Interior of the Earth Test - 1

It is made up of heavier rocks having density of 3 g/cm³. This type of rock found in the oceanic crust is basalt. 

The upper portion of the mantle is called the asthenosphere. The word astheno means weak. It is considered to be extending upto 400 km. It is the main source of magma that finds been released out in the recent past. The layer below the solid crust is the mantle. It has a higher density than that of the crust. The mantle contains a weaker zone called the asthenosphere.

The shifting rock in an earthquake causes vibrations called seismic waves that travel within the Earth or along its surface. The four main types of seismic waves are P waves, S waves, Love waves, and Rayleigh waves.

When seismic waves pass across the boundary between two different materials, the waves refract, the waves reflect and the waves change in velocity.

The Continental Crust is also called the SiAl layer.

The continental crust is thicker in the areas of major mountain systems. It is as much as 70 km thick in the Himalayan region.

Oxygen is the most abundant element in the earth's crust. 

P-wave takes 16 to 20 minutes to travel through the Earth.

The average distance from the surface of the earth to its center is 6,371 km or 3,959 miles. So, the approximate distance from the surface to the center of the Earth is 4,000 miles.

The interior of the earth can only be understood by Direct and Indirect methods.