Scientists at Idaho State University have mapped a previously unknown and active seismic fault in the northern Rockies capable of unleashing an earthquake with a magnitude as high as 7.5. Glenn Thackray, chairman of the university’s geosciences department, said the 40-mile-long fracture in the Earth’s crust at the base of the Sawtooth Mountains near the tiny mountain town of Stanley is cause for some concern. A 7.5 quake is considered a major earthquake, capable of widespread heavy damage. A tremor of this such size would be most felt at an epicenter near Stanley, which is home to about 100 year-round citizens. Moderate shaking would be expected from the community of Sun Valley to the the city of Boise. Scientists located the fault with a remote sensing technique that relies on laser-equipped airplanes. They were able to gather data about its history by analyzing sediment cores lifted from Redfish Lake, a mountain lake on the fault line. Researchers believe the fault triggered two earthquakes over the past 10,000 years, one some 7,000 years ago and another 4,000 years ago.