Accelerating seismic crustal deformation before strong mainshocks in Adriatic and its importance for earthquake prediction

Time accelerating Benioff strain release before the mainshock has been observed in all five cases of strong (M>6.0) shallow mainshocks, which have occurred during the last four decades in the area surrounding the Adriatic Sea. This observation supports the idea that strong mainshocks are preceded by accelerating seismic crustal deformation due to the generation of intermediate magnitude shocks (preshocks). It is further shown that the values of parameters calculated from these data follow appropriately modified relations, which have previously been proposed as additional constraints to the critical earthquake model and to the corresponding method of intermediate term earthquake prediction. Thus, these results show that the identification of regions where time-accelerating Benioff strain follows such constraints may lead to useful information concerning the epicenter, magnitude and origin time of oncoming strong mainshocks in this area. The procedure for identification of the time-acceleration is validated by appropriate application on synthetic but realistic random catalogues. Larger dimension of critical regions in Adriatic compared to such regions in the Aegean is attributed to an order of magnitude smaller seismic deformation of the crust in the former in comparison to the latter.