Lithostatic pressure

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As a lithostatic pressure rsp. (from old / new Greek : λίθος lithos [. m] -, stone ',' rock ') is in geophysics , geology and Geotechnical Engineering that pressure in the lithosphere designated (crust and part of the mantle), the overlying layers of rock by exercise their weight .

This specific pressure creates an isotropic stress field.

definition

The formula is:

The exact spelling is:

Used sizes:
pressure
depth
mechanical tension
strength
area
Density of the rock
gravitational acceleration

While the hydrostatic pressure increases by 1 bar every 10 m  with increasing water depth , the increase in rock layers is about 3 times. The exact proportions depend primarily on the rock density, which is between 2 and 3.3 g / cm³ in the earth's crust ( sediments about 2 g / cm³, granite and limestone 2.7 g / cm³ and gabbro 3.3 g / cm³ ).

In the upper mantle , the rocks are once again more compact (e.g. olivine 3.3 to 4 g / cm³, under very high pressure even 5 g / cm³). Therefore, the exact calculation of internal pressures is one of the most difficult tasks for seismology and applied geophysics .

At the transition between the upper and lower mantle  - at a depth of around 700 km - the pressure is around 25 G Pa , which corresponds to 250,000 times the air pressure .

See also

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