As, when and where forces tending to induce failure dominate over those tending to resist failure, mass becomes unstable.

In devising a monitoring system, cost-benefit ratio has to be kept in mind in all cases because such systems are invariably expensive.

It has been observed that most materials are stable up to a certain angle of slope. This is called critical angle of slope or also called as angle of repose and varies from 35° for unconsolidated sediments to 90° for perfectly crystalline unjointed rocks.

In unconsolidated deposits, loose, inherently weak rock masses and weared top surface, sliding commonly takes place along curved shear surfaces.

Internal factors include such cases, which tend to reduce shearing strength of soil or rock mass by virtue of which it had remained stable at a given position on ground.

Oiling of slope surfaces, electro-osmosis and heating of slope material have been also used in different countries to stabilize slopes by reducing chances of infiltration during heavy rains.

The dip factor has to be kept in mind while giving cuts in stratified rocks. it may be possible to explain that cuts parallel to dip of rocks are more safe and stable compared to those parallel to strike of layers.

In rapid flowage, however, movement of failing mass may be easily visible and mass may travel a few metres or more a day. The conditions causing flowage in two classes may be closely related or entirely different.

Drainage involves removal of water from within mass as well as preventing any furr water reach material susceptible to failure. This may be achieved eir by surface drainage or by subsurface drainage or by both methods.

In rock toppling and falls, wear conditions play a very important role compared to or types of sliding. The precipitation, frost action leads to changes in rocks and lead to rock toppling and falling.