EXPLAINER: Tackling threat of mudslides in soaked California

SAN DIEGO (AP) — Relentless storms from a series of atmospheric rivers have saturated the steep mountains and bald hillsides scarred from wildfires along much of California's long coastline, causing hundreds of landslides this month.

So far the debris has mostly blocked roads and highways and has not harmed communities as in 2018 when mudslides roared through Montecito, killing 23 people and wiping out 130 homes.

But more rain is in the forecast, increasing the threat.

Experts say California has learned important lessons from the Montecito tragedy, and has more tools to pinpoint the hot spots and more basins and nets are in place to capture the falling debris before it hits homes. The recent storms are putting those efforts to the test as climate change produces more severe weather.

WHY IS CALIFORNIA PRONE TO MUDSLIDES?

California has relatively young mountains from a geology standpoint, meaning much of its steep terrain is still in motion and covered in loose rocks and soil that can be sloughed off easily, especially when the ground is wet, according to geologists.

Almost all of the state has received rainfall totals of 400% to 600% above average since Christmas, with some areas receiving as much as 30 inches of precipitation, causing massive flooding. The severe weather has killed at least 19 people since late December.

Since New Year’s Eve, the California Department of Conservation’s landslide mapping team has documented more than 300 landslides.

The state's prolonged drought has made matters worse.

Dan Shugar, an associate professor of geoscience at the University of Calgary, said drought can have a counterintuitive effect when combined with the incredible rainfall California has seen in recent days.

“You’d think if the ground is dry it should be able to absorb a...