The importance of locating the slip surfaces of landslides is emphasized in connection with their investigation and instrumentation, their analysis and their stabilization.
The available methods are divided into two groups, those applicable only to moving landslides and those applicable to stationary ones. The first group comprises inferences from surface movement observations, direct measurements of sub-surface displacements, and geoacoustic sensing. In the second group the methods reviewed include in situ observations from access holes, observations on recovered samples and surface and sub-surface geophysical techniques.
It is concluded that it is advisable to employ a variety of methods and to pursue first the more easily accessible and hence more cheaply gained information. It should also be borne in mind that multiple slip surfaces often exist and that it is important to ensure that the lowest of these is found. An extensive list of references is provided.