Another quake rattles NJ; one of strongest aftershocks since early April 4.8 earthquake

Jenna Calderón, Asbury Park Press

Another earthquake rattled New Jersey early Friday — one of nearly 180 aftershocks that have struck since the 4.8 quake rumbled New Jersey in early April, according to authorities.

At 3:50 a.m., an aftershock with a magnitude of 2.9 — one of the strongest since the initial incident on April 5 — rattled Gladstone, raising the total aftershocks to 177, the United States Geological Survey said.

The April 5 magnitude 4.8 quake, which hit at 10:23 a.m., ranks as the second most powerful to hit New Jersey going back to 1783, when the north-central part of the state saw a magnitude 5.3 trembler, according to the New Jersey Office of Emergency Management.

David Robinson, physical geographer at Rutgers University, said he believes Friday's quake is more than likely associated with the April 5 quake.

"The rocks along the Ramapo Fault are old," Robinson said. "They're very brittle and they got the shake of the century back on the fifth. So, it stands to reason that it's going to take them a little while to quiet down."

Months from now, it would be difficult to call something an aftershock, Robinson said. But six weeks after the initial event and in the same fault complex, it's not surprising.

Robinson said the initial 4.8-magnitude quake was unusually strong for the earthquakes that happen in our region.

Timothy Clements, spokesperson for the U.S. Geological Survey, said Friday's earthquake should temporarily increase the rate of small aftershocks, or aftershocks at or less than a magnitude of two.

"Small aftershocks will continue over the next few months to year, with the rate of felt aftershocks, such as today’s, decreasing over time," Clements said.

The survey's most recent forecast for the area suggests that there is about a one in 25 chance of a M4+ earthquake occurring in the next year, Clements said.

"The chance of a damaging earthquake occurring in the next year is less than one percent," he said.

Earthquakes of a 4.8 magnitude are expected to have this many aftershocks, according to Clements, but this aftershock sequence is decaying faster than previous aftershock sequences.

The Garden State sees multiple earthquakes a year, but some of them are at levels that cannot be felt, or are only felt very locally.

Before the April 5 event, there was an foreshock with a 2.2 magnitude on March 15 near Whitehouse Station in Hunterdon County, according to the U.S. Geological Survey. Prior to that, the last earthquake in New Jersey was a 1.7-magnitude that occurred near the Lake Telemark section of Roxbury Township in Morris County in August 2022, according to the survey.

New Jersey is within a lithospheric plate, not on a plate boundary where earthquakes are common, Robinson said. The nearest plate boundaries are in the middle of the Atlantic Ocean, in the Caribbean and in southern California, so the early April event is considered an intraplate quake.

One of the strongest earthquakes at the Jersey Shore was a magnitude 3.8 quake that struck near Freehold on January 30, 1979.

There have been other earthquakes at the Jersey Shore: a 2.2-magnitude at Tuckerton in June 2021; a 3.1-magnitude near Marlboro in September 2020; and a 1.4-magnitude that occurred near Keansburg in August 2017.

On Aug. 8, 2011, there was a 5.8 magnitude earthquake with an epicenter in central Virginia that was felt more strongly in New Jersey than the quake in April. In 2011, ceiling tiles fell at a Sears store in Middletown, and there were evacuations of high rises, hospitals, schools, casinos, and hotels in Atlantic City, according to the state OEM.

Here's a list of the aftershocks that have hit the Garden State in the last week:

  • 2.9 magnitude; 6 km WSW of Gladstone, New Jersey; May 24; 03:50:12 (UTC-04:00)7.0 km

  • 1.6 magnitude; 7 km ESE of Califon; May 21; 05:59:56 (UTC-04:00)6.3 km

  • 1.5 magnitude; 7 km W of Gladstone; May 18; 20:59:02 (UTC-04:00)9.8 km

  • 1.3 magnitude; 6 km ESE of Califon; May 17; 21:41:05 (UTC-04:00)5.3 km

  • 1.2 magnitude; 6 km ESE of Califon; May 17; 11:28:38 (UTC-04:00)

This article originally appeared on Asbury Park Press: Was there an earthquake today? Yes, in Tewksbury NJ

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