Yasemin Korkusuz Öztürk
Bogazici University, Turkey
Title: States of local stresses and relative locations of small earthquakes in the Sea of Marmara
Biography
Biography: Yasemin Korkusuz Öztürk
Abstract
Extensional focal mechanism solutions are mostly observed in the Central Marmara by this comprehensive research although the main Marmara Fault, the western branch of the North Anatolian Fault Zone (NAFZ), is dominated by a right lateral strike-slip regime. Marmara Region is a seismically very active area. The 1912 Mürefte and 1999 Izmit earthquakes are the last devastating earthquakes of the western and eastern sections of it, respectively. The region between these earthquakes, close to Istanbul, is prone to a large earthquake. Therefore, the analysis of the Marmara Sea is significant.
The goal of this research is to determine earthquake hypocenters and focal mechanism solutions accurately, hence obtain recent states of stresses in the Marmara Region. Accordingly, this research aims to define branches of fault structures and their geometrical orientations. In this study, six clusters of earthquakes are located using hypocenter program. Next, they are submitted to the stress tensor inversion procedure and their simultaneous focal mechanism solutions are obtained. Besides, they are relocated one again using HYPODD relative location technique. Consequently, from the comparison of relocation results of hypocenter and HYPODD programs, it is found out that most of the relocations have the same orientations due to the usage of a high quality data set. Dipping angles of the segments of the Main Marmara Fault could not be observed; on the other hand, important information is discovered about seismogenic zones. Besides, mostly NE-SW oriented extensional stress structures are found in the five regions, while a right lateral strike-slip stress structure is found in the most western Marmara. Further, our sensitive relocation and stress analyses will make an important contribution to a better understanding of the fault movements of the Sea of Marmara, and shed light on earthquake rupture analyses for heterogeneous stress states and other seismological studies.