Abstract
Pliny-Strabo Trench (PST)is a Subduction Transform Edge Propagator (STEP) fault developed at the northern edge of the African oceanic lithosphere connecting the Aegean and Cyprian trenches in the eastern Mediterra-nean. Recent studies have demonstrated that the PST terminates close to Turkish Border and links to the Cyprian trench east of Rhodes and south of Fethiye-Gocek Bay. However, it is also claimed that the PST extends into SW Anatolia along a sinistral transtensional shear zone, so-called Fethiye-Burdur Fault Zone (FBFZ) implying that a lithospheric tear in the downgoing plate extends into the over-riding plate, although, this is kinematically almost impossible since full mechanical coupling between down going and the over-riding plate is necessary. To test this hypothesis and understand the kinematics of the transition zone between PST and Cyprian trench we have conducted a rigorous paleostress inversion study combined with interpretation of 2D seismic data of which 228 km total length obtained from Fethiye-Gocek Bay.
The seismic reflection data are used for the interpretation and delineation of off-shore faults and to determine their recent activity. The geometry and kinematics of the exposed on-land faults are determined by analyzing 13969 fault slip data obtained from 211 sites distributed evenly throughout in an area encompassing the bay in an area extending 70 km in E-W and 50 km in N-S that cover the whole area where the Pliny-Strabo STEP fault would emerge on-land. Results of analyses indicated that most of the faults in the study area are developed under multi-directional extension, except for some NE-SW-striking faults, which have dextral strike-slip components contrary to pro-posed sinistral nature of Fethiye-Burdur Fault Zone. Although there are numerous normal faults some which have been active until recently, however, there is almost no NE-SW striking sinistral strike-slip fault in the region to justify the presence of Fethiye-Burdur Shear Zone. Additionally, there are a number of earthquakes with dominantly strike-slip moment tensor solutions in the deeper part of the bay while they are in normal character in the on-shore areas suggesting that the Pliny-Strabo Trench stops very close to the shoreline and it does not propagate into SW Anatolia. Therefore, existence and alleged characteristics of the Fethiye-Burdur Fault Zone could not be verified.