Branko Kordić

Characteristics of Pleistocene aeolian – alluvial sediments of the northern coastal cliff of Vrgada island (Adriatic sea, Croatia)

Aeolian-alluvial deposits on the northern part of Vrgada Island were investigated in order to interpret deposition mechanisms and environmental conditions. Preliminary results of basic sedimentological analyses of 49 samples allowed distinguishing 3 facies along the cliff.

DIGITAL MODELLING OF THE LATE ALBIAN SOLARIS DINOSAUR TRACKSITE (ISTRIA, CROATIA)

Abstract: The late Albian Solaris dinosaur tracksite in Istria (Croatia), which is characterized by an abundance of theropod and sauropod footprints, was surveyed using a combination of GNSS georeferencing, terrestrial laser scanning, and photogrammetry. The entire outcrop was digitally captured with millimeter-scale resolution and high spatial accuracy, allowing both outcrop-scale observations and analysis of fine morphological features at the scale of individual footprints. Quantitative ichnological data acquired from the digital model is equivalent to published results based on traditional methods. Inspection of the digital outcrop model has revealed a number of new tridactyl footprints previously undocumented at the Solaris tracksite. All of the newly identified prints are exceptionally shallow and bear characteristics typical of medium-sized bipedal theropod dinosaurs. The study testifies to how approaches involving digital modelling are able to supplement and improve upon traditional methods of field observation and help revise previous ichnological studies. They can be a particularly effective solution for studying complex, heavily trampled tracksites with highly variable print depths and preservation.

Identification of Rock Fall Prone Areas on the Steep Slopes Above the Town of Omiš, Croatia

The aim of this paper was identification of rock fall prone areas above the historical town of Omis, located at the Adriatic coast in Croatia. Unstable areas were identified by kinematic analysis performed based on relative orientations of discontinuities and slope face. Input data was extracted from the surface model created from the high-resolution point cloud. The town of Omis is threatened by rock falls, because of its specific location just at the toe of Mt. Omiska Dinara. Rock fall risk is even higher due to rich cultural and historical heritage of the town. Collection of spatial data was performed by Time of Flight and phase-shift terrestrial laser scanners in order to derivate high resolution point cloud necessary for derivation of surface model. Split-FX software was used to extract discontinuity surfaces were semi-automatically from the point cloud data. Spatial kinematic analysis was performed for each triangle of TIN surface model of the investigated slopes to identify locations of possible instability mechanism. From the results of the spatial kinematic analysis, the most critical parts of the slope have identified for planar and wedge failure and flexural and block toppling. Verification of identified rock fall areas was performed by visual inspection of hazardous blocks at the surface model. Identified rock fall prone areas, unstable blocks and probable instability mechanisms on the steep slopes above the town Omis, present the input data for risk reduction by efficient design of countermeasures.

Object Monitoring in Urban Landslide Areas Using Terrestrial Laser Scanning

Cresnjevec landslide is a reactivated landslide with an unknown precise location, time and cause of initial landslide movement. In the first documents concerning the slopes instability, construction works as well as vegetation removal, were determined to be the causes of landslide activity. Also, future landslide activity was predicted. Landslide remedial works encompassing regulation of the stream in the valley bottom, and construction of drainage wells in the valley, took place in 2004. Despite the remedial works, the landslide remains active and is threatening the houses which are still inhabited. A clear borderline of the landslide can be observed on a digital terrain model created from aerial laser scanning data. Still, due to accuracy limitations of aerial laser scanning, changes in topography cannot be detected to an adequate degree. Data obtained through terrestrial laser scanning (TLS) on the other hand, having millimeter accuracy, is capable of providing satisfactory insight into landslide activity. Thus, object monitoring in the zone of the landslide activity, as well as its vicinity, using TLS was chosen to obtain relevant data. Results of analysis conducted on the gathered data are shown in this paper. The results clearly show this methodologies application capabilities for urban areas facing similar problems.