Rare Maine earthquake shakes New England, rattling states from Mass. to R.I.

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A rare 3.8-magnitude earthquake off the coast of Maine rocked New England on Monday morning, shaking homes and buildings as far away as coastal Rhode Island and Connecticut and Albany, N.Y., making it the strongest quake since last April’s more forceful tremor in northern New Jersey.

The United States Geological Survey said the quake struck at 10:22 a.m. and was centered about 6 miles southeast of York Harbor, with a depth of 8 miles. The USGS initially estimated the earthquake had a magnitude of 4.1 before lowering it to 3.9 and then to 3.8.

An event like this, closer to a 4.0 magnitude “happens about one in five years. Is it rare? Possibly,” said John Ebel, a senior research scientist at the Weston Observatory at Boston College. “When you get to or above a 5.0 magnitude, which happens about every 100 years, that’s where damage occurs.”

The last 3.8-magnitude quake to shake Maine was 25 years ago on Feb. 26, 1999 near China, Maine, northeast of Augusta.

Sophie Coulson, assistant professor in Earth science at the University of New Hampshire, was preparing for class when the earthquake hit near what Coulson said is called the Portsmouth fault.

“The US East Coast is not on an active tectonic boundary, so it’s pretty infrequent that we see earthquakes happening,” she said.

Frightened callers

New Hampshire 911 said it did not receive any emergency calls about damage or injuries as of 10:45 a.m. Anyone concerned about possible structure damage to their home or business were being told to contact their local fire department.

Some callers to the York, Maine Police Department questioned whether an explosion had rocked the coastal town, said Sergeant Brian McNeice.

“There were multiple calls in town and to our dispatch centers all over Southern Maine,” he said in a telephone interview. “I think it was the rumbling, like a truck. I think it was the rumbling plus the shaking and people assumed there was an explosion.”

A camera operated by the Stage Neck Inn in York Harbor Beach, Maine shook as seen in this video:

McNeice said his department sent officers around town after the quake — which he estimated lasted 5 to 7 seconds — ended. “So we checked the area, and luckily, no damage, no houses damaged, nothing out of sorts at this point. Nothing’s been reported since it finished,’’ he said.

How does this tremor compare to other quakes?

This morning’s quake was the largest earthquake to hit the Northeast since an earthquake shook northern New Jersey on April 5, 2024, with 4.8 magnitude, according to the USGS.

“Today’s quake was 10 times smaller in amplitude and 30 times smaller in energy than last April’s earthquake centered in New Jersey,” said Leslie Sonder, an associate professor of Earth sciences at Dartmouth College.

Other Maine earthquake facts:

• Although the last 3.8 quake struck in 1999, the last moderate-type of earthquake to hit Maine was a 3.3-magnitude quake on Jan. 14, 2023 in Dedham, Maine.

• The largest earthquake ever to hit Maine was over a century ago — at a magnitude 5.7 in 1904 between Bar Harbor and Passamaquoddy Bay.

• And today’s tremor is the 18th strongest earthquake to occur in or off the coast of Maine on record.

McNeice said Monday’s quake was the first he had ever experienced. ”It was nerve-wracking. It doesn’t happen around here, so that’s a new one. It was definitely a first. It was kind of confusing at first, but we kind of realized pretty quickly what was going on.”

Seabrook Station, a nuclear power plant operated by NextEra Energy Resources in Seabrook, N.H., sits about 26 miles south-southwest from York Harbor.

A spokesperson said the New Hampshire Department of Safety Division of Homeland Security and Emergency Management has been in contact with Seabrook Station and there are no concerns related to the power plant at this time. The spokesperson noted that people who live, work, or vacation within a 10-mile emergency planning zone around Seabrook Station should familiarize themselves with the zone’s emergency plans and procedures, which are available online.

Immediately after the quake, the US National Tsunami Warning Center said a tsunami was not expected to hit the area.

What about aftershocks?

Tasha Dunn, a professor of geology at Colby College, said this quake was probably too weak of an event to have any secondary earthquakes or aftershocks, but they’re not impossible.

Keep in mind, she said, that we do “experience earthquakes in the Northeast on a fairly regular basis that are really, really teeny tiny. So it might honestly be difficult to distinguish aftershocks of this earthquake from other earthquakes that are just occurring on a regular basis.”

Geologists and seismologists will study the aftershocks to ultimately understand the reason behind this particular earthquake.

How earthquakes occur

“Earthquakes happen when you have a release of energy, a very sudden release of energy from inside the earth,” said Dunn. “Usually those occur on what we call faults, which is kind of a crack... in a rock, a rock moves over time, it gets stuck, and so when it’s able to finally slide past another rock and release that energy, you get an earthquake.”

Coulson said this earthquake was likely caused by pressure from an active tectonic plate boundary in the middle of the Atlantic Ocean, where two plates are splitting apart and creating volcanos in between them. That means there’s a portion of the western Atlantic Ocean pushing toward the US East Coast, according to Coulson.

She said it appears the earthquake struck along a pre-existing fault, an area where the rock is already weakened because it was once a fault line when the Appalachian Mountains were first being formed. As Coulson and other experts pointed out, the quake most likely occurred along the Portsmouth fault, also known as the Norumbega Fault Zone, a major “strike-slip fault” area located in the Gulf of Maine.

The type of fault off the coast of Maine is a strike-slip fault where two plates slide past each other.Boston Globe

The Norumbega Fault Zone (designated as NFS above) runs along the coast of Maine.ResearchGate

And as all earthquakes do, it traveled in seismic waves, vibrations that move through the Earth. “They start at the source of the earthquake and then move away from the earthquake if you can imagine like throwing a rock into a pond,” according to Dunn.

“We don’t think about this very much as regular people, but the Earth is always active and is always moving,” said Dunn. “And like right now, the surface of the Earth in New England is actually still rebounding from the last Ice Age.”

Reaction was quick and rattled some nerves

People quickly posted on social media that they felt a brief rumble as far south as southern Rhode Island.

“Did anyone else in the Boston area feel the ground shake pretty hard under their feet? Our house just shook in a way I’ve never felt before,” Carole Hooven from the Boston area posted on X. “Wondering if it could’ve been an earthquake.”

Pete Bouchard, chief meteorologist for NBC Boston, thought the sudden rumble was a “massive sonic boom.”

New Hampshire emergency management officials said residents and visitors should be prepared for all types of hazards, including earthquakes.

“Include all hazards when you are creating a family emergency plan,” said HSEM Director Robert Buxton. “You should also hold regular drills to practice what to do during an earthquake. It’s the best way to keep you and your family safe.”

During an earthquake, officials advised that if you are inside, you should “drop, cover and hold on.” If you are outside, you should move away from buildings and other items that can topple over.

This quake “reminds us that earthquakes are unusual but not unheard of along the Atlantic Seaboard,” the USGS said on social media.

Amanda Gokee, Niki Griswold, Amanda Kaufman, Jenna Perlman and Marianne Mizera of the Globe staff contributed to this report. Globe correspondent Chris Gloninger also contributed.