What is the main function of the asthenosphere?

The asthenosphere plays a critical role in the movement of tectonic plates due to its unique physical properties. Located just beneath the lithosphere, the asthenosphere is made up of partially molten rock that is capable of flowing over geological timescales. This semi-fluid layer allows the rigid tectonic plates situated above it in the lithosphere to drift and move.

The movement of these plates is driven by various forces, including mantle convection, slab pull, and ridge push, all of which are made possible by the asthenosphere's ability to deform and accommodate changes in pressure and temperature. Without its presence, tectonic plates would be unable to shift, leading to the stagnation of geological processes such as earthquakes, volcanic activity, and mountain building. Thus, the primary function of the asthenosphere is indeed to facilitate the movement of tectonic plates.