Asthenosphere - Evidence For The Existence Of The Asthenosphere, Properties Of The Asthenosphere, The Asthenosphere In Plate Tectonic Theory
earth planet structure layer
The asthenosphere is the layer of Earth situated at an average depth of about 62 mi (about 100 km) beneath Earth's surface. It was first named in 1914 by the British geologist Joseph Barrell, who divided Earth's overall structure into three major sections: the lithosphere, or outer layer of rock-like material; the asthenosphere; and the centrosphere, or central part of the planet. The asthenosphere gets its name from the Greek word for weak, asthenis, because of the relatively fragile nature of the materials of which it is made. It lies in the upper portion of Earth's internal structure traditionally known as the mantle. Scientists have not seen the asthenosphere of Earth, but its existence has a profound effect upon the planet and the manner in which the Earth's crust behaves. For anyone living near a plate boundary on Earth, the asthenosphere contributes mightily to the uneasy geologic conditions which may plague the area.
Additional Topics
Geologists are somewhat limited as to the methods by which they can collect information about Earth's interior. For example, they may be able to study rocky material ejected from volcanoes and lava flows for hints about properties of the interior regions. Generally speaking, however, the single most dependable source of such information is the way in which seismic waves are transmitted thro…
The material of which the asthenosphere is composed can be described as plastic-like, with much less rigidity than the lithosphere above it. This property is caused by the interaction of temperature and pressure on asthenospheric materials. Any rock will, of course, melt if its temperature is raised to a high enough temperature. However, the melting point of any rock (or of any material) is also a…
The asthenosphere is now thought to play a critical role in the movement of plates across the face of Earth's surface. According to plate tectonic theory, the lithosphere consists of a relatively small number of very large slabs of rocky material. These plates tend to be about 60 mi (100 km) thick and in most instances many thousands of miles wide. They are thought to be very rigid themselv…
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User Comments
over 3 years ago
The heat from the asthenosphere comes from a combination of the incredible pressure caused by the gravitational force as well as the slow decay of radiactive isotopes from radiactive materials in the earth's interior.
almost 4 years ago
Helpfull - but does not explain the heat source of the Asthenosphere.
It can't be just pressure as various layers below (hense more pressure) this sphere are not semi liquid - some are solid.
It can't be just radioactive decay as other sphere's also have this action.
It can't be just gravity from Moon and Sun that causes this sphere to be hot, as gravity affects the whole earth and the centre of the earth is solid.
So what is it???