The Role of Co-Seismic Devolatilization in Driving Aftershock Sequences in Greece

We investigate the role of co-seismic devolatilization in driving aftershock sequences, focusing on three recent sequences in Greece: Thiva, Damasi, and Florina. We use a numerical model incorporating non-linear diffusion with a source term that accounts for fluid generation via thermal decomposition of carbonates. Our model successfully reproduces the spatio-temporal characteristics of the observed aftershock sequences, with especially strong correlations between observed and modeled aftershock rates. The calibration of the model, which introduces key parameters for fluid generation and permeability recovery, provides new insights into the mechanisms of aftershock generation. It reveals a consistent magnitude threshold above which a significant amount of fluid is produced. The fluid pressure generated remains within the same order of magnitude regardless of the earthquake size. Our results suggest that co-seismic fluid generation, either through decarbonation or dehydration reactions, is a significant driver of aftershock activity in these regions, and likely globally. These findings highlight the importance of incorporating fluid-related, and fluid-generating, processes into models of seismicity, especially in tectonic environments where devolatilization is likely to occur.