4.8 magnitude earthquake in New Jersey felt in Delaware, along East Coast. What we know

The shaking began just after 10:23 a.m. Friday.

Some felt their houses move and thought it was construction workers. Others thought it was simply heavy traffic rumbling by.

But as Delaware residents and others up and down the East Coast took to social media to question the shaking, it quickly became clear − and was soon confirmed by the U.S. Geological Survey − that an earthquake had hit the area.

The 4.8 magnitude quake occurred about 4.3 miles north of Whitehouse Station, New Jersey, in the northern part of the state. Shaking lasted less than 30 seconds.

According to the moment magnitude scale, which is used to measure earthquake magnitude and has replaced the previously used and well-known Richter scale, it was considered a "light" earthquake.

Still, the geological survey posted on X that it was "notable" and marked the most significant one in New Jersey since 1884.

NJ earthquake: 4.8 magnitude earthquake struck New Jersey Friday morning. What caused it and what's next

Residents in Washington, D.C., Virginia, Maryland, Pennsylvania, New York, Connecticut, Rhode Island, Massachusetts and Maine all reported feeling the earthquake, according to the U.S. Geological Survey's website.

"I'm still shaken about it," one person posted on X.

How are earthquakes measured?

Scientists measure earthquakes on a scale of 1 to 10, with 10 being the strongest and 1 being the weakest. The weakest ones occur daily, while an earthquake of magnitude 10 is considered a "mega quake" − though that would likely be a world-ending catastrophe.

No earthquake has ever been registered on the scale above magnitude 9.5. That occurred in 1960 in Chile on a nearly 1,000-mile-long fault. Faults are cracks in the earth where earthquakes are more prone to occur.

Earthquake magnitudes are determined by seismometers, which record the vibrations that travel through the earth.

RELATED: Delaware hit by at least 59 earthquakes since 1871

They are very sensitive instruments and greatly magnify ground motions, meaning they can detect strong earthquakes anywhere in the world, the U.S. Geological Survey said. They record motion as a function of time.

Because each whole number increase in magnitude represents a tenfold increase in measured amplitude, a 5.3 earthquake, for example, is considered "moderate," while 6.3 is considered "strong."

Scientists don't believe there is a fault long enough to generate a magnitude 10 earthquake. If it did, it would extend around most of the world.

Are earthquakes common in this area?

The U.S. Geological Survey posted on X Friday morning that earthquakes are "uncommon but not unheard of along the Atlantic Coast."

This is a zone that one study called a "passive-aggressive margin," the post said, because "there's no active plate boundary between the Atlantic & N. American plates, but there are stresses."

A 2.1 magnitude earthquake with an epicenter in Clarksville, Maryland, occurred in August 2021, with Delaware residents reporting they felt shaking from that incident. Earthquakes of that magnitude are considered "minor."

And in November 2017, a magnitude 4.1 earthquake occurred near Dover. At the time, it was the largest one since 1871, when one of the same magnitude struck the Wilmington area.

According to the Delaware Geological Survey, operated out of the University of Delaware, the 2017 earthquake was Delaware's most recent.

Earthquake devastation in Taiwan this week

Friday's quake in New Jersey comes days after a 7-plus magnitude earthquake hit Taiwan, killing at least 10 people and injuring more than 1,000.

It was measured as magnitude 7.2 by Taiwanese officials and 7.4 by the U.S. Geological Survey. It struck near the east coast city of Hualien at about 8 a.m. local time, USA Today reported.

Hualien is a popular tourist destination 100 miles south of Taipei, where buildings swayed and some damage was reported. A series of aftershocks followed, reaching up to 6.4 magnitude.

The quake set off a tsunami warning for southern Japan and the Philippines that was later lifted.

TAIWAN EARTHQUAKE: Rescue effort in massive Taiwan earthquake may take a 'Herculean effort': Updates

It's not yet clear if anyone was hurt in New Jersey's earthquake on Friday. The U.S. Geological Survey does predict there will be at least one aftershock, which is a smaller earthquake or series of earthquakes that follow the largest shock of an earthquake sequence.

DelDOT has not received 'any reports of issues'

The Delaware Department of Transportation said Friday morning it would be inspecting about 30 bridges in New Castle and Kent counties with tall bearings or that are movable "to confirm there is not any misalignment as a result of the earthquake," spokesman C.R. McLeod said.

While the agency has not received "any reports of issues or damage" to infrastructure, the department is checking these drawbridges or taller bridges "out of an abundance of caution."

The Delaware Memorial Bridge won't be looked at by DelDOT, as it's not owned by the agency. The Delaware River and Bay Authority, however, said it had inspection teams on site that would be looking at bridge components.

DRBA handles operations for that bridge. The inspection is "precautionary," said agency spokesperson Jim Salmon.

Gov. John Carney posted on X late Friday morning that the Delaware Emergency Management Agency is "monitoring the situation" in Delaware. New Jersey Gov. Phil Murphy said that state has activated its emergency operations center.

Got a story tip or idea? Send to Isabel Hughes at ihughes@delawareonline.com. For all things breaking news, follow her on X at @izzihughes_

This article originally appeared on Delaware News Journal: 4.8 magnitude NJ earthquake felt in Delaware, along the East Coast