Thermal and rheological characteristics of the Main Marmara Fault - a segment of the North Anatolian Fault - and its surrounding regions in the Eastern Mediterranean

The Main Marmara Fault - a segment of the active North Anatolian Fault Zone - poses significant seismic hazard to the metropolitan area of Istanbul, where a potentially hazardous earthquake of M>7 is overdue.  This part of the larger strike slip system extends across the northern Sea of Marmara and exhibits a still poorly understood segmentation along‐strike, with creeping and locked parts.  Continuous research in the recent years using data collected in the GONAF observatory initiated by the ICDP and results obtained in the frame of the DFG-ICDP priority program enabled the construction of a new 3D lithospheric‐scale model of the Sea of Marmara. We combined gravity modelling and seismic tomography analysis with thermal and rheological modelling to derive the crustal density structure to gain insights into the temperature and density configuration of the uppermost mantle, and the geometry of the 1330°C isotherm. We find a lower‐density crust over the western and creeping part of the Main Marmara Fault, and a denser crust below the locked part of the Main Marmara Fault at the Istanbul Zone and analyse and discuss the implications of these structural heterogeneities.