An earthquake is a shaking of the ground caused by the sudden breaking and movement of large sections (tectonic plates) of the earth's rocky outermost crust. The edges of the tectonic plates are marked by faults (or fractures). Most earthquakes occur along the fault lines when the plates slide past each other or collide against each other.
Landslides are dependant upon plate movements of the earth.They don't have fixed intervals in which they can occur,that is seismologists are always monitoring plate movements in order to help them predict earthquarke activities