Quaternary stress regime change in the Hatay region (SE Turkey)
In this study we determine the Plio-Quaternary to present-day stress regime acting in the Hatay region located at the northeastern corner of the East Mediterranean region. The modern state of stress is obtained from inversion of focal mechanism solutions of shallow earthquakes. This inversion identifies a dominantly extensional stress regime with a NE-trending sigma(Hmin) (sigma(3) ) axis at the present-day. The stress regime determined from inversion of slip-vectors measured on fault planes confirms that this regime is extensional in the studied area. Both the kinematics and chronologies of fault slip-vectors show that the stress state changed from an earlier strike-slip regime to a younger extensional stress regime with a consistent NE-trending sigma(Hmin) (sigma(3)) axis. The change from strike-slip to extensional stress regimes probably occurred during the Quaternary. Regionally, both stress regimes induce sinistral displacement on the East Anatolian Fault and Dead Sea Fault systems. The North Anatolian Fault (NAF) is a dextral strike-slip fault which runs about 1400 km from east to west and has been active since collision between the Eurasian and Arabian plates. Together with the sinistral East Anatolian fault, the NAF intracontinental deformation zone contributes to the westward extrusion of Anatolia as a consequence of northward drift of Arabia. Consequently, the Late Cenozoic stress regimes acting in the Hatay region result from the coeval influence of forces due to: (1) the subduction processes in the west and southwest; (2) the continental collision in the east, and (3) the westward escape of the Anatolian Block. However, the timing of the temporal stress transition suggests that the Quaternary stress regime change resulted from subduction processes with the extensional stress regime in the Hatay region being mainly attributable to roll-back of the Mediterranean subducted slab along the Cyprus Arc.