Dangerous debris flows can strike at any time, carrying boulders and cars at speeds up to 35mph.
Newsom issued an executive order to expedite flood control measures before this weekend’s rain] Usually beginning on hills or mountains, debris flows can happen during downpours of just half an inch of rain an hour.
“Even now that the fires are out, looming threats of mud and debris flows are a significant threat to the safety of our communities,” said Los Angeles County Board Chair Kathryn Barger.
After the Thomas fire struck in 2017, a debris flow in Montecito, California, killed 23 people and damaged or destroyed more than 400 homes.
Without vegetation to hold the soil, the runoff flows faster and gains power as it heads downhill, increasing the risk of flash flooding and fast-moving landslides of debris.
