While it was one of the strongest quakes on record for the region, many others go unnoticed. The earliest records of earthquakes in Pennsylvania date back to colonial times.

Within Pennsylvania sits the Reading-Lancaster seismic zone, which is responsible for many of those tremors.

The map below shows the location of past earthquakes reported around Pennsylvania and neighboring states. Click on a marker for more details, including the magnitude, of each quake.

Source: U.S. Geological Survey

How common are earthquakes in eastern PA and why was the New Jersey earthquake felt so far away? 

USGS research Paul Earle told reporters during a news conference Friday afternoon that there have been similar earthquakes in that area over the past 100 years or so. He described the latest as normal.

It’s the strongest earthquake to be felt in our region since Aug. 23, 2011, when a magnitude 5.8 tremor in Virginia was felt from Canada to Georgia and even left cracks in the Washington monument. That earthquake was the strongest on the East Coast since World War II.

But there have been a number of smaller quakes before and after that one, most of which go unnoticed.

“There is a seismic zone in Pennsylvania, the Reading-Lancaster seismic zone,” according to Anne Meltzer, a professor of seismology at Lehigh University. “It tends to have more magnitude 3 [quakes]. People in the Lehigh Valley sometimes feel those.”

Here is a look back at some of the more notable earthquakes over the years, according to The Morning Call archives:

The earliest records of earthquakes in Pennsylvania date back to colonial times. USGS records show Pennsylvanians may have felt an earthquake along the St. Lawrence River in 1663, another at Newbury, Mass., in 1727, and another in New York City on Dec. 18, 1737.

Two severe earthquakes struck Philadelphia in 1800, one March 17 and one November 29. And earthquakes on Nov. 11 and 14, 1840, were reported to have created unusually large swells on the Delaware River.

PA earthquake history: See historical map of earthquakes recorded around region

There were reports of an earthquake shaking dishes off tables in Allentown on May 31, 1884, and a few chimneys in Allentown were toppled during an earthquake on May 31, 1908.

Plaster walls, dishes, bottles and furniture were tossed around in an earthquake in Sinking Spring, just outside Reading on Jan. 7, 1954.

A moderate earthquake was centered in the Lehigh Valley Sept. 14, 1961. The only reported damage involved bricks from a chimney in Allentown, but according to reports, police and newspaper switchboards were swamped with calls from Bethlehem, Catasauqua, Hellertown and Weaverville.

In western Pennsylvania, a 5.2 magnitude quake rocked the Greenville-Jamestown area and was felt throughout the state, as well as in parts of Ohio, Indiana, Ontario, Michigan, New Jersey and West Virginia, according to the U.S. Geological Survey.

Other minor tremors have struck Philadelphia in 1961, Cornwall in 1964, a New Jersey earthquake could be felt in Darby in 1968 and in 1972 slight damage was reported in New Holland. In 2015, a magnitude 2.5 earthquake struck Bernardsville in central New Jersey and was felt in Pennsylvania.

Why East Coast earthquakes are felt so far away

Earthquakes on the East Coast are felt more and over a larger area than ones on the West Coast. Earle said the rock on the East Coast is harder and seismic waves travel further.

“You’re going to have a lot more people feeling this earthquake than you would with a similar sized earthquake in California,” he said.

Meltzer said the impact of quakes differs based on their depth. The energy from a deep earthquake is weakened as it passes through layers of rock and sediment, whereas shallow quakes retain their energy. That’s why they tend to be more destructive.

Typical of quakes in this region, Friday’s was fairly shallow — about 4.7 kilometers deep — but its relatively low magnitude kept it from doing much damage.

The USGS maintains a “Tell Us” feature on its website inviting users to describe the intensity of quakes in their area. Those descriptions can vary widely, Meltzer said.

“Sometimes there are site conditions that can amplify the motions,” she said.

“It actually can be quite different locally depending on whether you’re close to bedrock, which is really firm, or sedimentary rock, which is less so.”

Larry Malinconio, associate professor of geology at Lafayette College, said he was in his home in Easton’s College Hill section when he felt the quake.

“This was pretty substantial in the sense you could feel the side-to-side motion,” Malinconico said.

Malinconico said about 1 million earthquakes occur worldwide per year with most going undetected by residents.

“We don’t live in California, so we don’t have frequent earthquakes,” he said, “but there are old fracture systems in the northeastern part of North America, and occasionally they slip.”

