With reference to Earthquake consider the following statements 1 It occurs due to release of energy ...........

Geography (CDS) World Physical Aspects

With reference to Earthquake consider the following statements:

1. It occurs due to release of energy that has been built up during the stress of increasing deformation of rocks.

2. The point where energy is released is known as epicentre and the point directly above it on earth"s surface is known as focus.

3. Highest concentration of earthquake is found along the convergent boundary zone of Himalayan belt.

4. Earthquake waves can get amplified when they pass through soft ground or soil.

Which of the statement(s) given above is/are correct?

1 and 4 only

1 and 3 only

2 and 3 only

1, 2, 3 and 4

EXPLANATION:

STATEMENT 2 AND 3 ARE INCORRECT. The point where the energy is released is called the focus of an earthquake.

Heaviest concentration of earthquake found along circum-pacific belt. 70% earthquakes occur in the circum-pacific belt.
The release of energy occurs along a fault. Rocks along a fault tend to move in opposite directions. As the overlying rock strata press them the friction locks them together. However their tendency to move apart at some point of time overcomes the friction. As a result the blocks get deformed and eventually they slide past one another abruptly. This causes a release of energy and the energy waves travel in all directions.
The point where the energy is released is called the focus of an earthquake. Alternatively it is called the hypocentre. The point on the surface nearest to the focus is called epicentre.
Heaviest concentration of earthquake found along circum-pacific belt. 70% earthquakes occur in the circum-pacific belt.
Soils can greatly amplify the shaking in an earthquake. Passing from rock to soil seismic waves slow down but get bigger. Hence a soft loose soil may shake more intensely than hard rock at the same distance from the same earthquake.