PALISADES, NY — The discovery of a new fault line may explain the unusually strong and displaced shaking from The April 4.8 earthquake that struck the heart of New Jerseyhowever it was felt most strongly miles away from the epicenter, a new research study shows.

The earthquake occurred on April 5, in the late morning, in the center New JerseyTewksbury Township. But the earthquake sent shock waves through New York City 40-50 miles away and caused some damage in Brooklyn and NewarkNew Jersey.

It was the region’s strongest earthquake since 1884, uprooting an estimated 42 million people, according to US Geological Survey estimates. The The USGS said 184,000 people reported feeling the quake — a registration number to complete the report.

NEW JERSEY’S STRONGEST EARTHQUAKE IN 240 YEARS FELT IN NEW YORK CITY, NORTHEAST

However, researchers who went to the epicenter were puzzled to find that there was very little shaking and no perceptible damage was reported.

“We expected some material damage – collapsed chimneys, cracked walls or falling plaster, but there were no obvious signs,” co-author of the study. Wong-Young Kim of the Lamont-Doherty Earth Observatory at Columbia Climate School said in a press release announcing the study results. “I spoke to the police officers, but they weren’t too happy about it. Like nothing happened. It was a surprising response for a 4.8 magnitude earthquake.”

A USGS map of tremor intensity from a 4.8 earthquake that struck New Jersey on April 5, 2024.

(FOX Weather)

Kim’s study said that based on existing models, the earthquake should have caused substantial damage at the epicenter. The surface motion generated by the earthquake is measured on 10 points Modified Mercalli intensity scale, and this earthquake should have caused magnitude 7 or “very strong” tremors 6 miles from the epicenter, Kim said.

However, no one at or around the epicenter reported tremors of magnitude 7 or anything close to it, according to the statement. Damage was limited to minor cracks in some drywall and a few items thrown from shelves.

But instead, three townhouses were damaged in Newark, about 20 miles away, and New York City residents reported shaking equal to a level 4 on the Mercali scale and about 150 buildings reported minor damage. Even New Hampshire reported a level 3 tremor about 280 miles away, the statement said.

“So it’s very puzzling why a lot of people felt it in the Northeast, (but) far fewer people felt it as far south as Philadelphia and as far south as Virginia — far less than people from the northeast,” Kim told FOX Weather on Friday. “As well as very little damage around the epicenter area.”

The earthquake waves went in a different direction

Kim says a typical earthquake it would send much of its energy directly to the surface, which usually makes the epicenter the most dangerous place.

But in this case, the energy was sent down until it reached the boundary between the Earth’s crust and mantle, about 20 miles underground. There the wave of energy returned, coming out under the New York area for the big shake there.

Three homes were evacuated in Newark, New Jersey after a 4.8 magnitude earthquake shook the region on April 5, 2024.

(FOX 5 NY)

After another down cycle, the wave reappeared a little weaker New Englandrepeating the cycle until the energy dissipated.

Kim’s team’s analysis suggests the earthquake occurred on a previously unmapped fault that runs south to north. But unlike traditional faults that run vertically, this one dips eastward into the Earth at an angle of about 45 degrees, sending energy in unusual directions.

“In this case, on the 45-degree dip of the fault, the energy went northeast and down,” Kim told FOX Weather.

Northeast earthquakes differ from California earthquakes

Unlike earthquakes that rattle California and West Coast with relative frequency and are caused by moving tectonic plates, earthquakes in the Northeast are left over from ancient fault zones stretching back 200 million years, researchers said.

That’s when what is now Europe broke away from North America, the study shows. Some areas are still settling and readjusting all these years later, triggering the occasional earthquake.

Kim’s colleagues calculated that an earthquake of April’s magnitude occurs about once every 100 years, but suggest that the region could see a magnitude 6 earthquake every 700 years and up to a magnitude 7 every 3,400 years.

“No one knows if such earthquakes have occurred in human time or could,” wrote Kevin Krajick, author of the press release. “But if they did, it would be catastrophic.”

In the aftermath of the earthquake, researchers placed a temporary array of dozens of seismometers near the epicenter to measure the dozens of aftershocks, hoping to better map the region’s faults.

Earthquakes and aftershocks in New Jersey from the 4.8 main earthquake of April 5, 2024.

(FOX Weather)

The data may trigger the need to reassess how future earthquakes would impact the population of the Northeast.

“Some (earthquakes) that are not even that big could concentrate the energy towards population centers,” Kim said. “If the (April) earthquake was just a little bit stronger or a little bit closer to New York City, the effect would be much greater. We need to understand this phenomenon and its implications for ground motion prediction.”