<p>Understanding deformation mechanisms throughout the seismic cycle, particularly the modelling of post-seismic deformation, remains a challenging and actively debated topic. Analysing seismic loading processes is essential because it provides critical constraints for improving earthquake hazard assessment. Strong earthquakes systematically induce crustal deformation at the surface, with effects lasting from weeks to decades, extending over large areas. Radar sensors onboard Earth observation satellites are widely used to measure ground deformation. In recent years, multi-temporal InSAR (MTI) methods have emerged as powerful tools for monitoring surface deformation. However, MTI-derived results are often affected by technical limitations and error sources. To obtain more reliable results and reduce uncertainties, we developed a new MTI method called logarithmic small baseline subset (Log-SBAS). In this study, we apply Log-SBAS to analyse the post-seismic deformation induced by the 21 May 2003 M_w 6.8 Zemmouri (Algeria) earthquake over a 7-year time span. We then perform a comprehensive assessment of Log-SBAS and compare its performance with that of the conventional small baseline subset (SBAS) method. Our results lead us to propose an alternative post-seismic deformation model, suggesting a visco-elastoplastic relaxation mechanism during the post-seismic phase. This interpretation is supported by the spatio-temporal evolution of deformation and the aftershock sequence of the studied earthquake. Log-SBAS provides a robust framework for long-term post-seismic monitoring of active faults worldwide. The resulting high-resolution map of post-seismic stress relaxation identifies localized zones of persistent deformation and provides important implications for seismic hazard mitigation in this densely populated region of North Africa.</p>