Two days before Christmas reports of a natural gas leak spread throughout the South Bay. Calls went out to 911 emergency services in El Segundo, Manhattan Beach and Hermosa Beach.
In Redondo Beach, dispatch operators fielded more than 100 phone calls about a sulfuric-like smell, said Jason Kilpatrick, communications supervisor with the Redondo Beach police.
So what was that strange odor?
Kilpatrick said it came from the ocean and it happens a couple of times each year. He can remember at least three occurrences this year. Fire department veterans said it’s been occurring for the past 20 years, according to Kilpatrick.
“We’ll suddenly be inundated with so many 911 calls with residents reporting gas leaks,” Kilpatrick said. “Eventually it’s determined because it’s so widespread that it’s something from the ocean.”
What exactly causes the smell is unclear. Sulfur compounds are typically added to natural gas, so many residents thought there was a gas leak. But it wasn't that.
Two oceanographers, both professors at University of Southern California, had similar, but slightly different explanations.
Professors Doug Capone, PhD, and Jed Fuhrman, PhD, said what people might be smelling is hydrogen sulfide associated with several possible sources such as oil seeps or rotting seaweed.
“We do have hydrocarbon seeps along the coast, for example around Palos Verdes and White's point, which could be a source of sulfide,” Capone wrote by email.
Fuhrman suggested the smell could be the result of rotting plant matter that deprived seawater of oxygen and somehow rose to the surface.
“Anaerobic seawater (relatively deep and isolated from the air by stratification) can smell similar to that, and sometimes the stratification breaks down, causing this smelly water to reach the surface,” Fuhrman wrote by email.
There is another condition, not to be confused with what occurs locally called “ocean burps,” which scientists have indicated could be a sign of increased global warming. Capone explained that while it’s similar, there is no evidence to suggest that a methane release is what has been occurring locally. Besides, they say, methane is odorless.
“Methane hydrates or ‘clathrates’ are solid forms of methane that exist in the deep sea under high pressure and cold temperature,” Capone wrote. “When they warm up and ‘melt’ back to a gas, some researchers have suggested they could cause sudden ocean burps (and explosions). I'm not aware of clathrate deposits in local coastal waters.”
In Hermosa Beach, firefighters are familiar with determining whether the source of a suspicious smell is something related to a spill or an ecological issue, said Sgt. Mick Gaglia with the Hermosa Beach Police Department.
“When they get multiple calls and there is a stench in the air and there is no known cause, they surmise it comes from the ocean,” Gaglia said. “We had that on-shore breeze pushing the smell inland. The fire department said it usually encompasses a few cities, so it makes sense.”