Oral Presentation

Submarine mass movements can take a wide variety of forms, such as translational slides, rotational slumps, and debris flows, and each will have different tsunamigenic efficiency. Existing methods for assessment of landslide tsunami hazards rely on the determination of a “design scenario” as inferred from existing data, known sources, and expert judgment. This scenario typically examines a single slide volume, moving down a single prescribed failure plane, approximated with just one motion or rheology model. Movement towards a probabilistic approach for landslide tsunamis has been hindered largely because of a lack of any guidance on how to include landslide tsunami sources, which are characterized by significant natural variability and uncertainty. This presentation will discuss progress to-date in a California study whose objective is to develop a probabilistic method to include this variability and uncertainty for landslide tsunamis. The presentation will provide an inventory of known tsunamigenic submarine mass movements that might impact the California coastline, and will highlight offshore areas where there are apparent gaps in the historical record. With this information, our task is to develop a complete logic tree to aggregate hazard curves from all methods utilized by the larger technical community. The primary benefit of this effort would be a framework for probabilistic assessment of tsunami hazards at design probabilities appropriate for coastal structure design and evacuation planning.