It may not show well at lower resolutions and colour depths. It such terrain, it is impossible to regrade slopes to stable angles. The scale of landsliding may be too great to do anything about its causes - we can only try to reduce its effects. In the diagram above we have the major elements of a rockfall. There is a source area, in this case a layer of jointed rock.
Several mechanisms suggest themselves.
Secondly, if the rock warms in the sun, the mass expands and joints open. Any dirt or gravel which falls into the joints stops them closing when the rock next cools. Thirdly, the stratum could be undermined. This could be because of erosion. It could be that the underlying rock softens or weathers.