Question

The point from where an earthquake originates is called
A. Crust
B. Earth
C. Surface
D. Focus

Answer 1

Hint:An earthquake is an intense shaking of the earth’s surface which is the result of a sudden release of stored energy. The point where the earthquake originates is also known as a hypocenter.

Complete answer:
An earthquake is the vigorous shaking of the earth’s surface which is due to the sudden release of stored energy in the Earth's crust that creates seismic waves.
Earthquakes occur when large blocks of the Earth's crust move suddenly past one another at a fault. The pieces of the Earth’s crust are caused to move by the force of the plate tectonics but sometimes the pieces do not slide smoothly past one another. This is due to the friction present along the fault - jagged edges that obstructs the blocks of rock, thus making it difficult for them to move past each other. Sometimes they adhere together temporarily. When the pieces of rock overcome the obstruction, energy is released. The release of energy causes an intense shaking at the ground surface.
The point inside the Earth where an earthquake originates is known as the focus (or hypocenter) of the earthquake. The point directly above the focus at the surface of the earth is called the epicenter of the earthquake. At the epicenter, the most vigorous shaking is caused during an earthquake. Sometimes the ground surface breaks across the fault. At times the movement is deep underground and the surface does not break.

Hence the correct answer is option D.

Note:Earthquakes are measured with the help of a device known as seismometer, commonly known as a seismograph. The magnitude of an earthquake is conventionally reported with the help of a Richter scale or a related Moment scale ( earthquakes having a magnitude of 3 or lower are hard to notice while the ones with a magnitude 7 causing serious damage over large areas).