How to check for earthquake damage to your home

While LVHN is a familiar name to Lehigh Valley residents, Jefferson may not be. But the Philadelphia-based health care system has been growing through mergers and acquisitions in recent years.

Here’s what you need to know about Jefferson Health.

How big is Jefferson Health?

Jefferson has a network of 18 hospitals and physician practices in Bucks, Montgomery and Philadelphia counties in Pennsylvania, and Camden and Gloucester counties in New Jersey.

Jefferson has more than 42,000 employees, making it the second-largest employer in Philadelphia and the largest health system in the region by total licensed beds.

Jefferson is also home to Health Partners Plans, an HMO with nearly 400,000 members that provides a range of health coverage, including Medicare, Medicaid and Children’s Health Insurance Program.

Jefferson’s history

Jefferson was founded in 1825 as the Infirmary of the Jefferson Medical College, later known as the Hospital of Jefferson Medical College. In 1996, it merged with Methodist Hospital in South Philadelphia.

Jefferson began a major expansion into the Philadelphia suburbs in 2015 when it acquired Abington Health in Montgomery County. The following year it acquired Aria Health, which had hospitals in Philadelphia and Bucks County. In 2017, Kennedy Health, a southern New Jersey-based health care system, joined Jefferson.

In 2021, Einstein Healthcare Network became part of Jefferson.

What is Jefferson known for?

In addition to its hospitals, Jefferson Health is home to the medical college Thomas Jefferson University.

It’s also home to the Sidney Kimmel Cancer Center, one of only 70 National Cancer Institute-designated cancer centers in the country. Its flagship hospital is Thomas Jefferson University Hospital in Philadelphia.

Thomas Jefferson University Hospitals ranked second in the Philadelphia region and third in the state in U.S. News & World Report’s annual “Best Hospitals” rankings.

The northbound lanes of Interstate 476 reopened around 10:30 p.m. Saturday, and the southbound lanes reopened around 6 p.m. The highway had been closed between Mid-County Exit 20 and Lansdale Exit 31.

The crash occurred just before 10:30 a.m. in the northbound lanes of Interstate 476  around mile marker 26 in Worcester Township.

A vehicle with a flat tire came to a stop in the right lane of the highway and another vehicle behind it stopped and the driver activated hazard lights. The truck was unable to stop and struck both vehicles, and all three became engulfed in flames, police said.

The truck driver and the driver of the first vehicle struck were killed, while the other driver sustained minor injuries, state police spokesperson Myles Snyder told The Philadelphia Inquirer.

Photos and video shared to social media, including one by passing driver Hector Lucena, showed large flames engulfing a tanker truck with the words “Jet Fuel” on it, off to the side of the northbound lanes. The tanker appeared to have crashed into a car.

Just before the tanker, the highway was covered with debris.

As of 2 p.m., the fire appeared to have been extinguished, aerial video taken by CBS Philadelphia showed.

Turnpike employees worked throughout the morning and afternoon to direct traffic stuck on the highway to the emergency access gates. Eventually crews removed a section of the concrete median, allowing vehicles stuck on I-476 north to turn around.

At around 3 p.m., the Turnpike in a post on X, formerly known as Twitter, said that all vehicles in the traffic queue had been U-turned

All trapped queue has been U-Turned. If you are still in the closed section of I-476 North / South between Mid-County Exit #20 & Lansdale Exit # 31 – Call *11 (Star 11) and tell the dispatcher your milepost location so we can get you U-Turned. pic.twitter.com/NRt7LOnYhz

— PA Turnpike Alerts (@PATurnpikeAlert) October 21, 2023

Earlier, Turnpike officials warned that clearing the highway of traffic would be a “slow process.” Northbound traffic could not proceed — and thus had to be turned around — due to damage to the highway and a bridge that “needs inspected to make sure it is safe for vehicle travel.”

Due to the nature of the hazmat incident, authorities had earlier requested that drivers who were stuck on the highway near the fire remain in their vehicles.

Crews are u-turning vehicles to gate at mile 23. This is a slow process. Unfortunately traffic can not be released north due to fire keeps reigniting & also damage to roadway/bridge that needs inspected to make sure it is safe for vehicle travel. Crews are now en-route with…

— PA Turnpike Alerts (@PATurnpikeAlert) October 21, 2023

CBS Philadelphia reported that residents were briefly evacuated from homes on two nearby roads.

The Associated Press contributed to this report.