Source characteristics of earthquake along the western Hellenic arc

Περίληψη

In the present study, an effort is made to investigate the seismic source parameters of the Western Hellenic arc, processing seismograms from earthquakes generated in the particular area the last decade. Six were the largest events that struck during this period of time: the first (M w =6.0) occurred on March 17, 2004 at 35 km depth, south of the Island of Crete, the second one (M w =6.6) on January 8, 2006 at 70 km. On February 2008 three strong earthquakes ruptured 30 km of the western Hellenic Trench, south of Peloponnese, the February 14, 2008 M w =6.6, the February 14, 2008 M w =6.0 and the February 20, 2008 M w =5.9 events. The most recent earthquake (M w =6.6) occurred on October 13, 2013 at a depth of 40 km, west of the Island of Crete. All seismograms were processed with the teleseismic bodywave inversion program developed by Kikuchi and Kanamori (2003). The study starts with a brief, introductory reference to the general seismotectonic framework of Greece, the crustal movements and seismicity observed, focusing in particular on the seismotectonics of the under study region, the Wadatti-Benioff zone and previous studies in the area. In the second chapter, the theoretical background of focal mechanism, seismic moment tensor inversion and spectral analysis is given. The following chapter refers to the application of teleseismic bodywave inversion method to the selected earthquakes. Fault plane constraints are employed for all events and the final source time function is determined, along with the fault plane solution. The fourth chapter presents the spectral analysis for two of the earthquakes, the January 8, 2006 M w =6.6 Kythera  earthquake and the October 12, 2013 M w =6.5 W Crete earthquake. The first event was chosen because it is the greatest in magnitude that is studied here and the second event because of its recent occurrence and the fact that it has not been fully examined yet. Finally, the last  chapter presents a discussion over interesting findings and drawbacks during the elaboration of the study and then briefly concludes with final parameters obtained for every earthquake, comparing them to the known seismotectonic regime of the under study area. At the end of the present study, references and supplementary material are cited. The last comprises data processing and additional teleseismic station tables that were excluded from the main part of the study.