A minor earthquake occurred this week near the eastern Wisconsin city where researchers have been investigating a series of unexplained booming sounds, federal geologists said Thursday.The U.S. Geological Survey said the 1.5-magnitude earthquake struck Tuesday just after midnight in Clintonville, a town of about 4,600 people about 40 miles west of Green Bay. Geophysicist Paul Caruso told The Associated Press that loud booming noises have been known to accompany earthquakes. It's possible the mysterious sounds that town officials have been investigating are linked to the quake, he said. Earthquakes can generate seismic energy that moves through rock at thousands of miles per hour, producing a sonic boom when the waves come to the surface, Caruso said. "To be honest, I'm skeptical that there'd be a sound report associated with such a small earthquake, but it's possible," he said. Those reservations didn't stop Clintonville City Administrator Lisa Kuss from...