People on the East Coast of the United States on April 5, 2024 experienced an unusual earthquake. Three homes partially collapsed in Newark, New Jersey. Minor damage was reported to approximately 150 buildings in New York. Sinkhole opened on Long Island and people have noticed the vibrations as far away as Virginia, New Hampshire, and Maine. US Geological Survey (USGS), earthquake Felt by approximately 42 million people.

However, in New Jersey’s Tewksbury County, the epicenter of the 4.8 magnitude earthquake, residents felt almost no shaking.

The study’s co-author noted that while scientists were “very confused” about why people were experiencing the earthquake in such remote locations, “they saw very little damage in the epicenter area.” Won Young KimThe researcher from the Columbia Climate School’s Lamont-Doherty Earth Observatory says: FOX WeatherScott Sistek. Now, a new study published this fall Seismic Recording offers an explanation.

In “normal” earthquakes, the shaking is felt most intensely at the epicenter, that is, at the point on the Earth’s surface just above the earthquake. focusor hypocenter, the place where earthquakes begin in the planet’s ever-changing crust. Shaking usually radiates outward from the focal point in a bull’s-eye pattern.

Models based on the magnitude of the April quake, its relatively shallow depth of 4.5 miles, and the geology of the region suggest that a roughly six-mile area around the epicenter should have felt the quake’s magnitude VII tremor. Modified Mercalli Density Scale—a level described as “very strong.”

But that’s not what happens. Although the region has been hit The biggest earthquake since 1884But hours later, when the research team went to investigate the epicenter, it didn’t look like that.

“We expected some property damage; chimneys toppled, walls cracked or plaster falling off, but there were no obvious signs,” Kim said. expression. “We talked to the police officers, but they weren’t too excited about it. It’s like nothing happened. “This was a surprising response for a 4.8 magnitude earthquake.”

The team conducted analysis to understand what happened lg waves Earthquakes are low-frequency energy waves that bounce back and forth between the Earth’s surface and the boundary between our planet’s crust and mantle. moho. The analysis found a previously unknown fault running south to north and bending eastward at an angle of approximately 45 degrees, according to the statement.

Scientists concluded that the motion that caused the earthquake was rapid and complex, combining two motions; While the horizontal sliding of the two sides of the fault was called “strike slip”, there was a movement called one side passing over the other. a “push”. While energy from earthquakes normally moves towards areas of least pressure, such as towards the surface at the epicenter, this time was different. The team proposes that the energy follows the fault line downward, bouncing off the Moho and surfacing in places like New York City, then bouncing down and back up again, hitting more distant areas.

Earthquakes on the East Coast are rare, especially compared to the West Coast, which is much more seismically active. However, the former is felt more widely due to geological differences between regions. The East Coast consists mostly of old, cold, dense rock that is more conducive to seismic waves.

On the West Coast, “the rocks are hotter, so they’re more active, they’ve experienced activity more recently, so they’re hotter, and they will attenuate or absorb some of the seismic energy as it moves through that rock.” Christopher CarchediA seismologist from the Carnegie Institution for Science in Washington, who was not involved in the research, said: Washington PostCarolyn Y. Johnson returned in April.

The East Coast is also less divided than the West Coast by fault lines that can interrupt seismic waves. According to the statement, existing fault lines date back about 200 million years, when Europe broke away from North America, and are sometimes still active.

Shortly after the New Jersey earthquake, Carchedi suggested that the unusual motion in the East Coast earthquakes could also be caused by the earthquake itself. Earth’s surface still readjusting Until the end of the last ice age, when the geology of the region was subjected to significantly greater weight under glaciers. Washington Post.

Either way, this event is a reminder that earthquakes are not limited to known seismic areas. Kim’s team also emphasizes that more research is needed to understand whether similar unusual earthquakes could target other large population centers in the future.

“If the (April) earthquake had been a little stronger or a little closer to New York, the impact would have been much greater,” Kim said in his statement. “We need to understand this phenomenon and its implications for ground motion prediction.”