An earthquake struck New Jersey and shook buildings in surrounding states this morning – leaving an estimated 42 million people feeling the seismic impacts of the phenomenon, according to the U.S. Geological Survey.

"Our region just experienced an earthquake with a preliminary magnitude of 4.7, with an epicenter near Readington in Hunterdon County," New Jersey Gov. Phil Murphy said in a statement. 

"We have activated our State Emergency Operations Center. Please do not call 911 unless you have an actual emergency." 

New York City Mayor Eric Adams also spoke out during a press conference following the quake.

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"At approximately 10:23 a.m., New York City felt the impact of a 4.8 magnitude earthquake," Adams said. 

"The epicenter was in Lebanon, New Jersey, about 50 miles from New York City. Our first responders are working to make sure New Yorkers are safe, and at this point, we do not have any reports of major impacts or injuries."

East Coast residents who aren’t typically prepared for an earthquake might be wondering how to stay safe in the event that the U.S. experiences another large tremor, or an aftershock.

Adams encouraged New York residents to check on their loved ones, and to follow safety tips in the event of an aftershock, which is a smaller earthquake that follows a larger earthquake.

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"So far no major life safety issues [are] reported, no reported infrastructure issues — but we will continue our inspections of critical infrastructure," Adams said.

New York Gov. Kathy Hochul said her team felt the earthquake in the state capital of Albany.

"This is one of the largest earthquakes on the East Coast to occur in the last century. So I immediately directed my emergency management team the second we received word of this to start doing damage assessments," Hochul said.

Hochul, who also mentioned the quake that hit New York in 2011, posted on X that she and her team are "monitoring and preparing for the possibility of aftershocks."

Theresa Sawi, a seismologist of Columbia University's Lamont-Doherty Earth Observatory, told FOX 5 NY that a magnitude-5 earthquake hitting California is "potentially less devastating" than a magnitude-5 earthquake hitting the East Coast.

"And that's because the geology in the East Coast – the ground is colder, older and more brittle," Sawi told the station.

"So when seismic waves hit, it rings through the ground like a bell. And those seismic waves can be felt at a greater distance on the East Coast."

Fox News Digital reached out to Sawi for comment.

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The American Red Cross posted safety tips along with a link to X after the earthquake rattled New Jersey, New York, parts of Pennsylvania, Connecticut and more states.

The nonprofit advises people to "expect and prepare for aftershocks, watch out for fires, which are common after earthquakes and to take photos of damage for your insurance company." 

The American Red Cross also said to make sure to protect yourself from falling debris, according to its website.

It shared this additional information.

To prevent injuries, look out for things that might fall in the event of an earthquake. 

"Consider things such as televisions, shelves, mirrors, pictures, water heaters, refrigerators, and bookcases. Secure these items so they don't injure you during an earthquake. Straps, hooks, latches, and other safety devices are widely available," the American Red Cross' site said.

The Centers for Disease Control and Prevention (CDC) advises that "if you are inside, stay inside."

"DO NOT run outside or to other rooms during an earthquake," the CDC's website states. "You are less likely to be injured if you stay where you are."

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The CDC also advised people not to stand in a doorway. 

"Doorways do not protect you from the most likely source of injury − falling or flying objects," agency officials wrote.

For more tips, visit the American Red Cross’ webpage titled, "Earthquake Safety" on redcross.org, and/or the CDC’s online article addressing how to "Stay Safe During an Earthquake."

Fox News Digital's Chris Pandolfo contributed to this report.

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