First evidence of the non-extensive character of pre- and post-seismic deformation of Samos (2020) Mw7.0 earthquake

The statistical patterns occurring on the threshold of an earthquake, in the transition stage immediately before and after the rupture, still remain unclear. Investigating the dynamical features of surface deformation a few days before and after the earthquake co-seismic rupture are crucial to understand the mechanics of the earthquake process. In the present work, we study surface displacements as estimated using continuous GNSS measurements in the vicinity of the 2020 Mw7.0 Samos (Greece) strong, shallow earthquake. The GNSS time series before and after the Mw7.0 earthquake in SAMO (belonging to METRICA SA HexagonSmartNet commercial network) station demonstrate significant surface deformation in the broader epicentral area. We further analyze the surface displacement increments a few days before and after the Samos Mw7.0 earthquake using the non-extensive statistical physics (NESP) framework, which could provide a frame to study the complexity of the earthquake process. The results of the analysis suggest that the statistical distribution of ground displacement increments presents asymptotic power-law behavior that deviates from the standard Gaussian function. Instead, the observed distributions can be described by the q-Gaussian function derived in the NESP framework, for q-values in the range of 1.10–1.15. In addition, the statistical pattern that was obtained from the analysis is further discussed in terms of superstatistics, indicating that the ground displacement increments a few days before and after the Mw7.0 earthquake correspond to a system with high enough degrees of freedom of the order of 13–15. Furthermore, for comparison, a four years record of continuous GNSS measurements was analyzed using NESP. The results support the non-extensive character of displacement increments using a four years period of recordings suggesting long-range temporal correlations.