Although earthquakes are fairly common in the southwestern part of Indiana and occasionally happen along the edge of Lake Michigan, earth scientists say there has never been an earthquake confirmed in north central Indiana.

"Unprecedented," said Walter Gray, an official with the Indiana Geological Survey, a research group at Indiana University. "There is no historical evidence of quakes in that area. We have no events that have been recorded."

Seismologist Michael Hamburger, an IU professor of geological sciences, called north central Indiana "a really quiet corner of the seismic world."

"This is an interesting little peculiar earthquake that happened in a strange place," Hamburger said of Thursday's quake. "It is a reminder that earthquakes can happen almost anywhere in the central U.S."

The southern half of Indiana, which includes the Wabash Valley Fault System, is more prone to quakes. There was a 3.8 magnitude quake as close as Shelbyville in 2004. The last major quake centered in Indiana was a 4.6 magnitude earthquake near Evansville in June 2002, according to the U.S. Geological Survey.

What is the Sharpsville Fault?

Indiana Geological Survey Director John Steinmetz thinks the Sharpsville Fault, which is named after the Indiana city, and runs between Tipton and Howard counties, may have played a role in Thursday's quake. If so, it would be a first for the Sharpsville Fault. There is no record of it ever being related to an earthquake. The fault is 13 miles long, relatively short for a fault, Steinmetz said, and it was last active geologically about 360 million years ago.