Thursday, June 16, 2011

New Quake Fault Found in California

The Polaris Fault
Credit: U.S. Geological Survey (BSSA/USGS/USACE)

A new earthquake-producing fault has been discovered in California. The Polaris line, at only 22 miles long, is a dwarf compared to the San Andreas Fault, which stretches 800 miles and has triggered some of the world�s biggest tremors.

Polaris is said to be powerful enough to cause an earthquake measuring 6.9 on the Richter Scale and flood a valley by smashing a dam.

The Polaris Fault was discovered using laser imaging technology known as LiDAR, which was used as part of the U.S. Army Corps of Engineers� evaluation of the dam. LiDAR emits laser pulses down toward the ground from an airplane � even through dense vegetation � to get high-resolution topology maps. Once researchers stripped off the heavy pine tree layer from the maps, they found evidence of the fault sitting just 200 meters from the dam.

Scientists with the U.S. Army Corps of Engineers were inspecting the Martis Creek Dam, which sits just outside Truckee, California and about 35 miles upstream from Reno. It is one of 10 dams in the United States that has �urgent and compelling� safety concerns, according to the Corps, which owns the dam. Data from the most recent evaluation revealed that, not only does the dam have significant leakage, it also lies in close proximity to not two, but three fault zones. If it broke, the Martis Creek Dam has the potential to deluge the homes of 16,000 people in nearby Truckee and flood waters could travel 35 miles to Reno, Nevada, where 220,000 people live.

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