Active tectonics of Gülpınar-Tuzla area (Biga Peninsula, NW Turkey): The source of 6 February-24 March 2017 earthquake cluster

The variation in the motion sense of Anatolian platelet Aegean Sea resulted a strike-slip tectonic regime and related neotectonic domain, central to northern province, which also includes both western Marmara Biga Peninsula. Our study focuses mostly on Gülpınar-Tuzla earthquake area located at southwestern tip Peninsula, is controlled by southern major strand North Fault System (NAFS). consists two sections, onshore offshore Babakale-Skyros sections. Both sections are seismically very active. composed Paleozoic metamorphic rocks, Oligo-Miocene granitoid pluton, Lower-Middle Miocene calc-alkalic volcanic rocks Upper Miocene-Pliocene sedimentary sequence. All these formed deformed (folded tilted) palaeotectonic period, overlain with an angular unconformity Quaternary basin fill, that nearly flat-lying except for faulted margins. linked each other terms structures characterizing Babakale pull-apart area. latter shaped NE-trending Gülpınar (GFZ) Yenice-Gönen Zone (YGFZ), ENE-trending Edremit fault zone (EFZ), WNW-trending Tuzla (TFZ) three basins (Ayvacık, Behramkale basins) developed along them. Some segments TFZ GFZ were reactivated occurrences seven moderate-to small-sized independent earthquakes aftershocks over 2760. Five have origin oblique-slip normal faulting, while rest seismic events faulting origin. Focal mechanism solution diagrams groups reveal under control regime, commenced Early time owing inversion extensional regime. This supported palaeostress analysis slip-plane data measured slickensides. uniform slip rates YGFZ EFZ 10.8 mm/yr 7.3 mm/yr, respectively.