As the latest El Niño rainstorm moved into Southern California, there were already signs that the combination of rain and gravity was creating problems.

 

Mud and debris flowed onto the 101 Freeway in northern Ventura County in an area that was recently burned in a fire, shutting northbound lanes.

Here are some questions and answers about mudslides.

Debris flow has long been a concern in areas where wildfires have recently burned. Vegetation, once burned, can no longer hold back loose sediment.