Patrons and employees of the Bagel Bin in downtown Bernardsville told NJ Advance Media they felt the earthquake early Friday morning, but no one said they'd sustained any damage to their homes or been injured.
Rich Green, a customer, said the earthquake shook his Mendham Road house, which was near the epicenter of the quake.
"It was a huge boom," he said. "The ground was shaking. My wife thought it was thunder, I thought it was some type of explosion."
Abby Chernin, a Bagen Bin employee, said she hadn't heard the earthquake, but her husband had jumped out of bed because of it.
Chernin said she asked her husband, "Are you going to make sure we weren't being robbed?" But, she said, then they realized what had actually happened.
Sari Mazen, another employee, said she, too, had initially thought it was thunder. Mazen said this was her second New Jersey earthquake in recent memory, the last occurring more than two years ago while she was on a beach in Belmar.
Benardsville, Nj Had a 2.5 magnitude earthquake after sounds of an explosion...
— Erick (@letmeexplainit) August 14, 2015Ruth Levin, who lives in West Orange but works at the Bagel Bin, said her dog began acting very strangely at about 12:30 a.m.
"The dog was pacing back-and-forth, very neurotic, she'd never been like that before," Levin said. "She was frightened and stayed next to me all night."
As noted by the U.S. Geological Survey, anecdotal evidence dating back thousands of years refers to animals acting strangely anywhere from weeks to seconds before an earthquake strikes.
The Morris County Communications/911 center received calls from residents in Morristown, Morris Township, Randolph, Mendham Township, Mendham Borough, Chester Township and Chester Borough, spokesman Jeff Paul said.
There have been no reported injuries nor damage to homes or businesses.
Won-Young Kim, a seismologist with Columbia University, said the earthquake had occurred about two-and-a-half miles from Bernardsville on a "polar fault" which is an offshoot of the main Ramapo fault.
"These faults are not active nowadays," said Kim, who is also a member of the Lamont-Doherty Cooperative Seismographic Network. "This small earthquake, 2.7, doesn't involve miles of fault line."
"It's probably one-quarter mile or much less, such as a hundred yards."
The LDCSN operates in the northeastern U.S. and cooperates with the USGS, he said. A seismological recording station is set-up at William Annin Middle School in Bernards Township, about four miles away from where the earthquake occurred, so the network has been able to determine the location fairly well, Kim said.
The earthquake, he said, occurred at about a depth of two miles which is "very shallow."
"I don't expect damage, maybe some houses very close would have items falling from shelves," he said. But, Kim said, it is possible for some residents to have heard sounds waves emanating as a result of the quake.
Rutgers Geology Professor Alexander Gates said residents of New Jersey are typically more likely to hear an earthquake than people in California because Garden State quakes occur closer to the surface.
"Pressure builds on the fault with time and at a certain point it becomes stronger than what the rock can hold," Gates said. "If the earthquake is shallow enough, then you can hear the rock breaking."
In December, a 1.7 magnitude earthquake was centered 17 miles east/southeast of Trenton. A 2.0 earthquake in Nov. 2012 hit around Ringwood.
NJ Advance Media staff writers Kimberly Redmond and Jeff Goldman contributed to this report.
2.5 magnitude earthquake is hardly felt let alone shake a house.
Most probably this was something else that caused a sound like an explosion.