Temporal variations of b-values in central Ionian Islands (Greece)

摘要

Investigation of temporal b-values variations during the last decade is attempted in central Ionian Islands (Greece), the most seismically active area in the Mediterranean area. The high quality catalogue used, starting in 2008 with the completeness magnitude M-c 2.8 comprises data from the aftershock sequences of the 2014 Cephalonia doublet (M-w 6.1 and M-w 6.0) and the 2015 Leukas M-w 6.5 mainshock along with periods of relative quiescence. The analysis is performed by means of two alternative techniques, the "fixed - number - of - events" and the "constant - time - windows" approaches. The results indicate that b-value variations are inversely proportional to the seismicity rate with the decreases representing high seismic moment release. For a more detailed monitoring of the fluctuation of b-values in time and space, the competently elaborated 2015 Leukas sequence is employed. The results indicate that during the sequence, immediately after the occurrence of the mainshock and for about a month, a decrease in b-value is observed, which gradually increases towards the background value.