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The Porter Ranch Gas Leak Is Officially the Largest in U.S. History

The L.A. gas spew was “equivalent to the annual energy sector methane emissions from medium-sized E.U. nations.”
Crews work on a relief well at the Aliso Canyon facility above the Porter Ranch area of Los Angeles.
Crews work on a relief well at the Aliso Canyon facility above the Porter Ranch area of Los Angeles.Dean Musgrove/Los Angeles Daily News via AP, Pool, File

Scientists had already been saying it, and now it’s a research-backed fact: The nearly four-month-long gas leak in the Los Angeles neighborhood of Porter Ranch was the largest in U.S. history.

In a paper published Thursday in Science, researchers report that the cracked well buried deep underground in the Southern California Gas Company’s San Aliso Canyon storage facility released some 97,100 tons of methane between October 23, when the leak was first detected, to February 18, when the well was sealed. That amount is the equivalent of about a quarter of the amount of methane emitted annually across the entire L.A. Basin.