THE INNER CORE
◇ Inner core extends from the centre of the earth to 5100 km below the earth’s surface.
◇ Inner core is generally believed to be composed primarily of iron (80%) and some nickel (nife).
◇ Since this layer can transmit shear waves (transverse seismic waves), it is solid. (When P-waves strike the outer core – inner core boundary, they give rise to S-waves).
◇ Earth’s inner core rotates slightly faster relative to the rotation of the surface.
◇ The solid inner core is too hot to hold a permanent magnetic field.
◇ The density of the inner core ranges from 12.6 g/cm3 to 13 g/cm3.
◇ The core (inner core and the outer core) accounts for just about 16 percent of the earth’s volume but 33% of the earth’s mass.
◇ Scientists have determined the temperature near the Earth’s centre to be 6000֯C.
◇ At 6000°C, this iron core is as hot as the Sun’s surface, but the crushing pressure caused by gravity prevents it from becoming liquid.
