Plain Language Summary We used continuous GPS positioning data to study the viscosity distribution at depth and its time variation following the 2010 M-w 8.8 Maule, Chile, earthquake. We find that the viscosities in the volcanic/mountain range regions, where deep rocks are expected hot, are relatively low (i.e., the materials are in weak state prone to flow easily), while the viscosities in far regions, where an ancient cold crust is expected, are relatively high (i.e., the materials are too strong to flow). This finding can, therefore, be related to the temperature distribution at depth. Furthermore, we find that the viscosities in all regions except the region of ancient crust increase with time and the rate of viscosity recovery decreases with the distance to the earthquake location. This phenomenon can, therefore, be related to the earthquake-induced stresses. Another interesting thing found in this study is that the ancient crust is likely not influenced much by the earthquake and behaves very strong in all the observation time. In all, we propose that both temperature and earthquake stresses control the rock strengths following a great earthquake. This study thus contributes to our understanding of the stress evolution at depth through the earthquake cycle and hence mechanisms of the earthquake happening.