US | earthquake Wisconsin Town Figures Out Source of Mystery Booms 'Swarm of microquakes' apparently hit Clintonville By Matt Cantor Posted Mar 23, 2012 7:21 AM CDT Copied People turn out to get their questions answered at a meeting with city officials about the mysterious booming and rumbling in Clintonville, Wis., Wednesday, March 21, 2012. (AP Photo/Carrie Antlfinger) The mysterious booms heard in Clintonville, Wisconsin, had experts stumped—but there may be a simple explanation. "The mystery is solved. We have experienced an earthquake here in Clintonville," a city administrator explains. Geophysicists call it "swarm of microquakes," reports the Appleton Post-Crescent, and the administrator explains that the fact that Clintonville's soil and granite isn't like what's normally found under towns suffering earthquakes could be a contributing factor as well. Portable detectors picked up a magnitude 1.5 earthquake—which can only be felt within a five-mile radius—early Tuesday. The devices make their way around the country, and very few are in the state; it was a pure "fluke" that they were in the right place at the right time, adds the city official. But some geophysicists aren't 100% convinced. The data "is kind of going to throw everything into a tizzy," says one, who says the depth of the quakes need to be determined: A mile or two would be an earthquake; something shallower might not. Read These Next The Bezos-Sanchez wedding: guest list, cost, the dress, and more. Trumps ends trade talks with Canada. Actor Sam Rockwell gets residuals from movie he wasn't in. This is why your cat loves sleeping on its left side. Report an error