A series of explosions at the Army's Aberdeen Proving Ground yesterday rattled dishes and startled residents from Perry Hall to Middletown, Del., 30 miles away.
"The entire house shook," said Joseph MulQueen, who called The Sun from his home in Perry Hall to report what he thought was an earthquake.
A check of area seismographs revealed no tremors. But officials at Aberdeen acknowledged that a series of afternoon blasts in the facility's Edgewood area did trigger about 30 phone calls.
The explosions were "static detonations," not shots from big guns, said George Mercer, the proving ground's chief of public affairs. "And they were loud. Anybody who took notice, who was disturbed or upset, had reason to be." He said one call he received was from Middletown, Del.
MulQueen was astonished to learn the source of the shaking he felt from 10 miles away. "Wow!" he said. "That is amazing."
The loudest of the three shots registered 129.3 decibels on one of the 18 noise monitors deployed around the installation. The Army's noise limit at those monitors is 130 decibels.
The impact of the big blasts was probably amplified by an atmospheric inversion over the region yesterday, Mercer said. That occurs when a layer of warm air lies on top of a surface layer of colder air. It tends to cause noise from proving ground tests to bounce back toward the ground rather than dissipate upward into the sky.
"This was not a happy day for that kind of thing," he said.
The public affairs chief said he could not reveal the nature of the tests, for security reasons.
"But when you're shooting things off and blowing things up, you're going to create noise," he said. "Today, the people making the decision to do it felt they really had to do it now. It was not something they could put off till later in the day, or later in the year. ... And we believe what we're doing is important."