SPATIOTEMPORAL PROPERTIES OF LANDSLIDES IN THE PACIFIC NORTHWEST

Quantifying changes to landslide behavior has been difficult because landslide inventories are spatially limited and temporally inconsistent. The Pacific Northwest region (Washington and Oregon) has some of the best landslide inventories in the U.S., and is also highly susceptible to landslide events. Furthermore, future climate projections, such as from the National Climate Assessment, suggest that this region may experience more extreme precipitation in a changing climate. This work presents a landslide inventory synthesized from data provided by state and local agencies in Washington and Oregon, a global landslide catalog, and other literature. The new inventory includes both spatial and temporal information. The space and time patterns of landslide frequency in this region were analyzed over several decades, as well as the co-occurrence of extreme daily, seasonal and annual rainfall. This work is part of a larger project on changes to precipitation means and extremes, soil moisture, snow cover, and the resulting impacts on landslide hazard and exposure over months, years and decades within this region.