What Caused the Calif. Natural Gas Explosion?

A horrific explosion in San Bruno, Calif., yesterday initially prompted fears of an airplane crash. The source turned out to be a ruptured natural gas line, but what failure actually caused the deadly, Bruckheimer-like scene? 

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Ron Kendall, director of the Institute of Environmental and Human Health at Texas Tech University, says that he thinks the gas leak in San Bruno must have happened over time.

"When that explosion formed it blew 100 feet in the air. That suggests to me that it was more than a pipe breaking," he told me. "Once you’ve got a pocket of gas in a zone, once you get a source of ignition, it goes."

He wonders whether seismic activity could have caused cracks in the pipe.

Read the rest of the story at Discovery News