Modelling tectonic deformation along the North-Anatolian Fault in the Sea of Marmara

Abstract

Using analogue techniques, we attempted to model the complex tectonic deformation pattern observed along the North-Anatolian Fault in the Sea of Marmara from morpho-bathymetry and seismic reflection images. In particular this paper focuses on the so-called Cinarcik segment of the fault connecting the eastern Izmit segment, which entirely ruptured during the Mw 7.4, 1999 earthquake, to the western segment of the Central High. The Çınarcık segment, potentially loaded after the Izmit earthquake, is expected to rupture during an earthquake occurring in the near future, possibly the next decades, with a high potential to affect the Istanbul metropolitan area. Our analysis suggests that the development of the observed structures accommodating strike-slip, transtensional and transpressional deformations, could be explained by changes in the geometry of fault segments within a right-lateral strike-slip tectonic regime. Tectonic deformations were reproduced in the analogue model by imposing a small (about 10°) and sharp difference in the relative orientations of the strike-slip segments at the edges of a major releasing bend. In the model slower strain accumulation occurs along the analogue of the Çınarcık segment than along the analogue of the Izmit segment of the fault. This would predict a delay for earthquakes triggered by stress transfer between the Izmit and Çınarcık segments. The model further predicts that most of the deformation in the Çınarcık basin is controlled by the sharp changes in the geometry of the fault itself.

Active fault segments along the North Anatolian Fault system in the Sea of Marmara: implication for seismic hazard

“…This deformation zone is characterized by partitioning over various fault branches at the plate boundary and contributes to the formation of compressional or extensional structures in correspondence of restraining and releasing bends, respectively. This behavior should also be controlled by changes in fault geometries and block rotations, as also suggested by analog modelling in the Sea of Marmara (Bulkan et al 2020).…”

Tsunami potential source in the eastern Sea of Marmara (NW Turkey), along the North Anatolian Fault system

“…Consequently, the northern edges of these basins are formed by NW-SE oriented normal faults connecting the shelves with the deep depocenters, reaching a dip of 25-27°. Small changes in the Eurasia-Anatolia relative motion vectors have produced complex transtensional and transpressional deformations along the main fault segments, constituting weak "spots" of deformed terrains affected by gravitative instability (Bulkan et al 2020).…”

A review of last interglacial sea-level proxies in the eastern Mediterranean coastal region

“…The northern NAF strand creates deep tectonic depressions separated by structural highs (Jenkins et al, 2020). High rates of NAF motion (~20 mm/a) progressively increasing westward (Bulkan et al, 2020) and associated earthquakes makes the area a prime subject of hazard studies. Studying Pleistocene marine terraces in this area aims therefore at determining uplift rates and, in addition, the hydrodynamic history between the Black Sea and the Aegean Sea.…”