A massive natural gas leak in Aliso Canyon, California, about 25 miles north of Los Angeles, has been spewing about 62 million standard cubic feet of methane per day into the air since a well casing mysteriously suffered damage on Oct. 23 of this year.

The leak is unlikely to be squelched for another three to four months, according to SoCalGas, as crews have to drill about 8,500 feet underground to intersect with the base of the leaking pipe.

Already, more than 1,000 people in Porter Ranch and Northridge, California have temporarily relocated due to health complaints related to the fumes from the leak. In addition, the Los Angeles Unified School District's Board of Education decided on Dec. 17 to temporarily relocate two schools for the rest of the 2015-16 school year.

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The Aliso Canyon leak demonstrates a potential blind spot in the nascent regulatory system for overseeing the country's growing natural gas infrastructure. Companies are being pushed to contain leaks in their natural gas pipelines and at facilities that burn natural gas, but underground storage areas, of which there are more than 300 nationwide, aren't subjected to specific standards that might have prevented this leak.

Visible image and infrared image revealing the natural gas leak from Aliso Canyon, California. Image: EDF

California has been monitoring the air quality in the Porter Ranch community, which is closest to the leak and where many people have complained about health issues. They have found that, so far, the level of pollutants in the air, including benzene, which can be extremely hazardous when present in particularly high levels, has remained below the threshold where they would be considered dangerous.

However, natural gas odorants can cause adverse physical symptoms, including nausea and headaches, despite the lack of long-term health risk. A spokesman for SoCalGas told Mashable that the company "recognizes the impact this incident is having on the environment," but said it's unsure exactly how much gas has escaped so far.

According to the state, the source of the leak appears to be a damaged well casing about 500 feet underground. It's unclear what caused the damage, according to the California Division of Oil, Gas, and Geothermal Resources. The well passed an annual mechanical integrity test last year.

However, seven routine attempts to kill the well (that is, stop the flow of gas through that well casing) failed, so workers are now drilling a so-called "relief" well to intersect the leaking well at a depth of 8,500 feet below the source of the leak. This is because heavy mud and brine has to be delivered near the origin of the gas in order to cut off the flow of gas toward the surface.

According to the Division of Oil, Gas and Geothermal Resources, the drilling has to be done from at least 1,000 feet away from the well, due to the risk of igniting the escaping gas. The relief well drilling began on Dec. 4 and is now at 3,800 feet of the 8,500 feet they are drilling down to, per an email from SoCalGas.

"So the contractor must complete several thousands of feet of drilling — both from a distance at the surface and underground — and hit the casing of another well, a relatively small target," the division said in a list of bullet points sent to Mashable via email.

Equivalent to "8 or 9 coal plants"

The climate implications of this particular leak are significant, especially since the leak is in California, which has some of the most stringent greenhouse gas emissions reduction plans in the world.

The main component of natural gas is methane, which can have up to 80 times the warming power of carbon dioxide for the first 20 years after it is released, before it begins to be removed from the atmosphere through natural processes.

Screenshot from aerial footage of the Aliso Canyon natural gas leak. Video: YouTube, Screenshot; YouTube, Environmental Defense Fund

According to Dave Clegern, the spokesman for California's Air Resources Board, which regulates the state's greenhouse gas emissions sources, it's unclear exactly how much methane has escaped into the atmosphere so far, but it appears that the leak rate is slowing down.

"This is a major leak, but beyond that we really won’t be able to reach any conclusions until after the leak is sealed," he told Mashable. The leak has increased the state's greenhouse gas emissions from methane by 25%, but methane only constitutes about 9% of total greenhouse gas emissions in California. Other greenhouse gases emitted in California include carbon dioxide and nitrogen oxide, for example.

The environmental group Environmental Defense Fund, which emphasizes the need to eliminate methane leaks in order to reduce the climate impact of natural gas, says that the Aliso Canyon leak has amounted to about 62 million standard cubic feet of methane per day.

"That’s the same short-term greenhouse gas impact as the emissions from 7 million cars," the group says on its website.

Timothy O'Connor, who directs EDF's oil and gas program in California, said the Aliso Canyon leak is of a size and scope that is “unprecedented for California.”

It's about equal to the emissions from eight or nine coal-fired power plants, he said in an interview.

As utilities have increasingly turned to natural gas as the country's main source of fuel for generating electricity, displacing coal, they often tout its climate benefits as a cleaner burning fuel. However, research shows that if leaks of methane, which is a more potent but shorter-acting climate pollutant compared to carbon dioxide, are not curtailed, the climate benefits of natural gas can be dramatically lessened or negated entirely.

O'Connor, from EDF, said this single leak is "undermining years of progress" in containing methane leaks throughout California oil and gas facilities. The amount of emissions from this one leak, for example, are now bigger than the combined annual emissions from California's oil and gas infrastructure, including oil refineries.

O'Connor said the state has brought in an array of experts to try to help put a stop to the leak, including people from national energy laboratories and those with experience fighting the BP Deepwater Horizon disaster in the Gulf of Mexico in 2010.

The leak should spur national action to ensure that safety measures are in place at all natural gas storage facilities in order to prevent another similar event, O'Connor added.

“This story… about Aliso Canyon is one that is specific to California, but this canyon represents a bigger problem. This event is the sort of embodiment of... why we need comprehensive methane regulations from oil and gas infrastructure,” he said.

“You can prevent these kinds of things from happening.”