Did you also feel and hear it?
A minor M2.2 earthquake was felt like an explosion on August 24, 2017 in Casco Bay, Maine.

The 2.2 magnitude earthquake was reported around 11 a.m. about a half-mile offshore from Cape Elizabeth.
One resident reports the tremor didn’t feel very minor to him, feeling his entire house shaking and hearing a loud explosive noise.
Nearly a dozen minor earthquakes have been reported across Maine since 2015. The last significant earthquake in Maine happened on Oct. 16, 2012. It was felt more than 100 miles away in Boston.
The strongest earthquake recorded in Maine, a magnitude 5.1, happened in March 1904.