Bat Anadolu’nun en bat ucundaki güncel yaplardan biri olan zmir Körfezi; KD, KB, K-G ve D-B uzanml faylar tarafndan denetlenen denizel bir havzadr. Körfezin güney kenar üzerindeki KonakGüzelbahçe bölümü zmir Fay ile snrlandrlmtr. zmir Fay bu kesimde yaklak D-B uzanml birbirine paralel iki ana segmentten yapldr ve Balçova’dan Güzelbahçe’ye kadar 1/25.000 ölçeinde haritalanmtr. Arazi verilerine göre zmir Fay kuzeye eimli ve oblik atm bileenli normal fay niteliindedir. Körfezin kuzey kenar üzerindeki Bayrakl-Karyaka bölümü, zmir Fay’nn antitetii olan Karyaka Fay ile snrldr. Karyaka Fay bu kesimde yaklak D-B uzanml ve güneye eimli oblik atml normal fay niteliindedir. zmir Fay’na yaklak dik gelien ve Sack Körfezi’nden Seferihisar ve Yelki-Güzelbahçe ilçesine kadar haritalanabilen Seferihisar Fay, Urla Havzasnn dou kenarn oluturur. Seferihar Fay’nn Sack Körfezi ile Yelki köyü arasndaki bölümü K20OD uzanml sa yönlü dorultu atml bir fay zonu eklindedir. Fayn Yelki-Güzelbahçe arasndaki 5 km uzunluundaki kesimi K50OD dorultusunda uzanr ve Güzelbahçe’den itibaren kuzeydouya doru zmir Fay’na deiir. Bu zonda 1/1000 ölçeinde haritalanan fay segmentleri üzerinde açlan hendeklerde, dorultu atml fayn (Seferihar Fay) bükülerek normal faya (zmir Fay) dönütüü saptanmtr. 

İzmir Bay, one of the recent structures of Westen Anatolia, is a marine basin controlled by NE, NW, N-S and E-W trending active faults. The southern sector of the bay is bounded by the zmir Fault, lying between Konak and Güzelbahçe village. The zmir Fault in this section is made up of two main segments trending approximately in an E-W direction, and is mapped on a 1/25000 scale from Balçova to Güzelbahçe Village. According to field studies, the zmir Fault is an oblique-slip normal fault dipping to the north. The northern sector of the bay between Bayrakl and Karyaka districts is bounded by the Karyaka Fault, which is antithetic to the zmir Fault. In this section, the Karyaka Fault is characterised by an oblique-slip normal fault dipping to the North. The Seferihisar Fault, which is approximately developed and normal to the zmir Fault, and has been mapped from Sack Bay to Güzelbahçe-Yelki district, forms the eastern margin of the Urla basin. The segment of the Seferihisar Fault that lies between Sack Bay and Yelki Village is in the form of a N20E trending right-lateral strike-slip fault. The 5 km length of the fault segment lying between Yelki and Güzelbahçe trends in a N50E direction and, beginning from Güzelbahçe village, is transformed into the zmir Fault toward the northeast. Within the excavated trenches on the fault segments mapped on a 1/1000 scale, it is established that the strike-slip fault (Seferihisar Fault) is transformed by bending into the normal fault (the zmir Fault). Kinematic analysis carried out at 9 stations suggest that the paleostress forming the faults has controlled under an approximately NS extensional direction associated with an EW contraction. The data support that the kinematically linked zmir Fault, Seferihisar Fault and Karyaka Fault contributed to the opening of zmir Bay as a response to the transtensional forces.