This paper concerns the determination of the stress deviator from a set of striated faults or of focal mechanisms of earthquakes. Southern Tibet and the Cuzco region of the High Andes illustrate the applied methodology. Then, the spatial and temporal changes in the tectonic regimes of Tibet and Central Andes are briefly examined. The Quaternary-Present-day stress patterns in these two high plateaus favour models explaining the spatial changes in the state of stress at a large wavelength as a result of a compensated elevated topography. Major temporal changes in the tectonic regimes are attributed tentatively to uplift for the Tibetan plateau and, for the already elevated Andean Plateau, to changes in the magnitude of the boundary forces due to subduction processes.