Question

why is the upper mantle called the asthenosphere​

Answer 1

Answer:

The upper mantle is called asthenosphere, “astheno” is a Greek word meaning 'weak'. It is called weak layer because it is in liquid state where rock material deforms more readily, and magma formation takes place.

Answer 2

Answer:

The Mantle is the layer beneath the earths crust.It consists of two layers: upper and lower mantle.the upper layer is called asthenosphere. "astheno" is a greek word meaning 'weak'.It is called weak layer because it is in liquid state where rock material deforms more readily, and magma formation takes place.