Definition of Asthenosphere – What is, Meaning and Concept

In order to begin to discover the meaning of the term asthenosphere, we are going to know its etymological origin. In this case, we can establish that it is a word of Greek origin that is formed as the sum of several components of that language:
-The prefix “a-”, which can be translated as “without”.
-The noun “sthenos”, which is synonymous with “force”.
-The name “sphaira”, which is equivalent to “sphere”.

The term asthenosphere is not part of the dictionary of the Royal Spanish Academy (RAE). The concept is used to name the mantle layer located between two hundred and fifty and six hundred kilometers deep, below the area called lithosphere.

The asthenosphere is made up of semi-cast and solid materials. Above it floats the lithosphere, a rigid layer composed of the outer sector of the mantle and the earth’s crust. In this way, over the area of ​​the asthenosphere the movement of the tectonic plates.

The equilibrium state called isostasia (which is achieved from the different densities of the parts that make up the surface of the Land) and the Continental drift (the phenomenon caused by the masses of the continents when moving) are possible thanks to the existence of the asthenosphere, where movements are developed through convection.

Another characteristic of the asthenosphere is that it promotes renewal and expansion of the ocean floor. This is because in its composition is basalt, an igneous rock that, through an extrusion process, flows through the oceanic ridges. When he meets the continent, matter sinks and passes underneath, returning to the ocean floor and melting within the asthenosphere by subduction.

In addition to all the above, it is worth taking into consideration other aspects of interest of the asthenosphere, such as the following:
-It is composed of magnesium and iron silicates, in addition to basalt.
-It is identified because, in the same way, it contains what is the magma that volcanoes come to expel when they erupt.
-It is considered to be the weakest region of the upper layer of the Earth, from a mechanical point of view.
-It is also established that it is the region with the highest viscosity.
-Among the most important characters in the establishment of the asthenosphere and its knowledge we find Dutton, Joseph Barrell, Beno Gutenberg or John Tuzo Wilson. Names that should be added to those of Anton Halles, Sengör and Burke …

It is important to mention that, for some scientists, the asthenosphere actually does not exist. There are specialists who argue that continental drift is produced by a solidarity movement of the crust with the mantle, while isostasy would develop between the external part of the core of the Land and the inner part of the mantle.

The aforementioned subject of debate, the one referring to the existence or not of the asthenosphere, which still continues to generate enormous controversy. Hence, at present, there is no position that is considered the correct one in this regard, since there are many studies that are established in one position and in another without being conclusive.