Shortly before 7 p.m. on Monday, people in the Aroostook County town of Bridgewater reported feeling the ground shake. So did those due south in Monticello and north into Westfield and Presque Isle.
The U.S. Geological Survey quickly confirmed there had been a 2.3 magnitude earthquake. Not intense enough to cause damage, but enough to raise questions in northern Maine, where earthquakes are exceedingly rare.
But just how rare are they? The USGS and Maine Geological Survey have recorded at least 19 earthquakes in Aroostook County since 1990, according to records compiled in two separate databases.
We mapped each of them. Click on the circles to see details about each quake.
More than half of those tremors had a magnitude of 2.0 or less and were considered microquakes, which are generally not felt by people.
More than 170 earthquakes have been recorded in Maine since 1997, according to the Maine Geological Survey. The first one of 2026, with a magnitude of 1.3, occurred in Centerville.
Like the rest of the Northeast, Maine has no active faults, making it an area of relatively low seismic activity. But it still has some seismic action — like Monday’s earthquake in Bridgewater — because there are hundreds of old, dormant faults that crisscross the state and into eastern Canada.
“If you check the distribution of earthquakes, 99.9% of them occur along the plate boundaries, because these are active, mobile zones,” said Chunzeng Wang, an expert structural geologist and professor of earth and environmental studies at the University of Maine at Presque Isle.
“The old faults, normally we don’t have to worry. They are not active anymore, they are all sealed … but even if it’s sealed, you have to be careful, because it was broken before, it’s a weakness,” he said.
So as tectonic plates shift, stress can build along a fracture for thousands or millions of years. When that stress becomes greater than the strength of the rock it’s exerting force against, the rock breaks, the fault shifts, and that energy is released in waves.
Wang believes Monday’s earthquake occurred along the Hammond Fault, a fault he discovered and named that runs through Bridgewater and along the Canadian border, becoming the Rocky Brook-Millstream Fault in New Brunswick.
The epicenter was close to Bridgewater’s Packard Lake, which he said lines up with the westward angle of the Hammond Fault.
It was the first non-microquake recorded in Aroostook County since 2019.
The most memorable earthquake felt in northern Maine originated from Canada. The epicenter of a 5.8 magnitude quake in January 1982 that damaged homes and businesses in central Aroostook was located in the Northern Miramichi Highlands in New Brunswick, an area of greater seismic hazard.
The greatest seismic zone impacting Maine is just north of Quebec City along the St. Lawrence River, where 50 to 100 earthquakes are recorded annually.
