The correct answer is Key Points An Earthquake is what happens when two blocks of the earth suddenly slip past one another. The surface when they slip is called the fault or the fault plane. If an earthquake happens, the surface of the Earth vibrates and vibration can travel to far-off places. The terms that help in understanding earthquakes are: ​Epicentre Seismograph Plate boundary The Epicentre is the point on earth's surface vertically above the hypocentre (or focus), point in the crust where a seismic rupture begins. A seismograph is an instrument used to detect and record earthquakes. Most earthquakes occur at the boundaries where the plates meet. Movement in narrow zones along plate boundaries cause most earthquakes. Most seismic activities occur at three types of plate boundaries: divergent convergent transform Thus, we can say that the terms that help in understanding earthquakes are epicentre, seismograph and plate boundaries.