Seismic a and b-values and crustal parameters of Samos Island-Aegean Sea, Lesvos Island-Karaburun, Kos Island-Gökova Bay earthquakes

Authors: OYA PAMUKÇU, FİKRET DOĞRU, AYÇA ÇIRMIK, DÜZGÜN GÖNEŞ

Abstract: In recent years, seismicity has increased considerably in the Aegean Sea region and there have been earthquakes in which people lost their lives. The major earthquakes, Kos Island-Gökova Bay (Mw = 6.6), Lesvos Island-Karaburun (İzmir) (Mw = 6.2) and Samos Island-Aegean Sea (Mw = 6.9) occurred in the Aegean Sea and affected Aegean region strongly. Within the scope of this study, the seismic b-value of these major earthquakes was calculated in order to perform earthquake statistical analysis. Seismic a and b-values within the first 24 h and 14 days after the mainshock determination of Kos Island-Gökova Bay, Lesvos Island-Karaburun (İzmir) and Samos Island-Aegean Sea earthquakes were evaluated for the first time in this study. The a and b-values were found as 4.134 and 0.5924 for the Samos Island-Aegean Sea earthquake, 4.2026 and 0.8102 for the Lesvos Island-Karaburun (İzmir) earthquake, 4.6624 and 0.8446 for the Kos Island-Gökova Bay earthquake aftershocks in 24 h. The a and b-values were calculated as 4.877 and 0.7432 for the Samos Island-Aegean Sea, 4.770 and 0.8714 for the Lesvos Island-Karaburun (İzmir) earthquake, 4.9586 and 0.8711 for the Kos Island-Gökova Bay earthquake and its aftershocks in 14 days. In addition, the gravity, Moho depth, effective elastic thickness, tensor analysis and b-values were compared together for investigating the crustal features of the regions in and around the epicentres. Furthermore, the connection between the Aegean Sea and Western Anatolia was interpreted by tensors analysis. Consequently, it is found that there is a crustal problem at the lower crust of Samos Island and its surroundings, also the lower crusts of the regions including Lesvos and Kos Islands are stronger than the regions including Samos Island.

Keywords: Aegean Region, Lesvos, Samos, Kos, İzmir, earthquake, b-value, tensor analysis

Full Text: PDF