ABSTRACT
Only in rare cases do landslides appear as sudden spontaneous phenomena (landslides caused by earthquakes and liquefaction of quick clays). In the majority of cases landslides represent the final stage of a long preparatory process of creep of slopes preceding the rupture. Surface creep develops in subsurface soils and weathered rocks. Some types of slow movement of earth masses on slopes caused by gravity which may be confused with surface creep are considered briefly, such as, solifluction and formation of accumulative ridges. Depth creep of slopes develop in zones of shear stress concentration attached to a potential surface of rupture. In studies of the creep of slopes it is expedient to express the stress state in terms of mobilized shear strength coefficient which is related to the creep rate of soils. Owing to kinematic restrictions the initial stress state pattern is changed during the creep process and a redistribution of shear stresses in the slope body takes place. Owing to the creep concentration with time, wide creep zones turn gradually into narrow surfaces of rupture.
