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Devrim Başar Han | Dec 24, 2024
The North Anatolian Fault Zone (NAFZ), is a tectonic structure that's really important because of the active deformation it causes in Türkiye. If we can understand how the directional dependence of seismic waves also known seismic anisotropy in the crust and mantle along this nascent shear deformation zone works, we can learn a lot about the kinematics of past and present tectonic events. Research Assistant Derya Keleş, Assoc. Prof. Dr. Tuna Eken, and Prof. Dr. Tuncay Taymaz from the Department of Geophysical Engineering could map seismic anisotropy variation in an area covering northwest segment of the NAFZ.
Research Assistant Derya Keleş, Assoc. Prof. Dr. Tuna Eken, and Prof. Dr. Tuncay Taymaz have analysed teleseismic observations of distant earthquakes to understand past and present geodynamic events that have shaped the crust and upper mantle structure beneath the NAFZ and its vicinity. Seismological methods used in that study revealed detailed patterns of crustal and mantle kinematics, providing insights into how the Earth's layers have been deformed. Research team has found that faults in the region respond to earthquakes and are concentrated in the brittle part of the crust. The distinct patterns beneath the north of the NAFZ imply the presence of a distinct lithospheric domain, particularly associated with the Odessa Shelf in the lower crust and upper mantle.
The crustal deformation caused by the NAFZ demonstrates how strain accumulates during earthquake cycles, leading to the formation of faults in the crust. The study region's seismic anisotropy variations, both lateral and vertical, provide crucial insights into the geological processes shaping the Earth's structure in this area.
Source: Keleş, D., Eken, T., Licciardi, A., Frederiksen, A. W., & Taymaz, T. (2024). Depth‐dependent anisotropy along northwest segment of the North Anatolian Fault Zone: Evidence for paleo‐tectonic structures contributing to overall complexity. Journal of Geophysical Research: Solid Earth, 129, e2023JB028014. https://doi.org/10.1029/2023JB028014
You can reach the paper by following links:
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023JB028014
Figure: This cartoon illustration taken from Keles et al. (2024) shows the sketch model inferred from our receiver function modelling and SKS splitting measurements for the study area. The black solid lines on the map represent active major faults that also separate three tectonic zones, namely, Istanbul Zone, Armutlu-Almacık Block, and Sakarya Zone in the region. On the right side, the angular representation corresponds to the horizontal axis of symmetry, and its plunge angle representing actual orientation of seismic anisotropy.