INSIGHT UPSC QUIZ

ANS. (C) 
An earthquake is the result of a sudden release of energy in the Earth’s crust that creates seismic waves. The world’s earthquakes are not randomly distributed over the Earth’s surface. They tend to be concentrated in narrow zones. An explanation is to be found in plate tectonics, a concept which has revolutionized thinking in the Earth’s sciences. Plate tectonics tells us that the Earth’s rigid outer shell (lithosphere) is broken into a mosaic of oceanic and continental plates which can slide over the plastic asthenosphere, which is the uppermost layer of the mantle. The plates are in constant motion. Where they interact, along their margins, important geological processes take place, such as the formation of mountain belts, earthquakes, and volcanoes.