###### Abstract  
In the present work, a multiscale post-seismic relaxation mechanism, based on the existence of a distribution in relaxation time, is presented. Assuming an Arrhenius dependence of the relaxation time with uniform distributed activation energy in a mesoscopic scale, a generic logarithmic-type relaxation in a macroscopic scale results. The model was applied in the case of the strong 2015 Lefkas Mw6.5 (W. Greece) earthquake, where continuous GNSS (cGNSS) time series were recorded in a station located in the near vicinity of the epicentral area. The application of the present approach to the Lefkas event fits the observed displacements implied by a distribution of relaxation times in the range \(\tau_{min}\approx 3.5\) days to \(\tau_{max}\approx 350\) days.  
post seismic relaxation; cGNSS; hierarchically constrained dynamics; Lefkas earthquake 2021  
[PERSON], [PERSON], V.  
relaxation processes operate at different timescales [22], indicating an intrinsic organization [23] with a distribution of relaxation times, instead of the use of a single one. The latter implies that post-seismic relaxation could be viewed as the superposition of several different relaxation times, each one activated in different mesoscopic domains of the macroscopic relaxed seismic volume. Thus, the macroscopic relaxation observed results from the superposition of different relaxation times on the microscopic-mesoscopic scale, which obviously operates on different spatiotemporal scales. The recovery process that returns the deformed volume to equilibrium after a strong earthquake could be characterized as a slow dynamics process [24], because an instantaneous perturbation causes a transient response, which moves the system to a state of equilibrium [25; 26; 27; 28; 29; 30]. It is, thus, possible that relaxation, which varies with the logarithm of time, can be interpreted as the result of the superposition of relaxation mechanisms with a spectrum of relaxation times.  
The purpose of this work is to give a description of the post seismic deformation relaxation. It is based on the thermodynamic Arrhenius model for the distribution of the relaxation times [31] and describes the post-seismic recovery as a slow thermodynamic process taking place in a mesoscopic scale. The model predicts a physically accepted finite value just after the co-seismic perturbation, a logarithmic time dependence for the time period between the minimum and maximum relaxation time, and an exponential decay while approaching an equilibrium state a long time after the main event. Based on that, the explanation that relaxation occurs as a logarithm of time does not depend on the details of Earth's physical and chemical properties, but is based on a generic, or even a universal, multiscale property of the relaxation mechanism, as resulted from the Arrhenius expression, which connects relaxation time with the activation energy of the relaxation process.  
To test the proposed approach for the post-seismic relaxation, positioning data from the continuous GNSS station PONT [32] and www.geodesy.gein.noa.gr (accessed on 30 December 2020) located in the southern part of Lefkas Island were used. This cGNSS station is located in the close vicinity of the earthquake epicenter of the 17 November 2015 Mw6.5, shallow event (\(\sim\)10 km depth), that occurred on the island, causing severe damages and human losses.