Land slides can be caused by earthquakes, floods, storm winds, tornadoes, or mud flows. Land slides can be caused by all of this natural occurrences, they usually appear on places where the ground is more labile, has little or no vegetation, is heavily affected by erosion, there's shallow underground waters, and always the land is under some angle, usually bigger and it is a steep land, so any bigger disturbance causes big masses of ground to move downwards, thus the land slide appears.