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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).
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 environment. [1]
Interaction of the asthenosphere, lithosphere, and surface though the mantle process of subduction at an oceanic-continental plate boundary. Volcanism which originates from the mantle occurs on the surface. Interaction of the asthenosphere, lithosphere, and surface through the mantle process of slab break-off. Grey indicates crust, purple ...
Below the asthenosphere, the mantle is again relatively rigid. The Earth's mantle is divided into three major layers defined by sudden changes in seismic velocity: [ 6 ] the upper mantle (starting at the Moho, or base of the crust around 7 to 35 km [4.3 to 21.7 mi] downward to 410 km [250 mi]) [ 7 ]
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.
But sometimes, Earth doesn’t always just have a single magnetic North and South Pole. Evidence suggests that, for hundreds to thousands of years at a time, our planet has had four, six, and even ...
The two axes were separated by around 100 km from east to west and 300 km from north to south. When the two axes developed to full seafloor spreading, the 100x300 km continental region between the two rifts formed the Iceland microcontinent which underwent diffuse extension and shear along several north-oriented rift axes, and basaltic lavas ...
The subduction of bathymetric highs such as aseismic ridges, oceanic plateaus, and seamounts has been posited as the primary driver of flat slab subduction. [3] The Andean flat slab subduction zones, the Peruvian slab and the Pampean (Chilean) flat slab, are spatially correlated with the subduction of bathymetric highs, the Nazca Ridge and the Juan Fernandéz Ridge, respectively.