Speaker: Ivana Bosnic​ (Instituto Dom Luiz, FCUL).

Abstract: The 1755 Lisbon earthquake triggered the largest historical tsunami ever registered in Western Europe. Despite recent efforts to better understand this event, there are still unanswered questions mainly regarding its source, magnitude and flow characteristics. This work aims to enrich this discussion by presenting innovative results that contribute to constrain the source and provide a more accurate determination of the onshore flow characteristics. The groundbreaking element of this study relies on the methodology applied that focus on the onshore sedimentary imprints left by the tsunami inundation. Sediments are used to quantify the tsunami flow characteristics (inverse modeling) through high-resolution grain-size analysis. These results are in turn compared to the average onshore flow estimated by a forward model (Delft3D) considering 3 plausible tectonic sources. This modeling approach provides new clues regarding the AD 1755 tsunami likely source with estimated onshore tsunami flow average velocities of about 8 m/s. 

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