County officials have declared a state of emergency in the Porter Ranch neighborhood here, where more than 1,600 residents have been displaced by a massive natural-gas leak now entering its ninth week. Southern California Gas Co. says it may take until March to stop the methane flowing from an old oil field used to store natural gas. The utility, a unit of Sempra Energy SRE -1.61 % of San Diego, says it has made six unsuccessful efforts to stop the leak, which appears to be coming from a well rupture about 500 feet below the surface. The Federal Aviation Administration earlier this month instructed airplanes to avoid the area on the northwestern edge of Los Angeles, in the San Fernando Valley, effectively creating a no-fly zone around the 3,600-acre storage field, which has been in operation for about four decades. The agency’s action bans flights below 2000 feet […]