In this Oct. 2010 photo provided by the National Transportation Safety Board, an unidentified NTSB technician examines fractures on a ruptured section of pipeline at the NTSB training center in ... more 
In this Oct. 2010 photo provided by the National Transportation Safety Board, an unidentified NTSB technician examines fractures on a ruptured section of pipeline at the NTSB training center in Ashburn, VA. A gas pipeline that ruptured and caused a deadly explosion in a Northern California neighborhood showed no signs of corrosion and wasn't dented or leaking, federal accident investigators said Tuesday, Dec. 14, 2010. The NTSB has yet to determine what caused the transmission line to rupture on Sept. 9, 2010, killing eight people and destroying dozens of homes. less 
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Associated Press | Photo By NTSB
Thu, Dec 16, 2010 12:41 PM EST