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.
