Geology and Earth Structure

The asthenosphere is the highly viscous, mechanically weak, and ductile region of the upper mantle of the Earth. It lies below the lithosphere and allows the tectonic plates to move.

Rift valleys and horsts are geological features formed by faulting, which is the fracturing and displacement of rock layers due to tectonic forces.

Earthquakes are primarily caused by the movement and collision of tectonic plates, which release energy stored in the Earth's crust.

Uttarakhand is highly seismically active and falls under Seismic Zones 4 and 5, which are the highest risk categories in India.

Yes, it is correct. Seismic focus is the point of origination of earth quake waves. It lies within the crust of the earth.

Disturbances deep inside the earth's crust cause an earthquake.

The movement of earth's plates causes earthquake.

The power of an earthquake is expressed in terms of a magnitude on a scale called Richter scale.

The seismic waves are recorded by an instrument called seismograph.

The weak zones are also called seismic or fault zones.

The excessive shrinking of the geosynclines, caused folding and the surplus sediments were raised as the Himalayan mountains.

A depression more than one kilometre in diameter caused by the collapse of the centre of a volcano is called caldera.

The circum-Pacific belt is highly prone to the occurrence of earthquakes because it is a zone of convergent plate boundaries.

The really destructive earthquakes have magnitudes higher than 7.

The disturbances occur deep down inside the uppermost layer of the earth called the crust.