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Temporal and spatial variations in the Sea of Marmara based on monthly averages of chlorophyll a, which is the major indicator of phytoplankton biomass and primary production, recorded by SeaWiFS and MODIS-Aqua sensors at nearly 100 stations have been analyzed for the period of 1997-2007. Majority of phytoplankton blooms occur during the winter and spring seasons, followed by a smaller secondary bloom during the fall season. The majority of high magnitude blooms occur at the Eastern part of the Sea which may be attributed to an increase in the amount of discharge of water contaminated with nutrients originating on land where the industries are located. The correlations between monthly averages of sea surface temperature (SST) and corresponding chlorophyll a values are statistically significant (inverse) at 1% level, where r= -0.53 and the equation of the fitted model is: Chlorophyll a = 7.09199 &ndash / 0.215402* SST This correlation is expected because a relative decrease in SST is an indicative of upwelling and vertical mixing which are the primary processes for the formation of phytoplankton blooms. We have also found that monthly averages of chlorophyll a recorded by SeaWiFS and MODIS-Aqua are nearly identical and either data set can be used in place of the other.

In this thesis study / mechanism and modeling of tsunamis generated by landslides are investigated. Landslide parameters affecting the surface wave characterisics are studied. In order to understand occurance of this kind of tsunamis, among many historical tsunamis, the ones that are triggered by landslides are detected and studied. The generation of the landslide generated tsunamis are modeled using TWO-LAYER model, which solves nonlinear long wave equations simultaneously within two interfacing layers with necessary boundary conditions at the sea bed, interface and water surface. The model is applied to one of the possible landslides at offshore Yalova in the Sea of Marmara. Two of the controlling parameters, which are the density and the thickness of the slid material, are analysed and a sensitivity analysis is performed to determine the level of their effects on the evolution and amplitude of the tsunami source. Furthermore, the propagation and coastal amplification of the landslide generated waves are investigated using the tsunami simulation and visualization code NAMI DANCE. The results are presented, compared and discussed.

Cette thèse porte sur la déformation et les migrations de fluides associées à la Faille Nord Anatolienne en Mer de Marmara (Turquie).Nous étudions tout d'abord l'évolution de la géométrie et du taux de glissement du système de faille, par deux approches indépendantes: - modélisation thermique de l'histoire d'un bassin, - définition d'un marqueur temporel de type Dépôt de Transport en Masse, daté par interprétation stratigraphique. Nous montrons que: -(1) le système de failles actuel, défini comme une faille principale accommodant la majorité de la déformation inter-plaque, n'a pas significativement évolué depuis 330.000 ± 100.000 ans dans la partie Ouest de la mer; -(2) le système de faille s'est progressivement réorganisé depuis 2.5-1.5 Ma.Dans un deuxième temps, nous étudions les processus d'initiation des Transports en Masse. Nous montrons que: -(1) même si les Transports en Masse sont contrôlés par des processus tectoniques (principalement les séismes et l'extension crustale), leur fréquence et leur taille sont conditionnées par les oscillations glacio-eustatiques; -(2) des Dépôts en Masse ont une périodicité corrélée aux transitions marins/lacustres. Cette cyclicité peut être expliquée par la diffusion d'eau saumâtre, dans les argiles marines entraînant leur gonflement et déstabilisant les sédiments. Dans une troisième partie, nous étudions la diversité des contextes des sites d'émissions de fluides en fonds de mer. Nous montrons que l'occurrence des sites d'émission de fluides est en partie liée au flux ascendant de gaz le long de couches perméables des bassins vers leurs bords, et le long des fractures du socle vers les bords des bassins et les anticlinaux. / This study addresses the issue on the deformation and the fluid migration, associated to the North Anatolian Fault within the Sea of Marmara (Turkey).First, we aim to constrain the evolution of the fault network and the slip rate through time, by two independent approaches: - historical thermal modeling of a basin of the Sea of Marmara; - definition of a Mass Transport Deposit as a fault lateral slip marker, and dated by stratigraphic interpretation. We show that: - (1) the present day fault system, formed by a main fault which accommodated the main part of the inter-plate deformation does not significantly evolved since 330.000 ± 100.000 years - (2) a progressive reorganization of the fault network occurred since the last 2.5-1.5 Ma.Secondly, we discuss the triggers of Mass Transport Processes. We show that: - (1) despite submarine mass movements are related to tectonic activity (mainly earthquakes and crustal stretching), their frequency and their size are also modulated by glacio-eustatic changes; -(2) remarkable Mass Transport Deposits display some cyclicity in stratigraphic sequences which are apparently correlated to transitions between salty marine and lacustrine environments. This cyclicity is perhaps explained by marine clay activity (swelling) under low brackish-fresh water conditions, which can trigger sediment destabilization.Third, we investigate the diversity of active fluid seepages contexts. We propose that the widespread occurrence of fluid expulsion sites can be explained by up-dip gas migration by buoyancy along permeable strata toward their edges, and along fractures within the basement toward both the edges of the basins and topographic highs.