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Besedilo v angl., povzetek v angl. in slov. Soavtorji: Mateja Jemec Auflič, Matija Zupan, Jernej Jež & Tina Peternel. Bibliografija: str. 173-175.

Besedilo v angl., povzetek v angl. in slov. Soavtorji: Ela Šegina, Jernej Jež, Mateja Jemec Auflič, Mitja Janža, Janko Logar, Matjaž Mikoš & Miloš Bavec. Bibliografija: str. 143-147.

In the frame of the Slovenian-Croatian bilateral project SoLiFlyD – Study of landslide in flysch deposits: sliding mechanisms and geotechnical properties for landslide modelling and landslide mitigation we have been investigating geological conditions of landslides in flysch deposits in Slovenia and Croatia. The research area covers Slovenian region of the Vipava valley and the Slovenian coast, and Croatian region of the Istrian Peninsula and the Riječina River Valley. In general, the research area is built in Eocen flysch deposits that are known by geological complexity and lithological heterogeneity. Eocen flysch represents turbiditic succession followed by a regular alternation of sandstones, siltstones and marlstones, and may also include layers of breccias, conglomerates and limestones. As a consequence of active tectonic, geological settings and environmental conditions of research area, flysch deposits are very prone to fast weathering, gradual weakening and decomposition from the ground surface down to the fresh rock, which results in numerous different types of slope mass movements, such as rotational slides, mud flows, as well as rock falls and slumps. The common characteristics of landslides in flysch deposits are the complexity of the sliding phenomena that is connected with the softening of clay-bearing rock layers and that are mostly activated or reactivated by extreme weather events (Petkovšek et al., 2011). In the last decades a large number of landslides have occurred in Slovenia and Croatia in flysch deposits, mostly triggered by prolonged or short intensive rainfall events. According to a national database of landslides provided by Geological Survey of Slovenia more than 80 landslides are registered in the last 15 years (in the time period from 2000 to 2014) only in flysch deposits in Slovenia. The majority of them are smaller earth slides or earth slips but nevertheless the consequences on roads, built structures and other infrastructure were large. One of the largest landslides in Slovenia that were formed in flysch deposits are the Slano Blato landslide (November 2000) and the Stogovci landslide (September 2010). Both landslides were formed on the contact of Mesozoic carbonate rocks and Eocen flysch deposits and were triggered after extreme rainfall event. Furthermore, several studies on landslides on the motorway Razdrto - Podnanos in the Vipava Valley have been done. The Rebernice landslide is known by that scree material deposed on flysch deposits slide downslope as a consequence of inclination, underground water and clayey zones (Jež et al., 2007). According to the landslide database for the Gray Istrian area in Croatia, provided by Faculty of Civil Engineering in Rijeka, 19 landslides that occurred from 1979 until 2010 have been analysed (Dugonjić Jovančević & Arbanas, 2012). Based on field investigations conducted for the purpose of remedial study design, a database of these landslides was created. All documented landslides were mainly caused by heavy rainfall and/or human activity. Generally, they are rotational and translational type landslides, as well as rock falls and debris flow (recorded at one single location). The largest active slope movement along the Croatian coast and in Croatia in general, is the Grohovo landslide which is situated in the central part of the Rječina River Valley. Last reactivation on the north eastern slope of the Rječina River Valley occurred in December 1996 (Benac et al., 2011). In the frame of Slovenian-Croatian collaboration we investigated and compared geological conditions and triggering factors of landslides in flysch deposits in both countries and found some common characteristics as well as differences, that are mainly depends on geological settings and climatic conditions of specific area.