Recent evolution and seismogenetic structures of Hersek Peninsula (Turkey) from high-resolution seismic reflection data

Novel P- and S- wave seismic reflection datasets integrated by topographical, geomorphological, stratigraphic data provide new elements to interpret structure and evolution of a hazardous sector of the North Anatolian Fault (NAF), next to the westernmost segment activated by the 1999 earthquakes. The study area is the Hersek Peninsula, located at the southern margin of Marmara Sea. Multi-component seismic reflection data image the late glacial erosion surface unconformity and overlying sedimentary sequence. The integration with geomorphological data shows two distinct domains: a deltaic system that evolved from south to north with a progressive rotation towards west and a northern sector of the peninsula underlain by an anticline, resulting from tectonic transpression which is responsible for the uplift and tilting of the northern tip. An 8° bend of the NAF in this sector is responsible for transpression and uplifts, as validated also by numerical and analogue simulation. Such structural features match those observed in the evolution of strike-slip fault system, that evolve from large shear zone with fault stepovers, to en-echelon faults and pull-apart basins and finally to localized ruptures. Concentration of stress in single rupture zones can be used as an indicator of increasing seismic hazard.