GSA News Release: New Geosphere Study Examines 2017–2018 Thomas Fire Debris Flows

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GSA's news release on the recent USGS-authored publication from the Landslide Hazards Program: Inundation, flow dynamics, and damage in the 9 January 2018 Montecito debris-flow event, California, USA: Opportunities and challenges for post-wildfire risk assessment.

Excerpt:

Shortly before the beginning of the 2017–2018 winter rainy season, one of the largest fires in California (USA) history (Thomas fire) substantially increased the susceptibility of steep slopes in Santa Barbara and Ventura Counties to debris flows. On 9 Jan. 2018, before the fire was fully contained, an intense burst of rain fell on the portion of the burn area above Montecito, California. The rainfall and associated runoff triggered a series of debris flows that mobilized ~680,000 cubic meters of sediment (including boulders larger than 6 m) at velocities up to 4 meters per second down urbanized alluvial fans. The resulting destruction included 23 fatalities, at least 167 injuries, and 408 damaged homes.

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