{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# T p assuming that the stress in the earth’s

This preview shows pages 43–46. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: T P Assuming that the stress in the earth’s interior is equal to hydrostatic pressure ), ( g h then pressure gradient towards the centre of the earth. ) 2 ( g dr dp r is the radius of the earth. The negative sign implies pressure increase with decrease in radius. Consider a homogeneous layer in which the t temperature variation is adiabatic then. - 44 - e i p dp dp v dv dp . / / ) 3 ( / p dp dp But ) 4 ( dp dp d dp dr dp Use (2) and (3) in (4) ) 5 ( g dr d But so r GM g , 2 ) 6 ( 2 r GM dr d Equation (6) is applicable to region of uniform composition within the earth, which is, starting from mantle down. It shows uniform density increase (Fig.1) Where = adiabatic incompressibility (i.e. bulk modulus) M = Mass of the region of the earth with the earth less by the mass of the crust r = radius of the earth’s region with uniform composition G = Gravitational constant - 45 - 3.2 Variation of Pressure P with Depth This has to do with the pressure distribution and variation of acceleration due to gravity. ) 1 ( Re 2 r Gm g that call ) 2 ( g r P and So pressure gradient ) 3 ( 2 r Gmp dr dp Equation 3 shows that pressure decreases with depth, i.e. as r decreases (Fig.1) Also; it shows that pressure has direct relation with the density. 3.3 Variation of Acceleration due to gravity with depth Recall that . 2 r GM g So, variation of g with depth can be calculated using the relation above. Its value does not differ by more than 1% from 990 km until a depth of 2400 km is reached where it decreases to zero (Fig.1) 3.4 Variation of Pressure P and S waves with Depth In seismology P and S waves are used to study the interior of the solid earth. P- Wave is a longitudinal wave that can pass through liquid, solid and gas. S- Wave is a Wave is a longitudinal wave that can pass through liquid, solid and gas....
View Full Document

{[ snackBarMessage ]}

### Page43 / 48

T P Assuming that the stress in the earth’s interior is...

This preview shows document pages 43 - 46. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online