A small earthquake shook a New Jersey community Thursday evening, prompting concerned residents to call 911.
The U.S. Geological Survey confirms a shallow 1.6-magnitude earthquake was measured in Butler in Morris County. The epicenter was next door in Bloomindale, but Butler police got most of the calls.
Butler police said it was flooded with over 1,000 calls and online messages.
In one call, provided exclusively to NBC 4 New York, a dispatcher reference the rush of calls about the rumble.
"My house shook like crazy in Butler," the caller said.
"Yep, so did everybody else's," the dispatcher replied. "We're trying to find out what it is, ma'am."
Another caller asked the dispatcher to call her back when police found out what caused the rumble.
"Um, ma'am honestly, I have 100,00 calls I've been dealing with all night," the dispatcher replied.
Not quite that many, but there were a lot.
Ricardo Rico was at his home in Butler when he felt his house shake. He said he wasn't sure what the rumble was at first.
"I wasn't scared because we've had little earthquakes like this before. But I was like, 'What is this?' I honestly thought my upstairs neighbor fell and I was worried."
Rico said he was nervous until he got on Facebook and saw his friends talking about the earthquake.
No damage was reported.
Any earthquake with a magnitude of 1.0 to 3.0 is lowest in the scale of Modified Mercalli Intensity, according to the USGS: it's typically not felt except by a very few under especially favorable conditions.
It may have been felt more widely in this case because the earthquake was so shallow — the epicenter was about a mile underground on the Ramapo Fault, according to the Morris County sheriff.
Seismologists at Columbia University's Lamont-Doherty Earth Observatory say that the tectonic plate bordered by the Mid-Atlantic Ridge is moving an inch a year toward New York and New Jersey. The pressure has resulted in five small earthquakes across the tri-state in little more than a year.
Last month, tri-state residents reported feeling rumbles that were later determined to be sonic booms caused by naval aircraft testing over the Atlantic Ocean. Those were not seismic.