asthenosfäärist

Asthenosphere is the highly viscous, mechanically weak, and ductile region of the upper mantle of Earth. It lies below the lithosphere, which is the rigid outer part of the Earth, consisting of the crust and upper mantle. The asthenosphere extends from a depth of about 80 to 200 kilometers below the Earth's surface, though its exact thickness varies.

The asthenosphere is characterized by temperatures high enough that rocks begin to soften and deform, but not high enough to melt completely. This partial melting allows the rocks to flow very slowly over geological timescales. This slow convection within the asthenosphere is the driving force behind plate tectonics, the movement of the Earth's lithospheric plates.

The behavior of the asthenosphere is crucial for understanding phenomena such as earthquakes, volcanic activity, and the formation of mountain ranges. It acts as a lubricating layer, enabling the rigid lithospheric plates to slide and interact with each other. Variations in the temperature and composition of the asthenosphere can lead to different types of geological activity. For instance, areas where the asthenosphere is hotter and less viscous tend to be more tectonically active.