ELLSWORTH, Maine — A small earthquake struck Blue Hill peninsula early Thursday morning, prompting a few calls to local law enforcement but causing no apparent damage.

The quake with a magnitude of 2.3 happened at 5:23 a.m., according to the Weston Observatory, a geophysical research lab at Boston College that monitors seismic activity. The observatory said the quake was located roughly 10 miles east-southeast of Searsport, or in the Brooksville area on Blue Hill peninsula.

The Hancock County Sheriff’s Office received four or five calls from people who heard a boom, felt their homes shake or noticed something else amiss, dispatchers said Thursday.

“A 2.3 [magnitude] is just at the boundary of being felt for a New England earthquake,” said

the Weston Observatory’s Alan Kafka, who is also director of Boston College’s Educational Seismology Project. “They tend to be very shallow.”

Small earthquakes are not unusual for this area of Maine or elsewhere in New England.

As he wrote in a paper titled, “Why Does the Earth Quake in New England?”, Kafka said quakes in New England and the Northeast are more challenging to decipher because, unlike California or Japan, the Northeast is not located near the boundary separating tectonic plates. But “intraplate earthquakes” are fairly common.

In October 2006, a 4.2 magnitude earthquake shook the ground beneath Bar Harbor and caused some large rocks to tumble onto the roadway in Acadia National Park.

In late April and early May of this year, meanwhile, monitors recorded a swarm of as many as 30 small quakes between Belfast and Bucksport. Most of those temblors measured less than 2.0 on the Richter scale, however.

Kafka said such earthquake swarms still fascinate him, even though he watches seismic activity all the time. That swarm appears to have ended around May 4. But most earthquakes have aftershocks, so Kafka said it was not out of the question that Mainers could experience additional shaking.

Although Thursday’s quake was minor, reverberations were felt on the western side of Penobscot Bay. A Northport woman who was up and getting ready to garden at about 5 a.m. said she suddenly felt a “gentle rumble” as the ground shook.

“My first instinct was that it was an earthquake,” said Judy Berk, who lives on Beech Hill. “Then I said to myself — maybe it was thunder. Maybe it was a heavy truck.”

It all happened too fast and was too small to be scary, she said, and when she saw early news reports that there had been an earthquake, it all added up.

“When I read about it, I thought, ‘Oh, that makes perfect sense,’” Berk said.

BDN writer Abigail Curtis contributed to this report.