7-9 Sep 2022 Marseille (France)
Mass flows and other hydrodynamic consequences of small and moderate earthquakes in the Sea of Marmara
Pierre Henry  1@  , Sinan Özeren  2@  , Nurettin Yakupoğlu  3@  , Ziyadin Cakir  4  , Emmanuel De Saint-Léger  5@  , Olivier Deprez De Gésincourt  5  , Anders Tengberg  6  , Cristele Chevalier  7@  , Christos Papoutsellis  8@  , Nazmi Postacioglu  4  , Ugur Dogan  9  , Hayrullah Karabulut  10@  , Gülsen Uçarkuş  3@  , M. Namik Cagatay  3@  
1 : (b) Aix Marseille Univ, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence
Aix Marseille Université (Aix-en-Provence)
2 : Istanbul Technical University, Eurasia Institute of Earth Science
3 : Istanbul Technical University, Geological Engineering Department, EMCOL Applied Research Center, Faculty of Mines, Ayazağa, 34469 İstanbul, Turkey
4 : Istanbul Technical University
5 : INSU Division Technique de lÍNSU [Site de Brest]
Centre National de la Recherche Scientifique, Institut National des Sciences de l'Univers
6 : Aanderaa Data Instruments AS, Bergen
7 : Institut méditerranéen dócéanologie
Institut de Recherche pour le Développement : UMR_D235, Aix Marseille Université : UM110, Institut National des Sciences de l'Univers : UMR7294, Centre National de la Recherche Scientifique : UMR7294, Université de Toulon : UMR7294
8 : Institut de Recherche Dupuy de Lôme
Centre National de la Recherche Scientifique : UMR6027 / FRE3744
9 : Yildiz Technical University
10 : Boğaziçi University, Kandilli Observatory and Earthquake Research Institute
Çengelköy İstanbul 34684 -  Turquie

Earthquake-induced submarine slope destabilization is known to cause mass wasting and turbidity currents, but the hydrodynamic processes associated with these events remain poorly understood. Instrumental records are rare and this notably limits our ability to interpret marine paleoseismological sedimentary records. An instrumented frame comprising a pressure recorder and a Doppler recording current meter deployed at the seafloor in the Sea of Marmara Central Basin recorded the consequences of a MW = 5.8 earthquake occurring Sept 26, 2019 and of a Mw = 4.7 foreshock two days before. The smaller event caused sediment resuspension and weak current (< 4 cm/s) in the water column. The larger event triggered a complex response involving a debris flow and turbidity currents with variable velocities and orientations, which may result from multiple slope failures. A long delay of 10 hours is observed between the earthquake and the passing of the strongest turbidity current. The distance travelled by the sediment particles during the event is estimated to several kilometres, which could account for a local deposit on a sediment fan at the outlet of a canyon (where the instrument was located), but not for the covering of the whole basin floor. We show that after a moderate earthquake, delayed turbidity current initiation may occur, possibly by ignition of a cloud of resuspended sediment.


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