DEVELOPING A GLOBAL INVENTORY OF DISPLACEMENT WAVES FROM SUBAERIAL LANDSLIDES

Rapid landslides entering water bodies generate displacement waves, amplifying the variety and geographic extent of their impacts. Landslide-generated displacement waves may cause devastating near-source effects and damage along tens of kilometres of shoreline. It is thus important to include displacement waves in landslide inventories and hazard assessments. Most research on this phenomenon involves characterization of individual events and, in some cases, comparison of a few events. We have compiled a catalogue of historic events to improve understanding of displacement waves from subaerial landslides and, hopefully, help develop tools for rapid general quantification of associated hazard and risk. The catalogue is based on reviews of published case studies, tsunami catalogues, and the Norwegian national landslide database, as well as discussions with local subject experts from key regions. It currently contains nearly 300 events from the fourteenth century AD to present. Events are concentrated in mountainous areas with long histories of settlement and written recordkeeping. As a result, there are clear spatial biases. In addition, more recent events are better represented than earlier ones. Despite these shortcomings, the inventory provides new insights into the geographic distribution, size, frequency, and range of mechanisms and impacts of landslide-generated displacement waves. Geographic clusters of events likely reflect geologic, physiographic, and tectonic controls, and can help prioritize hazard investigation and mitigation. The diversity of events helps to identify conditions that influence wave effects, such as run-up and travel distance. For instance, large rockslides into narrow lakes and fjords produce the highest run-ups whereas large volcanic debris avalanches and flank collapses into relatively open seas produce the farthest reaching impacts. We hope to stimulate expansion of the catalogue through this contribution, and invite colleagues to help identify and detail additional events.