On Thursday afternoon, firefighters in Santa Barbara arrived on a hill where flames and smoke were visible from a hole in the rocks.
The so-called “Hope Ranch Volcano” – as locals know it – had re-ignited, and it took hours for crews to extinguish the massive fire and hot spots.
But experts say that description doesn’t explain exactly why the region erupts regularly — at least, geographically.
No, it’s not a volcano, and while firefighters often call the spot a “natural solfatara,” geologists say that’s not quite right.
“It’s spontaneous combustion,” said James Boles, professor emeritus in UC Santa Barbara’s Department of Earth Sciences.
When Earth’s layers of rocks move, oxygen can interact with volatile compounds in the rocks – including iron sulfide – producing a lot of heat during the oxidation process. That heat, under the right conditions, can increase so rapidly and so much that organic matter in the area begins to spontaneously combust.
“The same thing happens every two years,” Boles said. And although it may look like a small volcano, it is far from that.
The region has seen such flare-ups since the 1800s, according to a post by Santa Barbara County Fire Department.
On Thursday, firefighters said the incident caused a smoldering fire in an underground PVC drainage pipe, as well as large flames and smoke billowing down the hill, the fire department said. Crews were able to stop the fire from spreading without damaging any structures.
The department referred to the natural process that caused the fire as “solfatara”, a natural volcanic steam vent that releases sulfurous gases. The term is derived from? a special volcanic region of Italy. And while sulfur gases are likely coming from the Hope Ranch rock, Boles said there is no underlying volcano, making the designation not exactly accurate.
Interestingly, Hope Ranch is not alone.
On the coast of Ventura County, locals have dubbed the geyser-like geologic formation “Rincon Volcano”, but this also appears to be a case of misnomer.
At this location, several hundred feet above the 101 Freeway between La Conchita and Rincon Point, this area also has spontaneously combusted during ground shifts, according to earlier reporting by The Times.
According to the Carpinteria Valley Museum of History, the first recorded report of that “steaming mountain” was made in 1835 by a man traveling north by stagecoach to Lompoc.
Boles said similar processes can occur in different places, but certain rock formations are particularly sensitive to… explosionif you will.
It is worth noting that although there are currently no major volcanoes located off the coast of California. Many across the state.
