Question

why is the upper Mantle called the asthenosphere ​

Answer 1

Answer:

because The upper mantle is not uniform throughout.Below the lithosphere is a layer of upper mantle called the asthenosphere.This is made up rock that is fluid and can move.It is this fluidity that powers the movement of the tectonic plates of the Earth's crust.the hot,fluid asthenosphere below the lithosphere this lower level is responsible for tectonic movement of plates.