Updated 6:40 p.m.
A 3.8-magnitude earthquake was felt in parts of southern Vermont on Monday morning.
The earthquake originated off the coast of York, Maine, at 10:22 a.m., according to the U.S. Geological Survey.
Residents of Springfield and Brattleboro shared in community social media groups that they felt shaking for about 10-15 seconds. A magnitude of 3.8 is relatively mild, and Vermont Emergency Management said it received no reports of damage nor did the state dispatch centers see any surge in emergency calls.
Even though the quake occurred two states away, the rock that most of the Northeast sits on is particularly conducive to carrying seismic waves long distances, according to Will Amidon, a professor of earth sciences at Middlebury College.
“Because our rocks here (in the eastern U.S.) are so old and cold and dense, they actually propagate waves really well,” Amidon said. “Hard, dense rocks will pass a wave really efficiently while softer rocks or loose sediment can actually slow the wave down.”
While earthquakes are uncommon in the state, the Department of Environmental Conservation notes that between 2016 and 2020, there were 15 mild earthquakes with epicenters in Vermont — though residents reported feeling the effects of those in other states and Canada.
Although the region is not tectonically active anymore, it still gets mild, infrequent earthquakes because about 380 million years ago it was a hotbed for seismic activity, Amidon said.
“When this area was originally formed by continents colliding, this big fault zone, called the Norumbega Fault Zone, formed that was comparable to the San Andreas,” he said.
It left behind lots of tiny fault lines that are now areas of weakness where it is easier for rocks to slide past each other, even today. Amidon compared it to breaking an arm that’s been healed or a plate that’s been glued, but still most vulnerable where the original crack occurred.
Amidon stressed though that when this does happen, it should be infrequent and mild.
