CHARACTERISTICS of SOUTH MARMARA ACTIVE FAULT SEGMENTS of the NORTH ANATOLIAN FAULT


Özalp S., Duman T. Y., Elmacı H., Kürçer A., Olgun Ş., Özdemir E., ...Daha Fazla

Turkish-German Symposium on Seismotectonic Research in the Marmara Region, İstanbul, Türkiye, 16 - 17 Ağustos 2022, ss.26-29

  • Yayın Türü: Bildiri / Özet Bildiri
  • Doi Numarası: 10.48440/afad_gfz_2022_08
  • Basıldığı Şehir: İstanbul
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.26-29
  • Akdeniz Üniversitesi Adresli: Evet

Özet

ABSTRACT The “Updating the Active Fault Map of Türkiye” study conducted by the General Directorate of Mineral Research and Exploration (MTA) was completed in 2011 and the results of the study were published in 2013. In order to reduce earthquake hazards, long and short term slip rate, earthquake recurrence interval, depth and width of the rupture zone, the maximum amount of displacement that can occur in a single earthquake, as well as the earthquake history of the active faults should be revealed. “Turkish Paleoseismology Research Project (TURKPAP)” was initiated by the MTA in 2012 within the scope of the National Earthquake Strategy and Action Plan (UDSEP-2023) in line with the aim of reducing earthquake hazards. This project aimed at investigation of the paleoseismological behaviour of the active faults in the mainland of Türkiye by utilizing the information on the “Active Fault Map of Türkiye”. This study evaluates the findings obtained by the field studies that carried out in Southern Marmara in 2013 and 2014 within the scope of TURKPAP. The importance of Southern Marmara comes from the abundance of active faults as well as the dense population and industrialization. In the study area, faults developed by strike-slip mechanism are generally accompanied by reverse and normal components. Of these, the Yenice-Gönen fault (67-km-long), which consists of six sub-segments, and the Sarıköy fault (66-km-long), which is divided into two main segments with a distinct pull-apart structure, are pure right-lateral strike-slip. Bekten fault (19-km-long), which is semi-parallel to these faults, is a transfer structure. The normal component of the Manyas fault zone (40-km-long) observed as a splay of the Yenice-Gönen fault, which is a dominant right-lateral strike-slip fault. The Pazarköy fault (42-km-long), which is divided into two sub-segments by a compressional structure, shows a similar fault character with the Yenice-Gönen Fault. The Gündoğan fault (24-km-long) is located at the eastern end of the Sarıköy fault, stepping to the right. The reverse component predominates on the Sinekçi (26-km-long), Orhaneli (30-km-long), Mustafakemalpaşa (47-km-long), Ulubat (44-km-long) and Evciler (46-kmlong) faults. Earthquakes that caused surface ruptures during the instrumental period in the research area occurred on the Yenice-Gönen fault in 1953 and Manyas fault in 1964. Paleoseismological trenches were dug on these fault segments. Earthquakes that caused surface rupture in the Quaternary period on the trench walls were determined in the light of sedimentological and structural records and supported by geochronological dating methods. It is evident that five events occurred on the Yenice-Gönen fault in the Late Pleistocene-Holocene period before 1953 earthquake, and three events occurred on the Manyas Fault Zone including the 1964 earthquake. It has been clearly observed that Sarıköy and Bekten faults caused at least three earthquakes in the Holocene period. There are geological records of two different earthquakes on Orhaneli and Mustafakemalpaşa faults through Holocene with a reverse faulting mechanism with a strike-slip component. At least three earthquakes occurred on the Ulubat and Gündoğan faults with similar mechanisms and time intervals. It has beendocumented that the Evciler, Pazarköy and Sinekçi faults are responsible of at least an earthquake caused one surface rupture in the Holocene period.

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