The asthenosphere is a layer of the Earth's mantle.
Asthenosphere is a term that is not part of the dictionary of the Royal Spanish Academy ( RAE ). The concept is used to name the layer of the Earth's mantle located between two hundred and fifty and six hundred kilometers deep, below the area called lithosphere .
Before continuing to discover the meaning of asthenosphere, let's 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 said language:
- The prefix a- , which can be translated as "without" .
- The noun sthenos , which is synonymous with "strength."
- The name sphaira , which is equivalent to "sphere" .
Characteristics of the asthenosphere
The asthenosphere is composed of semimolten and solid materials . Above it floats the lithosphere, a rigid layer composed of the external sector of the mantle and the Earth's crust . In this way, the movement of tectonic plates occurs in the area of the asthenosphere.
The state of equilibrium called isostasy (which is achieved from the different densities of the parts that make up the Earth 's surface) and continental drift (the phenomenon caused by the masses of the continents when they move) are possible thanks to the existence of the asthenosphere, where movements develop through convection.
Another characteristic of the asthenosphere is that it promotes the renewal and expansion of the ocean floor . This is because its composition includes basalt, an igneous rock that, through an extrusion process, flows along the oceanic ridges. When it meets the continent , the matter sinks and passes underneath, returning to the ocean floor and melting within the asthenosphere by subduction.
The existence of the asthenosphere is a matter of debate.
Other information of interest
In addition to everything stated above, other aspects of interest in the asthenosphere must be taken into consideration:
- It is composed of magnesium and iron silicates, in addition to basalt.
- It contains the magma that volcanoes expel when they erupt.
- It is considered to be the weakest region of the Earth's upper layer, from a mechanical point of view.
- It is also established that it is the region that has the highest viscosity.
- Among the most important personalities in the establishment of the asthenosphere and its knowledge we find Clarence Dutton, Joseph Barrell, Beno Gutenberg, John Tuzo Wilson and Anton Halles .
About the existence of the asthenosphere
It is important to mention that, for some scientists, the asthenosphere does not actually exist . There are specialists who maintain that continental drift is produced by a movement of the crust with the mantle, while isostasy would develop between the external part of the Earth 's core and the internal part of the mantle.
This topic of debate still continues to generate enormous controversy. Hence, currently, there is no position that is considered accurate in this regard, since there are many studies that are established in one position or another without being able to be conclusive.