The Los Angeles wildfires were still burning when scientists started scouting the freshly charred burn scars to search for signs of another danger that’s yet to come — roaring torrents of rock and mud and water that can sweep downhill with deadly momentum.
Triggered by intense bouts of rainfall, these debris flows — as well as flash floods — become more likely to occur after an intense wildfire has scorched an area’s slopes and vegetation. While flash floods can be devastating, debris flows surge with even greater ferocity. At least half of their volume is sediment, and it’s mixed with burned trees, cars and boulders.