Answer:
The main cause of earthquake is the motion of tectonic plates which occurs due to friction.
Step-by-step explanation:
The tectonic plates moves slowly inside the earth crust but the edges of these plates stuck with each other due to friction that occurs during their contact. When these two plates detached from each other, the force of friction converts in a form of wave energy which can be observed in the form of earthquake. Divergent, convergent, and transform are the three types of plate boundaries which are responsible for earthquake.