"What was that?" was the question that rumbled through a large swath of North Jersey and into New York State early Wednesday afternoon.
Mine blasting? A sonic boom? Seneca guns?
Unconfirmed reports of an earthquake or "seismic-like event" stretched from Newton and Sparta in Sussex County to as far east as the Palisades in Alpine beginning at 12:52 p.m. Jan. 11.
There were similar calls in several southern New York State counties, as well as in the Poconos in Pennsylvania.
All are basically in the area of the Ramapo Fault Line. The longest and oldest in the Northeast -- at 185 miles and 200 million years -- it begins in Pennsylvania and heads through northeast Hunterdon, Somerset, Morris, Passaic and Bergen counties before reaching Westchester.
Dispatchers in various North Jersey towns fielded calls from concerned residents and merchants on Wednesday. There were no complaints of damage anywhere, however, according to police.
The U.S. Geological Survey hadn't reported any area events during the day.
The boom was quick and short. But it made an impression.
"Sounds like an earthquake," Kim Griggs of Emerson wrote, as social media itself erupted in posts and comments.
"Felt like something very heavy fell and hit the ground," Ed Bueti of Emerson said.
"Sounded like a tree fell on the house," said Tom Desmond of Washington Township.
"No clue what it was," Lisa Schrader Clark of Paramus responded. "Scared the crap out of my dog. Shook my house."
"I was sure I was going to hear sirens and so surprised I didn’t," Eileen Kempton added.
Although police in Morris County's Jefferson Township had warned earlier that Mount Quarry would be blasting on Wednesday, seismologists have said there wouldn't be any possible connection.
"Even huge amounts of explosives almost never cause even small earthquakes," the USGS reports.
That didn't stop people from wondering.
Daily Voice readers reported hearing and/or feeling the boom in, among other locations, Allendale, Bergenfield, Clifton, Dumont, Demarest, Franklin Lakes, Glen Rock, Hackensack, Harrington Park, Ho-Ho-Kus, Hillsdale, Mahwah, Midland Park, Norwood, Oakland, Oradell, Ridgewood, Ringwood, River Vale, South Hackensack, Waldwick, West Milford, Westwood and Woodcliff Lake.
"Sounded like a semi hit something. Scared my cats," Alicia White of Waldwick wrote.
"NASA was expecting an uncontrolled entry of a satellite, but that was Monday," Jay Burd offered.
"Heard a loud noise and a weird sensation," wrote Jane Farelli of Maywood. "Thought something blew at [the] gas station on [the] corner."
TJ Sullivan of Saddle Brook was among those amused by the reactions.
"Everyone’s talking about it… and no one knows what it was," he wrote.
Leave it to the experts to throw cold water on the exercise. According to the USGS:"Reports of unidentified 'booms' have emerged from different places around the world for hundreds of years, and although many of the “boom stories” remain a mystery, others have been explained. Most of the booms that people hear or experience are the result of human activity, such as an explosion, a large vehicle going by, nearby construction, or sometimes a sonic boom, but there have been many reports of booms that cannot be explained by man-made sources. Some of those booms are associated with a variety of interesting natural phenomena, including earthquakes."
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