Cause of the 4.8 magnitude earthquake in New Jersey that shook the East Coast



Many questions remain after a magnitude 4.8 earthquake struck New Jersey, Delaware and the surrounding region. What caused the earthquake? Was it to be expected? And how likely is it to happen again?

Like all earthquakes, Friday morning's tremor was caused by movements in the earth's crust. These movements most often occur along active fault lines, according to David Wunsch, director of the Delaware Geological Survey, but earthquakes outside these areas are not uncommon.

The quake on Friday morning had a magnitude of 4.8. But even if the quake was too small to cause major damage, Wunsch said it would still be one of the largest earthquakes in the region in decades.

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What caused a 4.8 magnitude earthquake in New Jersey?

The Earth's crust – the outermost shell of the planet – often adapts over time, Wunsch said. This settling and changing of the crust is the cause of earthquakes. This also causes quakes to occur unexpectedly in areas without active fault lines.

However, it was no coincidence that the earthquake was felt across the entire region on Friday morning. The quake's epicenter – about 3.1 miles northeast of Lebanon, New Jersey – is in the Piedmont region of the state. This is an area where rocks and crystals are very old, Wunsch said. They also transmit energy very efficiently, which may have led to the far-reaching effects.

There are also some failed rift valleys in northern New Jersey, Wunsch said. These are places where the continents attempted to separate hundreds of millions of years ago and are often associated with ancient faults. Wunsch said it was possible that activity along one of these fissures could have caused Friday's earthquake, but it would be “hard to say” until experts are able to analyze the data more thoroughly – a process that typically takes a few days lasts.

What's next after the New Jersey earthquake?

Due to the smaller magnitude of the earthquake, it is unlikely that anyone will be able to feel the aftershocks. Wunsch said people near the epicenter could see a “rattle,” but otherwise only sensors were able to detect the waves.

Wunsch added that there is no data to suggest that similar earthquakes are likely to occur in the region in the future.

“You have us in a pretty low-risk zone here,” Wunsch said.

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