Unit:
Κατεύθυνση ΣεισμολογίαLibrary of the School of Science
Author:
Fountoulakis Ioannis
Supervisors info:
George Kaviris, Assistant Professor (National and Kapodistrian University of Athens)
Panayotis Papadimitriou , Professor (National and Kapodistrian University of Athens)
George Drakatos, Research Director (National Observatory of Athens)
Original Title:
Crustal and upper mantle structure of the broader Greek region using receiver functions and seismic anisotropy
Translated title:
Crustal and upper mantle structure of the broader Greek region using receiver functions and seismic anisotropy
Summary:
Greece is one of the most geodynamical interesting regions worldwide, with a plethora of available geological features. The present study aims to examine parts of these geodynamical features using the Shear-Wave Splitting phenomenon and the Receiver Functions methodology.
SKS and PKS splitting parameters were determined in the broader Greek region using data from 45 stations belonging to the Hellenic Unified Seismological Network and the Kandilli Observatory and Earthquake Research Institute Network, utilizing teleseismic events that occurred between 2010 and 2017. The shear-wave splitting parameters have been determined using the Minimum Energy Method that was considered the optimal, within the SplitLab software. In general, the obtained results confirm the existence of anisotropic zonation in the Hellenic subduction system, with alternating trench normal and parallel directions. The zonation is interpreted with the existence of upper and lower olivine fabric layering in the subduction zone. Two possible cases of toroidal flow have been identified at the edges of the subduction zone, implying the existence of tears that allow the inflow of asthenospheric material in the mantle wedge. High number of “Null” measurements determined in the KZN and XOR stations indicate a possible anisotropic transition zone between the fore-arc and back-arc areas. SKS and PKS splitting measurements are jointly interpreted, given that they yield similar results in most cases.
Receiver Functions technique was applied in 49 stations of the Hellenic Unified Seismological Network using the same teleseismic events catalogue (2010 - 2017). Iterative and Waterlevel deconvolution was applied in order to remove the source effects from the teleseismic signal. The H-k stacking method was utilized for the Moho depths determination. Iterative deconvolution yielded more reliable results, but the methods were jointly interpreted. The results confirm the existence of a thick crust beneath the Hellenides which is decreasing gradually in the Aegean Sea. Negative Ps conversions were observed locally in the vicinity of the subduction area, especially in the Crete island, sign of possible serpetinization. In addition, the determined from the H-k stacking high
Vp/Vs ratios in western Greece indicate partial melting in the broader region.
Main subject category:
Science
Keywords:
Seismic anisotropy, SKS, Receiver functions, Moho depths, Earth's interior, Greek region
Number of references:
200
