What caused the Chevron blast? Experts have theories

Size of the massive fire at El Segundo refinery raises concerns about what went wrong. Investigations are underway.

- BY GRACE TOOHEY AND KAREN GARCIA

FIREFIGHTERS work to extinguish the smoldering fire Friday morning at Chevron's El Segundo refinery.

The focus of the investigation into what caused a massive explosion and fire last week at Chevron's El Segundo plant has turned to a jet fuel processing unit in the southeast corner of the sprawling oil refinery.

Chevron officials have said little about what caused the blast but confirmed the Isomax unit, which converts oil into higher-value products such as jet fuel, remains shuttered since the inferno even as other refinery operations continue.

"Until we can figure out everything that happened here and make sure it doesn't happen again, we won't restart it," said Ross Allen, a Chevron spokesperson, adding that the refinery continues to produce jet fuel, as well as gasoline and diesel, from other units.

Although refinery fires are not unheard of Chevron's onsite firefighting team specifically prepares for them — industry experts say the sheer scale of the El Segundo fire last week raises concerns about what went wrong and requires a thorough investigation. The blast turned the night skies across the South Bay bright orange and sent out a roar that reverberated for miles. No one died in the incident, and damage was confined to the refinery's footprint. Only a few workers have reported minor injuries.

"I think Chevron has been extremely, extremely lucky ... [given] the size of the explosion here," said Najmedin Meshkati, a professor of engineering at USC who has served as an expert for the U.S. Chemical Safety and Hazard Investigation Board as it has probed other major refinery fires.

Meshkati and several other experts interviewed by The Times said it was still hard to know exactly what led to the El Segundo fire that night as few details have been shared by local or Chevron investigators, but there are some likely culprits.