T13B-2996
Structural analysis of the southwestern segment of the Hellenic subduction zone by joint analysis of seismic reflection and refraction

Monday, 14 December 2015
Poster Hall (Moscone South)
Clement Vitard1, Philippe Charvis1, Mireille Laigle1, Maria Sachpazi2, Audrey Galve3, Laure Schenini1, Anke Dannowski4 and Bellas Spyridon5, (1)GeoAzur, Valbonne, France, (2)National Observatory of Athens, Athens, Greece, (3)UMPC, UNSA, CNRS, IRD, Géoazur,, Valbonne, France, (4)GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany, (5)Hydrocarbons W/G Ministry of Reconstruction of Production, Environment & Energy General Secretariat for Energy & Raw Minerals General Directorate for Energy Hydrocarbons Directorate, Athens, Greece
Abstract:
The Hellenic subduction zone is characterized by the highest rate of current seismicity in Europe. In the southwestern segment, several earthquakes of large magnitude (Mw 7.5-8) occurred at the turn of the 19th to 20thcentury. This segment has also been the nucleation site of the largest historical earthquake in Europe, the 365 AD earthquake, with a magnitude of Mw 8. This event generates a devastating tsunami, which spread along the Adriatic Sea and in the Nile Delta region.

The southwestern segment of the Hellenic subduction zone has been the aim of a marine geophysical survey on board the N/O Le Pourquoi Pas? of IFREMER, in November 2012. During this survey, two seismic refraction profiles perpendicular of the subduction have been carried out. These two profiles of 25 OBS/OBH each are coincident with two other seismic reflection profiles by using a 11000 cu.inch airgun source. An additional set of 650 km of seismic reflection profiles has been acquired. The aim of this study is to image the megathrust fault in the depth range of 15 to 40 km, identify the structural markers of the downdip and updip limits of the potential seismogenic zone and the geometry variation of these markers along this segment.

During this survey, Chirp and multi-beam bathymetric data have also been collected. These elements provide constraints on the superficial and recent tectonic evolution in the region.

In this study, we will propose an interpretation of all the imaged structural markers, in the overriding plate and in the subducted plate, of the first meters down to 40 km depth, with the analysis and the comparison between the two main profiles of seismic reflection on the one hand and one refraction profile on the other hand.

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