Abstract
We have been studying some seismicity characteristics in the regions of the eastern Aegean Sea and Western Turkey. We used a method based on identification of ring-shaped seismicity structures. It was established that shallow (h=0–33 km) ring-shaped structures with threshold magnitude values of Mt in the range of 3,8–4,5 have been formed during a few decades prior to five large earthquakes (Mw=6,4–7,6) that occurred in 1995–2017. The sizes of these structures were a few times less than for intracontinental earthquakes with mechanisms of strike-slip and normal faulting types that have corresponding magnitudes. Besides that, deep (h=34–70 km) seismicity strips were identified there. It was shown that epicenters of large earthquakes are often located near areas of crossing or the closest rapprochement of shallow rings and deep strips. Shallow ring-shaped structure (Mt=4,3) was identified in the area of the sea of Marmara, where no eventswith Мw≥7,0 occurred at least since 1900. Moreover, deep seismicity strips also were displayed here. We estimated magnitude of the large event, which can prepare in the area of the ring-shaped structure. The estimate is based on earlier obtained correlation dependences of seismicity ring parameters on energy of main earthquakes with mechanisms of strike-slip type: Mw=7,3±0,1. The formation of ring-shaped structures and deep seismicity strips is supposed to be connected with processes of geological systems self-organization, which result in deep-seated fluids migration.
Published Version
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