Climate change is driving more volatile precipitation patterns around the world – very dry stretches punctuated by storms that drop large amounts of rain or snow in a short amount of time. While wetter and drier spells may have certain effects that are easy to predict, such as on water levels in lakes and rivers, a recent study focused on California reveals that they can affect slow-moving landslides in unanticipated ways.
The researchers expected slow-moving landslides – where land creeps downhill just inches to feet in a year – in bone-dry Southern California to behave differently from those in rainy Northern California when exposed to heavy precipitation and drought conditions. But that wasn’t the case. The study authors found that landslides in wetter and drier regions of California showed similar sensitivity to precipitation extremes, moving on average faster and farther downhill during rainy periods compared to drought years.
Water triggers landslides, and knowing how landslides react to record drought or extreme rainfall can help researchers better predict their future behavior, including whether any could collapse, or fail catastrophically. The big-picture goal is to develop a statewide inventory of landslide behavior that would inform a monitoring network. While slow-moving landslides don’t necessarily pose an immediate danger to people or infrastructure, over time they can damage things like roads and buildings. And in some instances, they can suddenly collapse, which is what occurred with the Mud Creek landslide near Big Sur in 2017.
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