New fault line discovered in New Jersey may explain unusual shaking from April’s 4.8 earthquake

PALISADES, N.Y. — The discovery of a new fault line could explain the unusually strong and displaced shaking. The 4.8 magnitude earthquake that hit the heart of New Jersey in Aprilbut it was felt most strongly many kilometers from the epicenter, A new research study shows.

The earthquake occurred late in the morning of April 5. New Jersey‘s Tewksbury County. However, the earthquake sent shockwaves to New York City, 40 to 50 miles away, and caused some damage in Brooklyn and New York. newarkNew Jersey.

It was the strongest earthquake in the region since 1884, shaking about 42 million people, according to U.S. Geological Survey estimates. USGS says 184,000 people reported feeling the earthquake — a registration number to fill out the report.

THE STRONGEST NEW JERSEY EARTHQUAKE IN 240 YEARS WAS FELT IN THE CITY OF NEW YORK IN THE NORTH EAST.

But researchers who went to the epicenter were surprised to find that the shaking was minimal and no noticeable damage was reported.

“We expected some property damage; chimneys toppled, walls cracked or plaster falling off, but there were no obvious signs,” the study’s co-author said. Wong Young Kim From the Columbia Climate School’s Lamont-Doherty Earth Observatory he said in a press release announcing the study results.. “We talked to the cops, but they weren’t too excited. It was like nothing had happened. It was a surprising reaction for a 4.8 magnitude earthquake.”

Shake intensity map from the USGS of the 4.8 magnitude earthquake that hit New Jersey on April 5, 2024.

(FOX Weather)

Kim’s study said that based on current models, the earthquake should have caused significant damage at the epicenter. Surface movement caused by earthquakes is measured at 10 points Modified Mercalli Density Scale, This earthquake should bring Level 7, or “very strong,” shaking within 6 miles of the epicenter, Kim said.

But no one at or around the epicenter reported the tremor’s intensity as 7 or anything close to it, according to the statement. Damage was limited to small cracks in some drywall and a few items falling off shelves.

But instead, three row houses in Newark, about 20 miles away, were damaged and New York City residents reported shaking equal to level 4 on the Mercali scale, and minor damage was reported to approximately 150 buildings. Equal new hampshire Level 3 was rocking about 280 miles away, the statement said.

“So it’s very hard to understand why a lot of people in the Northeast felt it, but far fewer people as far south as Philadelphia and further south as far as Virginia felt it, a lot less than people in the Northeast,” Kim told FOX Weather on Friday. ” he said. “There is also very little damage in the epicenter area.”

Earthquake waves went in different directions

Who says something typical earthquake It sends most of its energy directly to the surface, often making the epicenter the most dangerous place possible.

But in this case, the energy was sent downward until it reached the boundary between the Earth’s crust and mantle, about 20 miles underground. There the wave of energy bounced back and emerged beneath the New York City area for the massive tremor there.

Three homes were evacuated in Newark, New Jersey, following the 4.8 magnitude earthquake that shook the area on April 5, 2024.

(FOX 5 NY)

After another downward cycle, the wave reemerged slightly weaker. new englandWe repeat the cycle until the energy runs out.

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

Speaking to FOX Weather, Kim said, “In this case, at the 45-degree slope of the fault, the energy was directed towards the northeast and deeper.”

Northeast earthquakes are different from California tremors

Unlike rattling earthquakes California They are relatively frequent and caused by moving tectonic plates on the West Coast, while the Northeast earthquakes are remnants of ancient fault zones dating back 200 million years, the researchers said.

According to the study, at that time the region that is now Europe broke away from North America. Some areas are still settling and rearranging after all these years, occasionally triggering earthquakes.

Kim’s colleagues have calculated that an April-magnitude earthquake occurs about once every 100 years, but they suggest that the region could experience magnitude 6 earthquakes every 700 years and magnitude 7 earthquakes every 3,400 years.

“No one knows whether such earthquakes have occurred in human time,” wrote Kevin Krajick, author of the press release. “But if anyone did that, it would be a disaster.”

After the quake, researchers deployed a makeshift network of dozens of seismometers near the epicenter to measure dozens of subsequent aftershocks, hoping to better map faults in the area.

New Jersey earthquakes and aftershocks of the 4.8 main earthquake on April 5, 2024.

(FOX Weather)

The data could trigger the need to reassess how future earthquakes will affect the populous Northeast.

“Some earthquakes that are not that large may focus energy toward population centers,” Kim said. “If the (April) earthquake had been a little stronger or a little closer to New York, the impact would have been much greater. We need to understand this phenomenon and its consequences for ground motion prediction.”