A 3.3-magnitude earthquake that struck 13 miles southeast of Battle Creek today has scientists scratching their heads. Today’s temblor was about 20 miles from the location of a magnitude-4.2 quake that occurred 5 miles south of Galesburg on May 2 — the strongest earthquake recorded in Michigan in more than 67 years.

The two quakes are far enough apart that today’s is likely not an aftershock of the previous quake and is apparently not on the same fault line, said Harley Benz, a seismologist with U.S. Geological Survey (USGS) in Colorado. “After the May event, I suspected we wouldn’t see another event, so I was a bit surprised by this one,” he said. “What more surprised me is that they weren’t in the same locations.” FULL REPORT