The asthenosphere is a significant layer of the Earth’s interior, located beneath the lithosphere. It is composed mainly of the upper part of the mantle and is characterized by its semi-fluid behavior. The asthenosphere extends from about 100 kilometers to approximately 700 kilometers beneath the Earth’s surface.
Essentially, the asthenosphere consists of the following layers:
- Upper Mantle: This is the primary component of the asthenosphere, where the rocks are partially molten and can flow over geological timescales.
- Transition Zone: This layer lies just below the asthenosphere, where the mantle material can change in its mineral composition due to variations in temperature and pressure.
The asthenosphere is crucial for the movement of tectonic plates, allowing them to glide over the semi-fluid underlying material. This movement is essential for seismic activity and the formation of various geological features on the Earth’s surface.