In the last few days, several regions in the Golden State were impacted by landslides, including Glendora, a community East of Los Angeles, and Camarillo in Ventura County.
Previously, the two areas suffered extensive wildfire damage -- Glendora suffered wildfire devastation in the Colby fire last January, and Camarillo was hit by massive wildfire damage in May of 2013.
It is the hillside areas that have endured wildfires that are most likely to subsequently experience landslides and mudslides, according to the California Department of Public Health.
In the aftermath of a hillside wildfire, where trees and brush are burned and destroyed, few roots remain to hold soil in place. The heat and the flames create a slippery top layer to the earth that remains -- that layer creates a path for rapidly rushing water to race downhill.
When rain falls at a rate of one inch or more per hour, as it has in the last few days in California, the force is strong enough to carry large rocks and boulders to the ground below, crushing anything in its path.
Areas where wildfires or construction have destroyed vegetation on slopes are at high-risk landslides during and after heavy rains, according to the California Department of Public Health's website.
Landslides and mudslides account for 25 to 50 deaths a year and rapidly moving debris can result in human trauma, broken lines that can cause injury or illness and disrupted roadways and railways that can endanger travelers.
In Camarillo, the landslides knocked down barriers that crews had established to protect residents and debris piled up as high as the homes in Camarillo Springs. An estimated 18 homes there were marked as uninhabitable.
While no injuries were reported in Glendora, a flow of debris carried rocks, bricks and sticks down the suburban streets in the Los Angeles suburb. Slides in several other inland Southern California areas led to evacuations.
State officials urge residents living near hillsides to be prepared as more rain is expected to fall in California.