What's Causing the Booms Heard Around Philly? - NBC New York

What's Causing the Booms Heard Around Philly?

The National Weather Service told NBC10 Tuesday that the booms may have been caused by frost quakes.

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    NEWSLETTERS

    More Mystery Booms in Philly

    Last week, there was a mysterious boom heard from South Philly to South Jersey. Late Monday night, people took to social media to report that they heard a boom again. Investigators still do not have possible causes for the sounds.

    (Published Tuesday, Feb. 5, 2019)

    For the second time in a week, Philadelphians are asking, what went boom in the night?

    Just like last Tuesday, a loud noise, or noises, just before 11 p.m. Monday night caused people to turn to social media to ask what it was. People described it as a boom, louder than a firework.

    This time, some people claimed to hear a series of loud noises.

    NBC10 reached out to Philadelphia firefighters and police but they didn’t know of a source of the sounds that were heard from South Philadelphia to Spring Garden.

    The National Weather Service told NBC10 Tuesday that the booms may have been caused by frost quakes.

    Frost quakes, also known as Cryoseism, are loud, booming or cracking sounds that occur when large amounts of water freeze quickly underground and then rapidly expand. The soil and rocks underground are forced apart by the expanding water and lead to the booming sound.

    "This is a natural phenomenon that happens after a fast, deep freeze like we experienced several times in the past few weeks," NBC10 First Alert Weather chief meteorologist Tammie Souza wrote.

    Yet while the National Weather Service named frost quakes as the possible cause of the booms, it has not yet been confirmed.

    Last week’s boom was heard as far away as New Jersey. This week’s boom seemed more confined. People’s theories covered everything from a meteorological event to a firework from the Midnight Lion Dance celebration for Chinese New Year’s in Chinatown.

    Just like last week’s boom, the U.S. Geological Survey had no reports of an earthquake in the area.

    The cause of last week’s boom was never determined.