A thank-you sign is posted in front of a saved home about a block from destroyed homes in San Bruno, Calif., Tuesday, Sept. 14, 2010, where a pipeline exploded on Thursday. The tragic explosion of a gas pipeline has shed light on a problem usually kept underground: Communities have expanded over pipes built decades earlier when no one lived there. Utilities have been under pressure for years to better inspect and replace aging gas pipes, many of them laid years before sprawling communities were erected around them, that now are at risk of leaking or erupting. (AP Photo/Paul Sakuma)