 900 times more powerful than a 2.5. And a 5.5 is 27,000 times more powerful.

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