Complex landslide in the Rjecina river valley (Croatia): results and monitoring

This paper presents the results of monitoring of the landslide situated on northeastern slope of the Rječina valley. This is the type of complex retrogressive landslide, starting to develop from toe to head. The slide surface is mainly predisposed by flysch bedrock. The limestone megablock and isolated rocky blocks have also been moved. This is a special phenomenon ; atypical on the flysch slope in the area of Rijeka. The landslide monitoring began in November 1999, after second geotechnical investigations phase. The monitoring consisted of following measurement: groundwater level in 5 borehole piezometres, the deforma-tion in 2 borehole inclinometer, as well as horizontal and vertical shifts on 23 reference points on the land-slide and around it. The magnitude of shifts was very different. The maximum movements were ascertained on upper part, and the minimum shifts on lower part of slope. Horizontal and vertical movements of limestone megablock and isolated blocks are noticeable.