[en] The submarine part of the North Anatolian Fault (NAF) is a very significant hazard for the 12 million people living in Istanbul (Turkey). An accurate seismic risk assess- ment necessitates paleoseismological data, which can be re- trieved in the Sea of Marmara only using sedimentary cores. Here a record of turbidites was obtained in five cores span- ning the Tekirdag ̆ Basin, the Western High and the Central Basin linked by the Tekirdag ̆ Fault Segment. The turbidites are synchronous at different sites across basins and structural highs. The only possible triggering mechanism is thus shak- ing related to major earthquakes. In particular the M=7.4 1912 Mu ̈refte earthquake has let a distinctive sedimentary imprint in all the studied cores. Radiocarbon dating implies a turbidite recurrence interval of about 300 years. In addi- tion the low number of turbidites documented in the Central Basinsuggestsquasi-synchronousrupturesoftheTekirdag ̆ Segment and the adjacent Central Segment of the NAF or a partial seismic slip on the Central Segment. Both scenarii have implications regarding seismic hazard. Finally through we obtained a reliable paleoseismological record of the rup- tures along the Tekirdag ̆ Segment, further chronological con- straints are needed to accurately date the events and correlate them with known historical earthquakes.
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS