Today we had our 4th geography
class.
Earth’s interior:
(1) crust
(2) mantle
(3) outer core
(4) inner core
Direct sources of earth’s interior:
(1)
Volcanic activity:
Using
lava ejected from the volcanoes the composition of minerals in the earth’s
interior can be found but it is difficult to ascertain the depth of earth’s
interior
(2) Mining and drilling:
During
mining and drilling the temperature of the earth’s increases with its depth.
Indirect sources of earth’s interior:
(1)
temperature ,pressure and
density:
The
statistical analysis of temperature , pressure and density from various mining
and drilling sites gives more incites about earth’s interior.
(2) Asteroids and meteoroids:
By
analyzing the formation of asteroids and meteoroids we can identify the origin
of earth.
(3)Gravitational force:
The
magnetic lines of force are greater at the poles and lesser at the equator
using this we can find the depth of a place.
(4)Magnetic properties:
The
magnetic properties of a material revels the distribution of minerals in the
earth’s interior.
(5)Seismic activity:
The
sudden release of energy from the earth’s crust generates seismic waves inside
the earth’s interior which gives lots of incites about earth’s interior.
Interior of the earth:
(1)Crust:
The
crust id divided into upper[continental] crust and lower[oceanic] crust. It is
the outermost layer of the earth’s interior with average density of 2.7g/cm^3.
(2)Mantle:
It
extends from 30-2900 km depth with average density of 3.9g/cm^3.the upper
mantle is called asthenosphere where the liquid magma resides.
(3)Core:
The
core extends from 2900 km to the center of the earth. It is also divided into
outer core[made up of liquid] and inner core[made up of solid] with average density
of 13g/cm^3.
It is also called barrysphere which is
deepest and most inaccessible zone of earth’s interior. It is made up of nickel
and iron.
Earthquake:
It is the
shaking of earth surface caused due to sudden release of energy along a fault
in the crystal rocks which generate waves in the earth’s interior called
seismic waves (or) earthquake waves which travels in all directions.
Hypo center or focus:
The
point at which the energy is released in the earth’s interior.
Epicenter:
The
point on the earth surface vertically above the focus of the earthquake is
called epicenter.It is the closest point to the focus.
This brief explanation helps in better understanding of earth’s interior.
Credits : Leo Hema Nanthini
