NATIONAL-SCALE LANDSLIDE HAZARDS MAPS AND ANALYSIS ACROSS THE UNITED STATES: INVENTORIES, SUSCEPTIBILITY, EXPOSURE, AND DAMAGE (Invited Presentation)

Mapping of landslide locations is fundamental to understanding the controls on their occurrence and for informing risk reduction strategies. The U.S. Geological Survey (USGS) maintains and updates an extensive national compilation of existing landslide inventories, originally collected by state geological surveys, academic researchers, the USGS, and other agencies. We leveraged the 2022 version of this heterogeneous, nation-wide geodatabase, with over 613k landslide points and polygons, to develop a new landslide susceptibility map with uniform coverage over the coterminous U.S. (CONUS), Alaska, Hawaii, and Puerto Rico. This 90-meter resolution map distinguishes areas that are potentially susceptible to landslides from those areas with negligible susceptibility, based on a parsimonious slope-relief threshold derived from the USGS national digital elevation model (~10 meters). We also introduce a novel susceptibility classification scheme that leverages the down-sampling information from our 10-m analysis to show variability in landslide potential with the 90-m model output. We independently tested our new map using four additional statewide inventories, totaling 172k landslides. We found that the resulting map is more transparent and performs better over CONUS than existing landslide susceptibility models with coverage over the U.S. and globally. The national susceptibility map is not intended to supplant any locally developed susceptibility or hazard assessment products. Instead, it provides an improved nation-wide overview using a systematic and objective approach, which is inherently generalized, but may be useful in areas without state-wide or local-scale landslide assessments. The 2024 version of the inventory compilation is approaching one-million landslides and the susceptibility map has opened new possibilities for further national-scale investigations, from compiling estimates of damage and impacts to analysis of landslide exposure across the country. This presentation will focus on the development and evaluation of our new susceptibility map, its advantages and limitations, the value of statewide landslide inventories, and potential applications.