Southern California is anticipating substantial rain this week due to a strong atmospheric river, raising the risk of damaging debris flows. Rain is expected to begin on Wednesday, with the most significant threats occurring early Thursday and continuing into Friday. Coastal areas could receive 2-4 inches of rain, while mountainous regions may see over 4-8 inches. Areas such as Santa Barbara and San Luis Obispo counties face a 60% chance of this level of rainfall, with Los Angeles and Ventura counties at 40%.
Landslides pose a significant risk, particularly after wildfires have weakened vegetation that otherwise stabilizes the soil. Heavy rain following a wildfire can lead to rapid erosion and dangerous debris flows. Different types of landslides include mudflows, which consist primarily of mud, and debris flows, which include rocks and other debris. Rainfall rates of 0.5 inches per hour can trigger debris flows in fire-affected areas.
Past incidents have shown the devastating effects of debris flows, including the deadly January 2018 Montecito disaster that killed 23 people. The heightened risk of landslides lasts for several years following a wildfire as vegetation regrows. Deep-seated landslides can occur without recent rain and may show subtle warning signs like cracks in the ground.
Overall, the article highlights the vital connection between heavy rain, wildfire damage, and the subsequent risks of landslides in California’s mountainous terrain.
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