Difference between Lithosphere and Asthenosphere

Composition of the earth is not the same all the way but it varies a lot layer-by-layer. The core of the earth is not completely solid, with similar characteristics but it is constantly moving interacting combination of different layers of minerals. Two of such layers are lithosphere and asthenosphere, which interact with each other to make the appearing surface of this planet. There are huge differences between these two layers of earth and they possess entirely separate characteristics.

Lithosphere originated from the Greek words, “lithos” (meaning rocky) and “sphaira” (meaning sphere), and forms the outermost shell of a rocky planet. It comprises of the crust and the portion of the upper mantle that behaves elastically on time scales for thousands of years.

Asthenosphere also originated from the Greek words, “asthenes” (meaning weak) and “sphaira” (meaning sphere). It is the highly viscous, mechanically weak and ductility-deforming region of the upper mantle of this planet. Asthenosphere lies beneath lithosphere and starts at about 100 to 200 kilometres below the surface.

Instructions

  • 1

    Lithosphere

    The very first difference between these two layers is there location and extend. Lithosphere starts from the surface of the earth and extends to approximately first 50 miles below towards the core of the planet. This extend of lithosphere might vary at different locations. Lithosphere can be divided into two parts, the top of the mantle and the crust itself. The movement of lithosphere involves the movement of massive tectonic plates, which constitute the crust of the earth. It is the movement of lithosphere which causes earthquakes on the surface. The upper part of lithosphere is extremely solid but it also includes the uppermost part of the mantle, which is in liquid form and mobile. Lithosphere mainly consists of granite and basalt but more than 80 other elements are also found in the crust.

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    Asthenosphere

    Asthenosphere lies beneath lithosphere and begins at about 155 miles below the surface of the earth. It mainly consists of liquid mantle and that is why it is more mobile than lithosphere to move. The movement of this liquid mantle causes the movement in the tectonic plates of lithosphere, resulting in earthquakes. Hence, it is actually asthenosphere which causes earthquakes to happen, rather than lithosphere itself. Asthenosphere mainly comprises of ferro-magnesium silicates and lesser variety of combinations is found in this layer.

    Image Courtesy: geus.dk

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