There's a new explanation for why the citizens of Clintonville, Wis., have been hearing booms this week:
"Thursday afternoon, geophysicists said it was likely a 'swarm of microquakes,' " as the Green Bay Press Gazette reports.
Indeed, the U.S. Geological Survey weighed in to say that it had detected a 1.5 magnitude temblor in the area around 12:15 a.m. (local time) on Tuesday.
According to the Press Gazette, it was just a fluke that the little quake was detected. It was measured by "traveling portable arrays that record seismic activity. ... Researchers don't have many of the devices in Wisconsin, and 'it was by fluke' that the portable detectors, which move around the country, were positioned near Clintonville recently, [City Administrator Lisa] Kuss said."
Scientists from USGS say you'd have to be within a few miles of such a quake to notice it. They suspect there have been others. Still, the newspaper adds, "several residents questioned the solution."
Milwaukee's WTMJ says "officials are going to continue investigating" to make sure there isn't some other explanation.