17:45 〜 18:00
[S21-2-05] Numerical simulation of 3D mantle flow in the Aegean (Hellenic) and Cyprus subduction systems linking to seismic anisotropy beneath the eastern Mediterranean and Anatolia
Seismic anisotropy is a key parameter in understanding plate movements in relation to past/present
deformation styles, and is usually controlled by the mantle flow patterns as a consequence of dynamic
interactions between a relatively buoyant and dense subducting oceanic plate and the surrounding mantle. This study examines the evolution of splitting parameters as one of the most well established measure of seismic anisotropy and their source for the last 30Ma based on a 3D dynamic modeling performed for the eastern Mediterranean. Our model setting is chosen to be as similar to reality as possible as it consists of an active and fast moving Anatolian micro-plate, slow moving African and Arabian plates and an oceanic plate in between. The retreat of the slab in the Aegean, the alleged tear in the subducting slab close to the Cyprian trench and the break off in the slab in Eastern Anatolia are considered in our modeling study in order to see their influence on mantle flow and the splitting parameters. The synthetically calculated fast polarization directions (FPDs) mostly showed a decent matching with those inferred from previous seismological observations (SKS splitting measurements). Regions of similarities between FPDs measured from synthetic and observed shear waves mostly indicate N-S to NE-SW orientations of fast shear waves, which are parallel to the extension and in general perpendicular to the trench. Pattern of FPDs seems to be more complex near the trench. Our modeling results suggest that the development of tear in the African slab and the detachment of the Arabian plate appear to have a significant influence on the FPDs. The mantle flow through the tear close to Cyprus and the break off in the east can be identified clearly, despite their recent appearances. A circular pattern around the edges of the slab can be observed as well as disruptions of the overall general fast polarization direction due to the flow through the tear in the slab.
deformation styles, and is usually controlled by the mantle flow patterns as a consequence of dynamic
interactions between a relatively buoyant and dense subducting oceanic plate and the surrounding mantle. This study examines the evolution of splitting parameters as one of the most well established measure of seismic anisotropy and their source for the last 30Ma based on a 3D dynamic modeling performed for the eastern Mediterranean. Our model setting is chosen to be as similar to reality as possible as it consists of an active and fast moving Anatolian micro-plate, slow moving African and Arabian plates and an oceanic plate in between. The retreat of the slab in the Aegean, the alleged tear in the subducting slab close to the Cyprian trench and the break off in the slab in Eastern Anatolia are considered in our modeling study in order to see their influence on mantle flow and the splitting parameters. The synthetically calculated fast polarization directions (FPDs) mostly showed a decent matching with those inferred from previous seismological observations (SKS splitting measurements). Regions of similarities between FPDs measured from synthetic and observed shear waves mostly indicate N-S to NE-SW orientations of fast shear waves, which are parallel to the extension and in general perpendicular to the trench. Pattern of FPDs seems to be more complex near the trench. Our modeling results suggest that the development of tear in the African slab and the detachment of the Arabian plate appear to have a significant influence on the FPDs. The mantle flow through the tear close to Cyprus and the break off in the east can be identified clearly, despite their recent appearances. A circular pattern around the edges of the slab can be observed as well as disruptions of the overall general fast polarization direction due to the flow through the tear in the slab.