For a period of approximately one million years after it was formed, the planet earth was a hot mass of molten matter in which there was no atmosphere. Given the gravitational force, heavy metals such as nickel and iron were dragged to the center of the earth and the light metals rose to the surface. When the earth began to cool, the crust began to solidify and the original earth formed. Even so, the deeper layers below the surface of the earth remain hot due to the reactions that take place there. One of these layers is called Asthenosphere, that word originated from the Greek word asthenis meaning weak. It was named in this way due to the instability of its components.
The asthenosphere is the ductile part of the upper terrestrial mantle. It extends from the lithosphere to the lower mantle of more than 700 kilometers. The asthenosphere lies between the lithosphere and the mesosphere. Therefore, the depth of the asthenosphere depends directly on the thickness of the lithosphere. The latter varies between about 100 km under the oceans (a few kilometers in the ocean crevices) and about 170 km under the continents.
Some of its characteristics are:
It is composed of matter in the molten or semi-molten state. Its temperature ranges from 1350 ° C to 2800 ° C.
It is composed mainly of iron and magnesium silicates.
This layer is important for the movement of the tectonic plates of the earth's crust, they float in the semisolid asthenosphere.
The melting point of the substances in the asthenosphere is affected by the pressure exerted by the lithosphere above, taking into account that the pressure exerts a direct influence on the point of fución of a substance.
It is called a low-speed zone since seismic waves travel through this layer with a lower speed compared to the lithosphere.
The asthenosphere is of great geological importance for the mantle of the Earth. This layer is responsible for the creation of new crust in the earth, that is, it allows the formation of more earth. This process takes place in the oceanic ridges, where convection pushes the asthenosphere to the surface. The tectonic plates found in the asthenosphere contribute to the movement of the continental masses with respect to each other, due to plate tectonics. Convection currents that have their origin in this layer are very important because they are what define the different movements of the plates. It is also responsible for the creation of new crust in the earth
Fuente
@cervantes. No te olvides de votarles como witness en esta página: