Landslide fears mount in Orange County communities built on hillsides as heavy rain is expected
Orange County communities built on hillsides are preparing for a powerful winter storm to move through Southern California.
Sandbags and tarps have been laid out in some areas to protect slopes from the rain.
The moisture could trigger landslides, especially in recently burned areas.
MAP: LA burn scar areas under evacuation warnings due to storm
"You can imagine soil gets muddy, and it's much easier for one layer on top of the other to slide off a slope," Civil Engineering professor at UC Irvine Anne Lemnitzer said.
"Due to the loss of vegetation, which is one natural solution to provide stabilization of the slope. And also the lack of any drainage system there; those areas that are now dried and that are burned are really easy for those to slide down," she added.
Lemnitzer said there are two types of land movement.
"We see those types of landslides in either surficial form where it only happens at the surface or we can see deeper seeded landslides where the soil loses its strength, and then it slides down as a whole mass," she said.
Strongest storm of the season moving into SoCal. Here's when the heavy rain will arrive
There are signs homeowners in vulnerable areas can look for.
"If you see slide movements in an initially flat area, you see cracks in your soil and you have a slope adjacent; this is typically an indicator that there's some movement along the slope," Lemnitzer said.
She recommends using tarps to cover up specific spots but warns this is only a temporary solution.
"It would prevent an immediate direct infiltration of the water onto the ground surface," she said. "So the tarping could be an effective short-term solution, but in the long term it does not because the water also comes in from the sides, from the top and from behind. And you can't prevent that."
Residents are being asked to stay on high alert and have a bag packed so they can be ready to go in case they need to evacuate.
