The asthenosphere (from an invented Greek ἀσθενός a + ''sthenos "without strength") is the region of the Earth between 100 and 200 km (~ 62 and 124 miles) below the surface — but perhaps extending as deep as 400 km (~ 249 miles) — that is the weak or "soft" zone in the upper mantle. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International A mile is a unit of Length, usually used to measure Distance, in a number of different systems including Imperial units United States The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided It lies just below the lithosphere, which is involved in plate movements and isostatic adjustments. The lithosphere (IPA, from the Greek λίθος for "rocky" + σφαίρα for "sphere" is the solid outermost shell of a rocky Planet. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Isostasy (Greek isos = "equal" stásis = "standstill" is a term used in Geology to refer to the state of gravitational equilibrium between the In spite of its heat, pressures keep it plastic, and it has a relatively low density. Seismic waves, the speed of which decrease with decreasing rigidity of a medium, pass relatively slowly through the asthenosphere, the cue that originally alerted seismologists to its presence; thus it has been given the name low-velocity zone. Seismology (from Greek grc σεισμός seismos, "earthquake" and grc -λογία -logia) is the scientific study of Earthquakes Generally rigidity refers to inflexibility or resistance to change Seismology (from Greek grc σεισμός seismos, "earthquake" and grc -λογία -logia) is the scientific study of Earthquakes
Under the thin oceanic plates the asthenosphere is usually much nearer the seafloor surface, and at mid-ocean ridges it rises to within a few kilometres of the ocean floor. A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by
The upper part of the asthenosphere is believed to be the zone upon which the great rigid and brittle lithospheric plates of the Earth's crust move about. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Due to the temperature and pressure conditions in the asthenosphere, rock becomes ductile, moving at rates of deformation measured in cm/yr over lineal distances eventually measuring thousands of kilometers. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere In this way, it flows like a convection current, radiating heat outward from the Earth's interior. Convection in the most general terms refers to the movement of molecules within Fluids (i Above the asthenosphere, at the same rate of deformation, rock behaves elastically and, being brittle, can break, causing faults. In Geology a fault, or fault line, is a planar rock fracture which shows evidence of relative movement The rigid lithosphere is thought to "float" or move about on the slowly flowing asthenosphere, creating the movement of crustal plates described by Plate tectonics theory. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere
Although its presence was suspected as early as 1926, the worldwide occurrence of the asthenosphere was confirmed by analyses of earthquake waves from the Great Chilean Earthquake of May 22, 1960. Year 1926 ( MCMXXVI) was a Common year starting on Friday (link will display the full calendar of the Gregorian calendar. An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer The 1960 Valdivia earthquake or Great Chilean Earthquake (Gran terremoto de Valdivia of 22 May, 1960 is the most powerful Earthquake ever Events 334 BC - The Greek army of Alexander the Great defeats Darius III of Persia in the Battle of the Granicus. Year 1960 ( MCMLX) was a Leap year starting on Friday (link will display full calendar of the Gregorian calendar.
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References
- Donald L. Turcotte and Gerlad Schubert. Geodynamics, 2nd ed. , Cambridge University Press 2001
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