The LA Times reports a curious local phenomenon.

A patch of land in Ventura County’s section of Los Padres National Forest where the ground recently heated up to 812 degrees continues to puzzle firefighters and geologists after weeks of monitoring.

“It’s a thermal anomaly,” said Ron Oatman, spokesman for the Ventura County Fire Department.

Firefighters responded to reports of a blaze there a month and a half ago, when observers noticed smoke rising from the parched scrub. But when they arrived, they found no flames.

Firefighters and geologists who have surveyed the area in the Sespe Oil Field are uncertain what’s causing the heat, but they do have a theory.

Allen King, a retired geologist with the U.S. Forest Service who went to the site Friday, said the smoking ground is “a normal occurrence” that does not appear to be the result of human activity.

The hot spot is in an area considered to be an active landslide that has shifted for more than 60 years. Several hundred feet below its cracked surface lie pockets of gas, tar and oil.

King said he suspects cracks along the landslide’s slope allow oxygen to enter into the earth and hydrocarbon material to “seep out” of the fine-grain shale. The combination can create underground combustion, he said.

King said the depth at which hydrocarbon material can be found “varies tremendously” and that he does not know at what depth the combustion in the oil field is occurring. The 812-degree temperature was measured Friday about a foot below the surface, he said. No other temperature checks have been made since, according to Oatman.

During Friday’s visit to the hot spot, smoke rose through five cracks in the ground. From a distance, it looked like “a small, smoldering camp fire,” Oatman said. The smoke comes and goes, he said, and fire officials expect it will last until the next heavy rainfall, when water and mud plug the fissures.

Mr. King says similar high temperatures have been recorded at that location five times since 1987.