4.0-Magnitude Aftershock Rattles NJ Hours After Earthquake

Additional aftershocks have the potential to occur over the coming weeks.

aftershocks in April 5 earthquake in NJ
Image: U.S. Geological Survey

New Jerseyans were shaken up once again on Friday night when a 4.0-magnitude aftershock hit the state roughly eight hours after a rare 4.8-magnitude earthquake.

The “notable” aftershock, as the U.S. Geological Service called it, occurred around 6 pm. It was the largest of a number of aftershocks reported throughout Friday.

The aftershock was centered in Gladstone in Somerset County. “New Jersey just experienced an aftershock,” Governor Phil Murphy wrote on X (formerly Twitter). “Please follow the emergency guidance below and avoid calling 911 unless you have an actual emergency.”

The initial quake, centered in Whitehouse Station in Hunterdon County (which is about 15 miles from Gladstone), occurred at 10:23 am. It was felt by millions of people in New Jersey and New York, and as far away as Maine and Virginia.

“Earthquakes in this region are uncommon but not unexpected,” Paul Earle of the USGS National Earthquakes Information Center said during a news conference on Friday.

On Friday afternoon, Sara McBride of the USGS Earthquake Hazards Program said there is a 3 percent chance of a magnitude-5 aftershock in the next week. The USGS reported a 38 percent chance of a magnitude-3 aftershock within the next week and a 9 percent chance of a magnitude-4 aftershock, like the one that hit New Jersey on Friday evening. 

Additional aftershocks have the potential to occur over the coming weeks.

In the event of an earthquake, people are advised to drop, cover and hold on, says the USGS.

New Jersey’s largest known earthquake struck in 1783, and is typically listed as 5.3 in magnitude. Over the last several decades, there have been “a number of” magnitude 4-6 earthquakes in this region, Jessica Thompson Jobe of the USGS Hazards Program said Friday. Magnitude-5 earthquakes have been reported just three times in the last few hundred years, according to Jobe.

New Jerseyans were certainly shocked by the quake, with residents taking to social media to share their disbelief (and a lot of funny GIFs). “We thought the dryer downstairs was off-balance, but then there was more shaking of the whole house and louder rumbling,” one person commented on Facebook. “A few things fell off a shelf and my oldest son yelled ‘Earthquake- get out!’ Very scary!”

“Plates flew out of my closed kitchen cabinets,” another person wrote.

Former Governor Chris Christie, who lives about 20 miles from Whitehouse Station, wrote on X, “A few moments ago our entire house shook for about 25 seconds or so here in Mendham, NJ. Did we just have an earthquake?”

Governor Murphy was just as surprised as the rest of us when the shaking started. “Who saw a pandemic coming four years ago? Who saw an earthquake coming this morning? You live and learn,” he told CBS News New York on Friday. He says officials will “do a full post-mortem” to assess the situation.

On Friday after, the USGS said the organization couldn’t yet attribute this quake to a specific fault, as scientists were still investigating. Northern New Jersey straddles the Ramapo Fault, the longest fault in the Northeast. The fault begins in Pennsylvania and moves into New Jersey, trending northeast through Hunterdon—where Friday morning’s earthquake was centered—as well as Somerset, Morris, Passaic and Bergen counties before ending in New York’s Westchester County.

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