Was the Ramapo Fault to blame for N.J.’s earthquake?
New Jersey Online
BERNARDSVILLE — While Friday morning’s 2.7-magnitude earthquake was the 189th to rattle the Garden State since 1783, it was far from the largest or most destructive, officials said.
The largest earthquake to shake New Jersey in recent history had a magnitude of 5 and was centered under western Long Island in 1884, according to state Department of Environmental Protection spokesman Larry Hajna. That earthquake reportedly caused damage to structures in New Jersey.
In more recent history, a 1.7 magnitude earthquake was centered 17 miles east/southeast of Trenton this past December while a 2.0 earthquake in Nov. 2012 hit around Ringwood.
Based on the U.S. Geological Survey’s Community Intensity Internet Map, Friday’s earthquake was felt as far north as West Milford and as south as Princeton.
Won-Young Kim, a seismologist with Columbia University, said the earthquake had occurred about two-and-a-half miles from Bernardsville on an offshoot of the main Ramapo Fault System.
The Ramapo Fault is a “very old” fault running northeast, but Friday’s seismic activity occurred in one of the “crisscrossing” smaller faults running northwest, said Kim, who is also a member of the Lamont-Doherty Cooperative Seismographic Network.
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.
“These faults are not active nowadays,” he said. “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 Ramapo Fault is part of a system of faults that runs from southeastern New York to eastern Pennsylvania. According to a 2004 fact sheet by Columbia University, these faults were active “during the evolution of the Appalachians, especially in the Mesozoic when they served as border faults to the Newark Basin and other extensional basins formed by the opening of the Atlantic Ocean approximately 200 million years ago.”
“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.”
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.
Ruth 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.
Bernardsville residents at the local ShopRite told NJ Advance Media also said their first thought wasn’t that an earthquake had happened.
Susan Diegnan from Bernardsville said she and her husband both woke up because they thought a tree might have fallen.
Pattie Dolan, a Shop Rite employee who lives on Liberty Road, said her son and daughter slept through the earthquake but her cats “were going crazy” during the quake.
“I jumped out of bed and my whole house was shaking,” she said. “It felt like a train hit my house.”
Despite the tremors, Dolan said she fell back asleep in 20 minutes.