Earth cutaway from core to exosphere.

The asthenosphere (from an invented Greek ἀσθενός a + ''sthenos "without strength") is the region of the Earth between 100-200 km below the surface — but perhaps extending as deep as 400 km — that is the weak or "soft" zone in the upper mantle. It lies just below the lithosphere, which is involved in plate movements and isostatic adjustments. In spite of its heat, pressures keep it plastic, and it has a relatively low density. Seismic waves, the speed of which decrease with the softness 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. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... This article is about Earth as a planet. ... The planetary core consists of the innermost layer(s) of a planet. ... [fAgot png|thumb|200px|right|Atmosphere diagram showing the exosphere and other layers. ... This article is about Earth as a planet. ... ‹ The template below (Unit of length) is being considered for deletion. ... Earth cutaway from core to exosphere. ... The tectonic plates of the Lithosphere on Earth. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... Isostasy is a term used in Geology to refer to the state of ice above stasy and is angravitational equilibrium between the Earths lithosphere and asthenosphere such that the tectonic plates float at an elevation which depends on their thickness and density. ... For other uses, see Plasticity. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. ...

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, formed by plate tectonics. ...

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. 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. In this way, it flows like a convection current, radiating heat outward from the Earth's interior. Above the asthenosphere, at the same rate of deformation, rock behaves elastically and, being brittle, can break, causing faults. 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. The tectonic plates of the world were mapped in the second half of the 20th century. ... Fig. ... The use of water pressure - the Captain Cook Memorial Jet in Lake Burley Griffin in Canberra, Australia. ... This balancing rock, Steamboat Rock stands in Garden of the Gods park in Colorado Springs, CO The rocky side of a mountain creek near Orosí, Costa Rica. ... Convection in the most general terms refers to the internal movement of currents within fluids (i. ... Geologic faults, fault lines or simply faults are planar rock fractures, which show evidence of relative movement. ... The tectonic plates of the world were mapped in the second half of the 20th century. ...

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 stored energy in the Earths crust that creates seismic waves. ... Map showing the areas affected by the tsunami The Great Chilean Earthquake or Valdivian Earthquake (Terremoto de Valdivia in Spanish) of 22 May 1960 is the most intense earthquake ever recorded, rating a 9. ... is the 142nd day of the year (143rd in leap years) in the Gregorian calendar. ... Year 1960 (MCMLX) was a leap year starting on Friday (link will display full calendar) of the Gregorian calendar. ...

External link

• San Diego State University, "The Earth's internal heat energy and interior structure"