Communities across New England all the way down to Cape Cod and Martha's Vineyard felt a 3.8 magnitude earthquake Monday at 10:22 a.m. It was centered off the coast of York, Maine.
As of Monday evening, more than 38,000 people had reported feeling the earthquake, according to the United States Geological Survey, which tracks and studies earthquakes.
“This was a rather small magnitude earthquake,” USGS research geologist Alex Hatem said. “I know it might sound a little odd, because I know a lot of people felt it, but in terms of how big earthquakes can get, this is on the smaller side.”
Earthquake magnitude refers to the size of the earthquake at the source. Earthquake intensity, on the other hand, describes how the earthquake is felt by people in specific locations on a scale from 1 to 10.
Closest to the source, the earthquake was at intensity level 4.5. Sandwich and the Outer Cape experienced the earthquake at a level 3 intensity. The rest of Cape Cod, the South Coast, and parts of Martha's Vineyard experienced the earthquake at a level 2.5 intensity.
“Most people are reporting [that] they experienced the earthquake as observed by a table shaking or cabinets rattling,” Hatem said. “That sort of thing.”
An earthquake of this magnitude is unlikely to have caused structural damage, she said.
Earthquakes are rare in New England, Hatem said.
“Tectonically, this part of the world is at a passive margin, meaning it's not on an active plate boundary,” she explained. “Over long periods of time, those stresses really build and build, and eventually you have these moderate earthquakes.”
People on Cape Cod, the South Coast and Martha’s Vineyard were able to feel the earthquake from all the way in Maine because of the makeup of Earth’s crust in the northeast.
“The Earth's crust in New England, and really all across the east, is very cold and dense, and seismic waves can travel much further distances through this cold and dense crust,” Hatem said. “Unlike earthquakes that happen in California, which can be much larger, but they're felt over a much smaller area.”
There was another earthquake in Idaho just about an hour after the one in Maine, with a magnitude of 4.2. Hatem said it is not likely that the Maine earthquake triggered the Idaho one.
You can learn more about earthquakes at earthquake.usgs.gov.
