Reports of tremors in Connecticut, New Jersey related to sonic booms from military jets

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HAMMONTON, N.J. — Tremors shook parts of the Northeast Thursday afternoon. The U.S. Geological Survey, which assesses earthquakes, reports there was not an earthquake, and the shaking was actually a series of sonic booms in southern New Jersey, which were caused by a military fighter jet conducting tests. The booms started occurring at 1:24 p.m. and lasted about 90 minutes.

A sonic boom is caused by shock waves from an object traveling faster than the speed of sound and breaking the sound barrier. The reason some felt it later than others is because the shock waves travel with the object, so it hits the ground at different locations at different times.

Navy spokeswoman Connie Hempel says an F-35C from Naval Air Station Patuxent River, Maryland, was conducting supersonic testing off the east coast Thursday afternoon.

The jet has a top speed of nearly 1,200 mph.

She said that supersonic test flights are conducted almost daily in the same area, but that most sonic booms aren’t felt on land. Certain atmospheric conditions can increase the chance of hearing the booms.

But how could people in Connecticut feel tremors from a sonic boom all the way off the coast of Southern New Jersey??

One explanation is a temperature inversion! Instead of sound spreading out in all directions, sometimes it can get trapped close to the ground. This same set up can also lead to poor air quality days, trapping ozone, dirt and pollen near the ground. It can also help radio and TV signals travel farther than usual (also called atmospheric ducting).

People in Madison, Guilford, Norwalk and other Connecticut shoreline towns felt the tremors, and many wondered if it was an earthquake.

Additional reporting by the Associated Press.