Morphological Features of Major Submarine Landslides of Marmara Sea Using Multibeam Data

Recent bathymetric surveys help us to understand morphological features of the Marmara Sea. Marmara Sea has unique and complex morphological features and active tectonics. In this study, morphologic features of major submarine landslides of the Marmara Sea were studied using advanced visualization and geomatic systems (digital terrain models, DTM; geographic-information systems, GIS; image-processing systems; high-resolution seismic and bathymetric data). The high-angle continental slopes of the Marmara Sea are produced by submarine landslides and slumps, which have potential tsunamis generations. In this study, tectonically active major submarine landslides were investigated in the Marmara Sea. Three of them are observed along the slopes, one is on the Eastern Ridge and the fifth forms the Western Ridge of the Marmara Sea. They are interpreted as rotational and translational slides, debris flows, and mudflows controlled by slope and tectonic activity. On the northern slope of Çınarcık Basin, rotational slide and debris flows, which are activated by faults, affect the current shape of this slope. Hence, we interpret that the present morphology of the slopes of the Marmara Sea may not be only controlled by faults but also the landslides. On the other hand, mudflows in Tekirdağ Basin and in the Marmara Sea entrance of Izmit Bay (Çınarcık Basin) may be controlled by slope inclination and sediment supply rather than tectonics. Another mudflow on the Eastern Ridge initiated by the inclination of the ridge by a reverse fault in the northwest side of the ridge, thus, slope inclination controlled by tectonic activity affects the origination of this landslide. One of the largest landslides in the Marmara Sea forms the Western Ridge as a translational slide. Its initial shape has been destroyed by the new rupture of the North Anatolian Fault Zone, thus, it may be one of the oldest submarine landslides of the Marmara Sea.