HR: 1340h
AN: S53A-1009    [Abstracts]
TI: Tsunami Hazard in Western Mediterranean: Preliminary Study of Scenarios for the Balearic
AU: * Roger, J
EM: jean.roger@cea.fr
AU: Hebert, H
EM: helene.hebert@cea.fr
AF: CEA-DIF/DASE, CEA-DIF/DASE Laboratoire Risques Sismiques et Geologiques BP 12, Bruyeres-le-Chatel, 91680, France
AB: Within the framework of the TRANSFER European project, in order to mitigate tsunami hazard in Western Mediterranean, we aim at producing inundation maps for the bay of Palma (Balearic) using numerical modeling. To this end we build a set of scenarios based on realistic tectonic sources able to generate tsunamis. Such a study has been carried out in order to constrain the source(s) responsible for the destructive Djijelli (Algeria) earthquake of 1856 (estimated I0=VIII MSK). This event produced at least one reported inundation in the Balearic and flooded some sites along the Algerian coast over a wide area. In addition the Palma bay is part of bays which are inclined with rissaga phenomenon (atmospheric tsunami) which supposes particular possible site effects (high resonance for example). Available new bathymetric and seismic data along the North-Algerian margin allowed us to propose a compressive "en échelon" fault system offshore Djijelli as possible candidate for this event. Three faults, each one about 35 km long, have been defined in agreement with the isoseismal map of the quake, and have been tested alone or combined. We choose to model a Mw=7.2 earthquake generated tsunami. A co-seismic slip of 1 to 1.5 m with a pure compressive mechanism has been chosen consistent with a convergence rate of 6mm/y leading to a period of recurrence of about 200-500yr according to bibliography. Wave propagation and inundation models are calculated using a finite difference code on a set of imbricated grids derived from the Gebco 1' grid. Grids from Balearic bays (Palma for instance) are constructed after digitalization of nautical bathymetric charts, geo-referencing and krigging interpolation in order to reach a high level of details in harbours (8m resolution). Synthetic mareograms for the 1856 tsunami are then compared with witness historical data such as arrival times, wave polarity, amplitudes, etc. in order to validate the modeling and above all, the sources. Then the final inundation maps obtained from the set of scenarios should be further integrated in GIS.
DE: 4255 Numerical modeling (0545, 0560)
DE: 4562 Topographic/bathymetric interactions
DE: 4564 Tsunamis and storm surges
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 9335 Europe
SC: Seismology [S]
MN: 2007 Fall Meeting