Articles | Volume 12, issue 4
Nat. Hazards Earth Syst. Sci., 12, 1235–1254, 2012

Special issue: Marine and lake paleoseismology

Nat. Hazards Earth Syst. Sci., 12, 1235–1254, 2012

Research article 27 Apr 2012

Research article | 27 Apr 2012

The earthquake sedimentary record in the western part of the Sea of Marmara, Turkey

L. Drab1, A. Hubert Ferrari2, S. Schmidt3, and P. Martinez3 L. Drab et al.
  • 1CNRS/INSU, UMR8538, Laboratoire de Géologie de l'Ecole Normale Supérieure, Paris, France
  • 2Université de Liège, batiment de géographie physique, Département de Géographie, Université de Liège Allée du 6 août, 2, Bât. B11, Sart Tilman 4000, Liège, Belgique
  • 3UMR 5805 EPOC, OASU, Site de Talence, Université Bordeaux 1, Avenue des Facultés 33405, Talence Cedex, France

Abstract. 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 assessment necessitates paleoseismological data, which can be retrieved in the Marmara Sea by using sedimentary cores. Here, a record of turbidites was obtained in five cores, spanning the Tekirdağ Basin, the Western High and the Central Basin linked by the Tekirdağ fault segment. The turbidites are synchronous at different sites across the two basins and through the structural high pointing to shaking by earthquakes as a triggering mechanism. In particular, the M = 7.4 1912 Mürefte earthquake left a distinctive sedimentary imprint in all the studied cores. Radiocarbon dating implies a turbidite recurrence interval of about 300 yr. The low number of seismo-turbidites documented in the Central Basin compared to the Tekirdağ Basin suggests quasi-synchronous ruptures of the Tekirdağ Segment and the adjacent Central Segment of the NAF or a partial seismic slip on the Central Segment. Both scenarios have implications regarding seismic hazard. Finally, though we obtained a paleoseismological record of the ruptures along the Tekirdağ Segment, further chronological constraints are needed to better date the events and to confirm the completeness of the obtained record.