Heavy rains were due to bring fresh misery to Northern California late on Nov. 20, raising the risk of mudslides in an area where people left homeless by the state’s deadliest wildfire huddle in parking lot encampments.
State officials warned people to be alert to the risk of sudden flows of debris down the scorched, denuded slopes of the foothills of the Sierra Nevada mountains.
“Although wildfire damage can be immeasurable, the danger is not over after the flames are put out,” the California Department of Forestry and Fire Protection (Cal Fire) said in a statement on Nov 20.
The remains of 79 victims have been recovered since the Camp Fire erupted on Nov. 8 and largely obliterated the town of Paradise, a community of almost 27,000 people about 175 miles north of San Francisco. The Butte County Sheriff’s Office has tentatively identified 64 of the victims.
The missing persons list kept by the sheriff’s office still had 699 names on it as of the night of Nov. 19. That number has fluctuated dramatically in the past week as additional people were reported missing or as some who were initially listed as unaccounted for are found or are identified among the dead.
Sheriff Kory Honea has said some people have been added to the list more than once at times under different spellings of their names.
As of early on Nov. 20, the fire had torched more than 151,000 acres of parched scrub and trees, and incinerated about 12,000 homes, Cal Fire said. Containment lines have been built around 70 percent of its perimeter, according to Cal Fire.
Efforts to suppress the flames were likely to benefit from a storm expected to dump as much as four inches of rain north of San Francisco between Nov. 20 and Nov. 23.
Smoke from the fire has led to school closures in the region. Citing poor air quality, schools and colleges in the Sacramento area will be shut until Nov. 26.
Flights in and out of San Francisco also have continued to experience some delays or cancellations because of the smoke.
‘Muddy, Mushy Mess’
But heavy showers risk setting off mudslides in newly burned areas, while also making it more difficult for forensic teams sifting through cinders and debris for additional human remains. Colleen Fitzpatrick, the founder of the California-based consulting company Identifinders International, said rain would turn the site into a “muddy, mushy mess” slick with wet ash.
Pathologists from the University of Nevada–Reno worked through the weekend as firefighters peeled back debris, collected bits of burned bones and photographed anything that might help identify victims.
Intense fire over the slopes of canyons, hills, and mountains makes them more prone to landslides, by burning away vegetation and organic material that normally holds soil in place. The fire also creates a hard, waxy surface that tends to repel rather than absorb water.
The result can be heavy runoff of rainwater mixed with mud, boulders, trees, and other debris that flows downhill with tremendous force, said Jason Kean, a research hydrologist for the U.S. Geological Survey.
“Those debris flows have the consistency of wet concrete and move faster than you can run,” he said. “It’s like a flood on steroids … and a big one can take out two-story buildings.”
The number of residents needing temporary shelter was unclear, but as many as 52,000 people were under evacuation orders at the height of the firestorm last week.
Nearly 500 miles south of Paradise near Malibu, west of Los Angeles, at least two inches of rain is expected to fall on the scene of a second blaze, the Woolsey fire, which has left three people dead. That blaze was 96 percent contained as of the evening of Nov. 19.
“Mud and debris flows are a very realistic threat,” the Woolsey Fire Unified Commanders, a state coalition of fire and law enforcement agencies, said in a statement on Nov. 20.
The cause of both fires is under investigation but electric utilities reported localized equipment problems around the time they broke out.
PG&E Corp has said it could face liability that exceeds its insurance coverage if its equipment were found to have caused the Camp Fire.
By Brendan O’Brien in Milwaukee