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|Title: ||Tsunami hazard induced by a newly discovered landslide in the Tagus delta off Lisbon (Portugal)|
|Authors: ||Ramalho, Inês|
|Keywords: ||Tsunami hazard|
|Issue Date: ||2019|
|Citation: ||Geophysical Research Abstracts
Vol. 21, EGU2019-8677, 2019
EGU General Assembly 2019|
|Abstract: ||Deltas are sedimentary bodies with high sedimentation rates that are very sensitive to changes in environmental
conditions. The Tagus delta off Lisbon (Portugal) is characterized by the presence of high energy deposit and erosive structures with an estimated age of approximately 8 ky BP. In this work, we investigate, through numerical
modelling, the tsunami hazard induced by a newly discovered underwater landslide at the Tagus delta. The Tagus
delta landslide is more than 9 km of length (parallel to the delta front) and more than 3 km of width with a maximum thickness of ∼20 m with a volume of approximately 0.27 km3.
To model the landslide downslope movement and its induced tsunami we employed a Bingham visco-plastic model
coupled to non-linear shallow water equations. The numerical simulations are performed over a high-resolution
paleo-bathymetry that allows evaluating the tsunami hazard at the time of the landslide failure. We constructed
the paleo-bathymetric model of the Tagus delta taking into consideration the sedimentation rates, the age of the
landslide, and the paleo mean sea level. Additionally, we evaluate the tsunami hazard resulting from the occurrence
of a similar-size Tagus landslide at the present-day bathymetric and sea-level conditions.
Results show that landslides at the Tagus delta pose a significant tsunami hazard to the surrounding coasts, particularly in Lisbon. Therefore, more attention must be given to shallow water submarine landslides and their induced
tsunamis in the marine Geo-hazards assessment of the region.
This work is supported by the FCT funded projects: MAGICLAND - MArine Geo-hazards InduCed by underwater LANDslides in the SW Iberian Margin (Ref: PTDC/CTA-GEO/30381/2017), TAGUSGAS - Tsunami
hazard assessment of the Lisbon city associated to the Tagus delta landslide (Ref: PTDC 2017 - PTDC/CTAGEO/31885/2017), and TagusDelta - 3D high-resolution seismic stratigraphy of the Tagus Delta – imaging of
tsunami and earthquake evidence for natural hazards assessment (Ref: PTDC/MAR/113888/2009).|
|Appears in Collections:||ICT - Comunicações - Em Congressos Científicos Internacionais|
GEO - Comunicações - Em Congressos Científicos Internacionais
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