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The asthenosphere (from Ancient Greek ἀσθενός (asthenós) 'without strength') is the mechanically weak [1] and ductile region of the upper mantle of Earth. It lies below the lithosphere , at a depth between c. 80 and 200 km (50 and 120 mi) below the surface, and extends as deep as 700 km (430 mi).
Earth's crust and mantle, Mohorovičić discontinuity between bottom of crust and solid uppermost mantle. Earth's mantle extends to a depth of 2,890 km (1,800 mi), making it the planet's thickest layer. [20] [This is 45% of the 6,371 km (3,959 mi) radius, and 83.7% of the volume - 0.6% of the volume is the crust].
Earth's inner structure can be described both chemically (crust, mantle, and core) and mechanically. The lithosphere–asthenosphere boundary lies between Earth's cooler, rigid lithosphere and the warmer, ductile asthenosphere. The actual depth of the boundary is still a topic of debate and study, although it is known to vary according to the ...
Map showing Earth's principal tectonic plates and their boundaries in detail. These plates comprise the bulk of the continents and the Pacific Ocean.For purposes of this list, a major plate is any plate with an area greater than 20 million km 2 (7.7 million sq mi)
Earth systems across mountain belts include the asthenosphere (ductile region of the upper mantle), lithosphere (crust and uppermost upper mantle), surface, atmosphere, hydrosphere, cryosphere, and biosphere. Across mountain belts these Earth systems each have their own processes which interact within the system they belong.
Earth's mantle is a layer of silicate rock between the crust and the outer core. It has a mass of 4.01 × 10 24 kg (8.84 × 10 24 lb) and makes up 67% of the mass of Earth. [ 1 ] It has a thickness of 2,900 kilometers (1,800 mi) [ 1 ] making up about 46% of Earth's radius and 84% of Earth's volume.
The modern understanding of the Earth's upper mantle is that there are two distinct components - the lithospheric part and the asthenosphere. The lithosphere, which includes the continental plates , acts as a brittle solid whereas the asthenosphere is hotter and weaker due to mantle convection.
The idea is that Earth's most outer layer, known as the lithosphere, that is made up of the crust and mantle is divided into extensive plates of rock. [8] [26] These plates sit on top of partially molten layer of rock known as the asthenosphere and move relative to each other due to convection between the asthenosphere and lithosphere. [26]