Investigators searching for the cause of an oil pipeline rupture off the Southern California coast have pointed to the possibility that a ship anchor dragged the line across the seabed and cracked it.
However, two videos released so far provide only tantalising clues about what might have happened to the pipeline, owned by Amplify Energy, 100ft below the ocean surface, causing tens of thousands of gallons of crude oil to spill off the famed surf breaks of Huntington Beach.
A US coast guard video appears to show a trench in the seafloor leading to a bend in the submerged line, but experts offered varied opinions of the significance of the brief, grainy shots.
An earlier video revealed a 13in rupture in the line, but the pipe showed no evidence of damage that they said would be expected from a collision with a multi-tonne anchor from cargo ships that routinely move through the area off the ports of Los Angeles and Long Beach.
The slight bow in the line displayed in one video “doesn’t necessarily look like anchor damage,” according to Frank G Adams, president of Houston-based Interface Consulting International.
When a pipeline is hit by an anchor or other heavy object, “that typically results in physical damage that may lead to a fracture”.
Ramanan Krishnamoorti, a petroleum engineering professor at the University of Houston, said he considered the video that runs along a bend in the line “revealing”.
“It seems to me you’ve got something that was dragged in the sand that might have impacted the pipeline,” he said.
However, he remained puzzled that the leak came from a crack and not a larger gash, assuming it was hit by an anchor or some other object.
Key questions remain: Could the line have been hit days before the leak started? What ship is responsible? And if a ship anchor is not the culprit, what else could it be?
Investigators, meanwhile, continued to hunt for the cause of the break that spilled tens of thousands of gallons of crude oil off the famed surf breaks of Huntington Beach, as well as determining what happened in the crucial early hours after reports of a possible oil spill first came in.
The 13in rupture seen in one video could explain why signs of an oil slick were seen last Friday night, but the spill eluded detection by the pipeline operator until Saturday morning, experts said.
Amplify Energy, a Houston-based company that owns and operates three offshore oil platforms and the pipeline south of Los Angeles, said it did not know there had been a spill until its workers detected an oil sheen on the water on Saturday at 8.09am local time.
The cause of the spill is under investigation by numerous agencies as the clean-up continues along miles of shoreline on the Orange County coast south of the sister ports.
On Thursday, the US coast guard slightly revised spill estimates to at least about 25,000 gallons and no more than 132,000 gallons.
The US coast guard said it is investigating the incident with other agencies as a “major marine casualty” due to the potential involvement of a vessel and damages exceeding 500,000 dollars (£367,000).
It said they will determine if criminal charges, civil penalties or new laws or regulations are needed.
