Which factors are involved in earthquakes formation (multiple choice)

A. rocks breaking

B, stress decreases

C, faults that remain stationary

D, movement below surface

Which statement describes the Mercalli scale?

This scale produces a single rating for earthquakes that reach the surface

Or

This scale measures magnitude of an earthquake based on their size?

A. rock breaking and D movement below ground

1 - Option (A) and (D)

2 - Mercalli scale measures earthquake magnitude depending on its size

Explanation:

Earthquake occurs due to the sudden shaking of the earth. During an earthquake, seismic waves are produced, namely P wave and S wave, and this waves propagates through the interior of the earth depending upon its magnitude and intensity, thus travelling below the earth's surface.

Due to this wave propagation the rocks breaks and adjust themselves and the faulting occurs along the weak zones.

According to the Mercalli scale, the earthquake is measured in terms of intensity of the shaking of the ground and the size. If a small area is affected then its magnitude is less but if an earthquake affects a large area then it is a severe one.