According to the reports of Monday (20 January), Recent wildfires in Los Angeles (LA), particularly the Palisades and Eaton Fires, have devastated large areas, burning over 15,300 hectares and destroying 12,000 structures, claiming at least 27 lives. While firefighters continue working to contain the blazes, experts are now warning that the charred hill slopes left in the wake of the fires are highly vulnerable to landslides and debris flows. These hazards are exacerbated by the fragile nature of the soil after the fires, which has become susceptible to further erosion, even without rain.
The risk of landslides is particularly high in areas such as Pacific Palisades, where a home was split in two by a landslide made up of wildfire debris. LA County officials have expressed concerns about the dangers posed by these fragile slopes, urging residents to remain cautious. Hydrologists warn that landslides may occur even without rainfall, triggered by the dry movement of particles known as “dry ravel” on steep slopes.
The U.S. Geological Survey (USGS) has raised alarms about the potential for runoff-generated debris flows in the aftermath of the fires, especially in areas with steep terrain and exposed soil. Experts suggest that the risk of post-fire debris flows is highest in the first two years after fires, but shallow landslides could occur later as vegetation begins to recover. These debris flows are often triggered by high-intensity rainfall over short periods, which can lead to flash floods.
In the wake of these threats, authorities are closely monitoring the situation and have developed infrastructure to mitigate damage, including debris basins in vulnerable areas. Despite these efforts, experts acknowledge the ongoing stress faced by residents who are already dealing with the aftermath of the fires. With the threat of additional landslides over the next few years, authorities are working to evaluate hazards and issue warnings when conditions are right for dangerous debris flows.
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