NR 2005-29
December 28, 2005

Contact: Ed Wilson
Mark Oldfield
Don Drysdale
(916) 323-1886


SACRAMENTO – The Department of Conservation (DOC) today urged residents to watch for potential landslide warning signs and exercise safety precautions as California enters the rainy season. Residents whose homes are on or below slopes need to check for the signs of impending landslides and contact local authorities about any landslide concerns.

“Most Californians are aware that we live in earthquake country, but landslides can be every bit as dangerous as temblors,” said State Geologist Dr. John Parrish, head of DOC’s California Geological Survey. “Fortunately, unlike earthquakes, landslides sometimes give warning signs that residents can identify in order to protect the safety of their homes and families.”

A landslide is any mass of earth and rock that moves downhill by sliding, flowing or falling. Large, slow-moving landslides composed of bedrock can cause extensive property damage but usually do not result in loss of life. Debris flows, commonly called mudslides, are more dangerous types of landslides because they can move very quickly before people have a chance to get out of harm’s way. Mud, rock and debris caught by these rapid flows can travel from 10 mph to 100 mph.

“If you live in an area where there was considerable rain last year, you’re more susceptible to landslides this winter,” said Parrish. “Once the heavy rains begin, and the rainfall is three-to-four inches a day or a quarter inch an hour, the soil becomes waterlogged and may trigger mudslides. Residents should be on the lookout for location-specific warnings from local and state agencies.”

When California rainfall exceeds normal levels by 150 percent or more, landslides cause, on average, property damage in excess of $100 million and as many as five deaths each year. In January 2005, heavy rainfall contributed to landslides that claimed 10 lives in Ventura County and caused tens of millions of dollars in damage around the state.

Californians who live on slopes or in areas that have experienced landslides in the past can take some of the following steps to protect their homes and families from damage:

♦ On rainy nights, the single most important precaution is to avoid sleeping in lower-floor bedrooms on the sides of houses that face hazardous slopes. In California, most of the deaths caused by debris flows have occurred when people sleeping in these positions were buried by debris.

♦ Monitor rainfall during intense rainstorms, and install a plastic rain gauge where it can be checked frequently.

♦ Consider hiring an engineering geologist to evaluate your property.

♦ Plant vegetation and install engineered drainage systems on slopes, and consider constructing properly designed diversion walls to deflect debris flows.

♦ Check for new cracks in the soil, structural shifts, holes or bare spots on hills, tilting trees, bulges at the base of slopes, or material moving downhill.

♦ Watch for new springs or seeps and excess surface erosion around your property. Identify if any nearby streams appear muddier than normal.

♦ Listen for unusual rumbling sounds and noises that may indicate moving earth and rocks, breaking vegetation or structures, or that pipes are being pulled apart.

The California Geological Survey provides technical information and advice about landslides, erosion, sedimentation, and other geologic hazards to the public, local governments, agencies and industries that make land-use decisions in California. More information about landslides, including landslide maps and mitigation steps, can be found here.

In addition to, mapping and studying earthquakes and other geologic phenomena, the Department of Conservation classifies areas containing mineral deposits; ensures reclamation of land used for mining; regulates oil, gas and geothermal wells; promotes beverage container recycling; and administers agricultural and open-space land conservation programs.