highly viscous, mechanically weak and ductile region of the Earth's mantle

The asthenosphere is part of earth's mantle. It is about 100 km to 350 km under the surface.[1] It is the lower part of the upper mantle, and behaves as a hot viscous liquid.

Earth cutaway

It consists of hot, weak material that can be deformed like silly putty. That means it is capable of gradual flow. It is under the lithosphere.


  1. "St. Diego State University Department of Geological Sciences". Archived from the original on 2011-03-03. Retrieved 2007-06-01.