Landslides are downslope movements of rock, debris or earth under the influence of gravity, which may cover a wide range of spatial and temporal scales.

Most landslides occur at steep slopes, but they can also happen in low relief areas in connection with excavations by rivers or construction work. Landslides can be triggered by natural environmental changes or by human activities. Earthquakes, volcanic activity, heavy rainfalls and changes of ground water level are typical natural triggering mechanisms for landslides, which amplify the inherent weakness in rock or soil.

Landslides may result in severe human casualties, property losses and environmental degradation. Therefore, it is well justified that maintaining the stability of slopes is a critical aspect of any geotechnical engineering project. Monitoring the surface displacements of a slope can provide valuable information about the dynamics of the landslide phenomenon. The magnitude, velocity and acceleration of displacements can provide an indication of the stability of the slope. These movements, if detected early enough, can indicate impending catastrophic failure of a slope mass.