California has worked to add tools to protect against mudslides, including pinpointing hot spots, creating basins and placing nets to capture falling debris before it hits homes.
On Jan. 9, 2018, intense rain fell on a weeks-old wildfire burn scar in the mountains above Montecito on the Santa Barbara County coast, unleashing huge torrents that tore through the community, killing 23 people and destroying or damaging hundreds of homes.
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.
One of the best ways to manage landslides is with debris basins — pits carved out of the landscape to catch material flowing downhill that the U.S. Geological Survey says can reach speeds exceeding 35 mph (56 kph).
Often located at the mouths of canyons, the basins collect debris while allowing water to continue downstream, according to Los Angeles County Public Works.
