PORTLAND, Maine — An earthquake in the mid-Atlantic state of New Jersey rattled the Northeast on Friday, and the effects of the quake were felt as far away as Maine.
The epicenter of the 4.8 magnitude earthquake was detected at a depth of nearly 3 miles below Whitehouse Station, New Jersey, which is about 50 miles outside New York City, according to U.S. Geological Survey data.
While the earthquake raised quite a bit of alarm, no major structural damage or injuries have been reported. More than a dozen aftershocks were detected in the hours after, including one that had a 4.0 magnitude Friday evening.
The USGS estimated that more than 42 million people felt the quake as it rattled the East Coast.
An expert with the Maine Geological Survey explained why people in Maine were able to feel the effects of the earthquake.
Senior geologist Henry Berry said the East Coast is part of an old, large tectonic plate that does not have as many fault lines as the tectonic plates on the West Coast, where earthquakes are a frequent occurrence.
Faults break up and interrupt the seismic waves, so they travel shorter distances. But along the East Coast, where there are fewer faults, waves can travel farther, even hundreds of miles away from the epicenter.
"It's solid and crystalline, and it rings like a bell, the crust," Berry explained. "It also depends on what the geology is right where you are, because seismic waves are amplified by the type of soil that you're on."
Berry said seismic waves travel right through solid bedrock and won't shake so much, but wet clay is going to vibrate and shake a lot.
Small magnitude earthquakes are relatively common in New England, though they are much less frequent and intense than those along the western U.S., as New England is far from the nearest active tectonic plate boundaries.
According to the USGS, earthquakes east of the Rockies can be felt over an area "as much as 10 times larger than a similar magnitude earthquake on the West Coast."
The most recent earthquake in New England to cause what the USGS considered "moderate damage" was a magnitude 5.6 quake that hit in central New Hampshire in 1940. The largest known earthquake detected as in recent times was a magnitude 6.5 that happened in 1638 somewhere in Vermont or New Hampshire, the USGS said in its tectonic summary of New England.
Berry said it's rare for New England to have big earthquakes measuring above 4.0 magnitude, but he shared safety tips for anyone who may need to know what to do in the event of an earthquake.
"It's pretty simple," he said. "Drop, cover, and hold on. That's it."
He also said Maine has building codes that are designed to handle the types of earthquakes that are common to the region.