The large landslide, Kostanjek, on the southern slopes of the mountain
, Zagrebacka Gora, in the western suburb of Zagreb was activated in 19
63 after some 2.1 x 10(6) m(3) of marl for the cement factory, Croatia
, was excavated at the foot of the slope. The geological features (sin
clinal structure, faults, hydrogeological conditions, extension of the
''Tripoli'' marl strata) which had an important role in the formation
of the slide, as well as the means of marl exploitation by means of m
ass blasting, are presented in the paper. The Kostanjek slide involves
an urbanized area of some 100 ha. It is estimated that a sliding mass
of some 32 x 10(6) m(3) is involved, with a maximum depth of 90 m. Sl
iding occurs in three levels. The displacements of the surface are 3-6
m. The excavation of marl was stopped in 1988, when a total of 5.3 x
10(6) m(3) of material was excavated. Since then the magnitude of surf
ace displacement per year has decreased. The Kostanjek slide is still
active. It is estimated that natural stabilization will take a long ti
me, probably decades. Analyses of possible measures for the stabilizat
ion of movements suggested that preventive drainage with continuous ob
servation of the slide is most suitable.