A wetter and warmer Alaska means dangerously slippery slopes

By Victoria Petersen

An hour before sundown on Dec. 2, Lilly Ford and her family heard a “strange, low rumble” outside of her home in Haines, Alaska. It lasted about a minute as a 600-foot-wide slurry of timber, mud, soil and debris cascaded down a nearby mountain, through a residential area, and into the ocean. “I couldn’t believe the mountain had swept people and houses away just like that — ripped the ground out from under them,” Ford said. “It’s just not something you’d ever anticipate.”

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Landslides are a growing threat as warm, heavy rainstorms — intensified by climate change — flush rock, soil, trees and debris down slopes onto the land below. In response to deadly landslides across the West, scientists and communities are calling for more resources to better prepare and understand the looming threat. On Dec. 16, Congress heeded that call by passing legislation that will identify the most vulnerable communities and devise emergency plans and warning systems to protect them.

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While landslides are nearly impossible to predict, there are ways to identify the areas at greatest risk and monitor the most hazardous slopes. Landslides are triggered by a number of weather, geologic or human factors, but America’s most frequent and damaging landslides are induced by prolonged or heavy rainfall, especially in areas with steep slopes, wildfire burn scars, or a history of landslides.

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Without detailed maps, and the baseline support data needed to make them, identification of landslide-prone areas will remain insufficient, and any decisions about possible hazards will be much less informed, Wolken said. “Ultimately, that’s what it’s going to take: the money to be able to collect the data, to be able to make the assessments, to even begin to understand what the magnitude of the problem is,” Stevens said. “We really need to do something about this because this is not going to be the last event.”