Probabilistic Tsunami Hazard Analysis: Multiple Sources and Global Applications

International audienceApplying probabilistic methods to infrequent but devastating natural events is intrinsicallychallenging. For tsunami analyses, a suite of geophysical assessments should be in principle evaluatedbecause of the different causes generating tsunamis (earthquakes, landslides, volcanic activity,meteorological events, and asteroid impacts) with varying mean recurrence rates. Probabilistic TsunamiHazard Analyses (PTHAs) are conducted in different areas of the world at global, regional, and local scaleswith the aim of understanding tsunami hazard to inform tsunami risk reduction activities. PTHAs enhanceknowledge of the potential tsunamigenic threat by estimating the probability of exceeding specificlevels of tsunami intensity metrics (e.g., run-up or maximum inundation heights) within a certain period oftime (exposure time) at given locations (target sites); these estimates can be summarized in hazard mapsor hazard curves. This discussion presents a broad overview of PTHA, including (i) sources and mechanismsof tsunami generation, emphasizing the variety and complexity of the tsunami sources and their generationmechanisms, (ii) developments in modeling the propagation and impact of tsunami waves, and (iii)statistical procedures for tsunami hazard estimates that include the associated epistemic and aleatoricuncertainties. Key elements in understanding the potential tsunami hazard are discussed, in light of therapid development of PTHA methods during the last decade and the globally distributed applications,including the importance of considering multiple sources, their relative intensities, probabilities ofoccurrence, and uncertainties in an integrated and consistent probabilistic framework