La Palma landslide tsunami: calibrated wave source and assessment of impact on French territories

Stéphane Abadie (1) , Alexandre Paris (2) , Riadh Ata (3) , Sylvestre Leroy (4) , Gael Arnaud (5) , Adrien Poupardin (6) , Lucie Clous (1) , Philippe Heinrich (2) , Jeffrey C. Harris (3) , Rodrigo Pedreros (4) , Yann Krien (5)

1 SIAME - Laboratoire des Sciences de l'Ingénieur Appliquées à la Mécanique et au génie Electrique
2 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
3 LHSV - Laboratoire d'Hydraulique Saint-Venant / Saint-Venant laboratory for Hydraulics
4 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
5 LARGE - Laboratoire de Recherche en Géosciences et Energies [UR2_1]
6 IRC - Institut de Recherche en Constructibilité

In this paper, we present new results on the potential La Palma collapse event, previously described and studied in Abadie et al. (2012). Three scenarios (i.e., slide volumes of 20, 40 and 80 km 3) are considered, modeling the initiation of the slide to the water generation using THETIS, a 3D Navier-Stokes model. The slide is a Newtonian fluid whose viscosity is adjusted to approximate a granular behavior. After 5 min of propagation with THETIS, the generated water wave is transferred into FUNWAVE-TVD (Total Variation Diminishing version of FUNWAVE) to build a wave source suitable for propagation models. The results obtained for all the volumes after 15 min of Boussinesq model simulation are made available through a public repository. The signal is then propagated with two different Boussi-nesq models: FUNWAVE-TVD and Calypso. An overall good agreement is found between the two models, which secures the validity of the results. Finally, a detailed impact study is carried out on La Guadeloupe using a refined shallow water model, SCHISM, initiated with the FUNWAVE-TVD solution in the nearshore area. Although the slide modeling approach applied in this study seemingly leads to smaller waves compared to former works, the wave impact is still very significant for the maximum slide volume considered on surrounding islands and coasts, as well as on the most exposed remote coasts such as Guadeloupe. In Europe, the wave impact is significant (for specific areas in Spain and Portugal) to moderate (Atlantic French coast).

Domaines: Planète et Univers [physics]

Stéphane Abadie, Alexandre Paris, Riadh Ata, Sylvestre Leroy, Gael Arnaud, et al.. La Palma landslide tsunami: calibrated wave source and assessment of impact on French territories. Natural Hazards and Earth System Sciences, 2020, 20 (11), pp.3019-3038. ⟨10.5194/nhess-20-3019-2020⟩. ⟨hal-03011158⟩