Layer of the interior of the Earth that extends approximately between 50 and 150 km deep, formed mainly by partially molten plastic rocks that can deform: the asthenosphere is located between the lithosphere and the mesosphere.
Explanation:
The asthenosphere is composed of ductile silicate materials, in solid state and partially or totally semi-molten (according to their depth and / or proximity to magma bags), which allow continental drift and isostasis. On it the tectonic plates move.
Characteristics of the asthenosphere
The asthenosphere is a part of the upper mantle, just below the lithosphere that is involved in tectonic plate movements and isostatic adjustments.
Despite its heat, the pressure keeps it like plastic and has a relatively low density. Seismic waves pass relatively slowly through the asthenosphere, compared to the mantle that covers the lithosphere, which is why it has been called the low-speed zone.
This was the observation that originally alerted the seismologists to their presence and gave some information about their physical properties, such as the speed of the seismic waves that decreases as stiffness decreases. Under the thin oceanic plates the asthenosphere is generally much closer to the surface of the seabed, and rises a few kilometers from the ocean floor.
Due to the temperature and pressure conditions in the asthenosphere, the rock becomes ductile, moving at a deformation rate that is measured in cm / year at linear distances that finally reach thousands of kilometers. In this way, it flows like a convection current, radiating heat outward from inside the Earth. Above the asthenosphere, at the same rate of deformation, the rock behaves elastically and, if fragile, can break, causing failures. The rigid lithosphere is believed to "float" over the asthenosphere from which it flows slowly, creating the movement of tectonic plates.
