The Aliso Canyon gas leak (also called Porter Ranch gas leak[1] and Porter Ranch gas blowout[2]) was a massive natural gas leak that was discovered by SoCalGas employees on October 23, 2015.[3] Gas was escaping from a well within the Aliso Canyon's underground storage facility in the Santa Susana Mountains near Porter Ranch, Los Angeles.[4] . . . On January 6, 2016, Governor Jerry Brown issued a state of emergency.[5] The Aliso gas leak's carbon footprint is said to be larger than the Deepwater Horizon leak in the Gulf of Mexico.[6] On February 11, 2016, the gas company reported that it had the leak under control.[7] On February 18, 2016, state officials announced that the leak was permanently plugged.
An estimated 97,100 tonnes (95,600 long tons; 107,000 short tons) (0.000097 Gt) of methane and 7,300 tonnes (7,200 long tons; 8,000 short tons) of ethane were released into the atmosphere,[8] The initial effect of the release increased the estimated 5.3 Gt of methane in the Earth's atmosphere by about 0.002%, diminishing to half that in 6–8 years.
It was widely reported to have been the worst single natural gas leak in U.S. history in terms of its environmental impact.[9][10][11] By comparison, the entire rest of the South Coast Air Basin combined emits approximately 413,000 tonnes of methane and 23,000 tonnes of ethane annually. . . .[12]
Local residents have reported headaches, nausea, and severe nosebleeds.[4] About 50 children per day saw school nurses for severe nosebleeds.[29] There have been more than usual eye, ear and throat infections.[21] By December 25, 2015, more than 2,200 families from the Porter Ranch neighborhood had been temporarily relocated, and more than 2,500 households were still being processed.[34] As of January 7, 2016, 2,824 households or about 11,296 people had been temporarily relocated by SoCal Gas,[28] while more than 6,500 families have filed for help.[37] Two schools were relocated in January. . . .[14]