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Small earthquake rattles Montana

A small earthquake that rattled parts of the northern state Montana caused no damage but could be felt about 90 miles away.

The magnitude-3.7 earthquake that struck late Wednesday was an aftershock of a 5.6-magnitude quake that hit the same area of southwestern Montana in July 2005, said Tom Satterly, who manages the University of Montana-Western's environmental sciences department.

"It's the biggest (aftershock) we've seen in quite a while," Stickney said.

It was centered about 15 miles (25 kilometers) northeast of Dillon and could be felt as far as Helena, said Mike Stickney, director of earthquake studies for the Montana Bureau of Mines and Geology.

About 5,000 aftershocks have been recorded from the 2005 quake, which cracked walls and damaged bridges, Stickney said. The region averages about five aftershocks a day, most too small to be felt.