A 4.0 magnitude aftershock rattled the northeast on Friday night only hours after the region experienced a rare 4.8 magnitude earthquake, and officials are warning that more could be coming soon.
The aftershock hit Gladstone, New Jersey, just before 6:00 p.m. ET on Friday, prompting many in the New York metro area to voice their disbelief over experiencing "another earthquake" on social media.
The U.S. Geological Survey (USGS) said that the larger earthquake—which centered on Whitehouse Station, New Jersey, at 10:23 a.m. ET—was the strongest felt in the area since 1950.
While some expressed confusion about the second earthquake, a USGS spokesperson told Newsweek via email on Friday night that it was "considered an aftershock to the M4.8 mainshock from earlier today."
"Aftershocks are earthquakes," the spokesperson said. "They are just smaller magnitude quakes that follow the largest quake, which is referred to as the 'mainshock.' The M4.8 this morning would be considered the 'mainshock' since it was the largest, while the M4.0 and others occurring after are called 'aftershocks.'"
"If a larger earthquake were to occur after the mainshock, then that new quake becomes the mainshock, and the earlier quakes become 'foreshocks,'" the USGS representative added. "Then things start again as subsequent smaller quakes following that new quake become aftershocks."
New York Governor Kathy Hochul wrote in a post to X, formerly Twitter, that a review of "critical infrastructure" was underway to determine the extent of any damage caused by Friday night's aftershock.
"A 4.0 magnitude aftershock from this morning's earthquake in New Jersey just occurred," Hochul wrote. "We are continuing to review critical infrastructure and there are no reports of significant damage at this time."
USGS officials have forecasted that there is a 78 percent chance of additional 3.0 magnitude or larger aftershocks striking the area within the next week. The chances of additional 4.0 or larger aftershocks are 16 percent.
The likelihood of 5.0 or stronger earthquakes hitting the area over the next week is only 2 percent, with the odds continuing to decrease as the magnitude of any potential quake increases.
The USGS model predicts that there is a 1 in 6,000 chance of the northeast experiencing a massive 7.0 magnitude or stronger earthquake over the next week, while the odds increase to 1 in 1,000 over the next year.
Several smaller aftershocks, resulting in vibrations small enough that people likely could not feel them, hit the area in the hours after the 4.8 quake and before the larger 4.0 aftershock hit.
The aftershocks were all closely grouped together in the same area. Gladstone, New Jersey—the location of the large aftershock—is located approximately 9 miles away from the epicenter of the 4.8 earthquake at Whitehouse Station.
While the likelihood of the northeast experiencing a major earthquake in the near future remains slim, public officials have warned residents to be prepared for the possibility.
Tips shared by New York's Division of Homeland Security and Emergency Services include securing furniture and appliances to avoid them tipping over during an earthquake and storing any dangerous household chemicals in secured cabinets to avoid spillage.
Read more: Emergency Funds: How to Build One and Where to Keep It
During an earthquake, officials suggest remaining indoors and taking cover under a sturdy object like a desk or a table, or at an interior wall. People who are outside during an earthquake should move into an open area and away from trees, buildings and other structures.
Update 04/05/24 9:09 p.m. ET: This story has been updated to include more information.
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Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.
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Aila Slisco is a Newsweek night reporter based in New York. Her focus is on reporting national politics, where she ... Read more
