How could the sonic booms on Thursday be heard over such a wide area?

Residents of New Jersey and several other states Thursday scrambled for information after feeling a series of tremors — intense enough that many mistook them for an earthquake after the first was reported in South Jersey shortly before 1:30 p.m.

Soon, reports started showing up on social media of not just one, but several tremors, felt from Ocean County down to the southern tip of the state. Then more reports came in — in Long Island, in Connecticut, and elsewhere. In all, about nine tremors were felt.

It wasn't until late afternoon that officials at the Naval Air Station Patuxent River in Maryland said the tremors — by then determined by the U.S. Geological Survey to have been sonic booms, not earthquakes — were likely caused by "routine flight testing" in the Atlantic Test Ranges, which span from New Jersey to North Carolina.

But the Naval station hasn't given any more detail about what sort of tests were being run, or how many aircraft they involved.

Heidi Koontz, a spokesperson for the US Geological Survey, said the survey doesn't normally deal with sonic booms, but investigated Thursday's incident after being inundated with phone calls.

Dr. John Bochanski, an assistant professor of physics at Rider University, didn't feel the effects on the Lawrenceville campus. But he said that the higher in the sky a plane hitting supersonic speeds travels, the larger an area would hear the boom — "which is why people up and down the state heard it."

According to the US Geological Survey, "a sonic boom travels through the air with the airplane so it arrives at different ground locations at different times."

Bochanski said an aircraft would need to reach 760 mph to create a sonic boom — any many military jets can.

Bochanski said that "if you were close enough to one you would feel it pass" — and a sonic boom could even cause structural damage, though there were no reports of significant damage Thursday.

"It has smaller symptoms of an earthquake, "Bochanski said. "You would feel a rumbling, hear something and maybe see a crack in the wall."

Bochanski had no information about Thursday's training, but said nine sonic booms could have been created by multiple planes — especially if they were heard back-to-back. At least some of the booms seemed to happen in rapid succession.

"Or you could have a plane that was exceeding 760 mph, turning around, slowing down and then speeding back up again and that would produce another sonic boom," Bochanski said.

Bochanski said that when has was teaching at a Florida school, sonic booms would occur when the Space Shuttle missions would land at Cape Kennedy 60 miles away.

"It was like a really loud clap of thunder" and created a shock wave, he said. He said residents knew to expect a sonic boom during landings.

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