Plate-Scale Seismic Studies of Anatolia: Implications on Tectonic Interpretations
IPGP - Îlot Cuvier
Séminaires de Sismologie
Istanbul Technical University (ITU)
Dense coverage of high-quality seismic data combined with modern modeling and tomography techniques are in the process reshaping and refining our understanding of Anatolian tectonics. Recently conducted receiver function analyses and multiscale full waveform inversion, in particular, provide new information on the interaction between upper-mantle dynamics and near-surface processes and observations. Receiver functions covering the wider Anatolian region reveal a sharp drop in Moho depth across the East Anatolian Fault, suggesting that the fault demarks the boundary between the Anatolian and Arabian plates. Moho depths beneath the East Anatolian Plateau are 40-55 km with the deepest measurements to the North and Northeast. These signals are consistent with observed high topography of around 2 km being supported by mantle forces or slab break-off models rather than crustal thickening. In addition to the Moho depths, the shear wave velocity crustal structure is independently determined from Bayesian inversion of receiver functions. Results underline the complex nature of Anatolian crust. Full waveform inversion of complete broadband seismograms constrains the crustal and upper-mantle signature of the North Anatolian Fault Zone. The fault zone is bound by high-velocity blocks within the crust suggesting that it developed along the edges of continental fragments with high rigidity. Below the crust, the surface expression of the North Anatolian Fault Zone correlates with a 600 km long low-velocity band. This is interpreted as the upper-mantle expression of Tethyan sutures that formed 60–15 Ma ago. The structurally weak suture facilitated the formation of the younger crustal fault zone.