Jan Vlcko

Monitoring of post-failure landslide deformation by the PS-InSAR technique at Lubietova in Central Slovakia

Interferometric synthetic aperture radar data from ERS and ENVISAT sensors were utilized in the analysis of the post-failure deformations in the area of Lubietova town in Central Slovakia. The catastrophic landslide of 1977 together with surrounding landslides in the Lubietova area were analysed with the help of persistent scatterers (PS) technique in order to evaluate recent and past deformations of the unstable slopes. Although long-term precise geodetic monitoring of the 1977 landslide revealed differential deformations inside the sliding mass, due to the lack of the PS located inside the landside caused by temporal decorrelation, unfortunately, these records could not be directly compared. The adjacent landslides with sufficient number of PS were analysed by transformation of the line of sight displacements recorded by the sensors to the slope vector direction. This procedure allowed identification of the precise boundaries of the actively moving landslide parts and the updating of the landslide inventory for the Lubietova area.

Geomorphological Investigations at Machu Picchu, Peru (C101-1)

The landslide hazards analysis was the principal motivation to start geomorphological investigations in the area of Machu Picchu Sanctuary. But very soon, the need of a broader research was revealed, because the landscape evolution of the Urubamba River meander, where the archaeological site is located, is rather complex. Besides slope movements, also deepwards erosion, and selective mass wasting by weathering, suffusion etc. has been active there. Majority of them have been following predisposition by tectonical structure. Large-scale slope deformations have seriously affected mountain morphology in the area. The actual activity of those deformations is not well known yet, inspite that systematic monitoring has provided information as about irreversible movements on open cracks of rock outcrops within the archaeological site up to 1 mmyr-1 (lengths of time series is mostly 3 years), as about movement across the Main Plaza up to 6 mmyr-1. There still are other possibilities to explain those movements by ground deformation due to underground erosion along tectonically shattered zones, or by settlements of heavy stone buildings on water more saturated grounds.

Application of the PS-InSAR Technique for the Post-Failure Landslide Deformation Monitoring at Lubietova Site in Central Slovakia

The interferometric synthetic aperture radar data from ERS and ENVISAT sensors were utilized in the analysis of the post-failure deformations in the area of Lubietova town in Central Slovakia. The catastrophic landslide of 1977 together with surrounding landslides in the Lubietova area were analysed with the help of persistent scatterers (PS) technique in order to evaluate recent and past deformations of the unstable slopes. Although long-term precise geodetic monitoring of the 1977 landslide revealed differential deformations inside the sliding mass, due to the lack of the PS located inside the landside caused by temporal decorrelation, unfortunately these records could not be directly compared. The adjacent landslides with sufficient number of PS were analysed by transformation of the line of sight displacements recorded by the sensors to the slope vector direction. This procedure allowed identification of the precise boundaries of the actively moving landslide parts and the updating of the landslide inventory for the Lubietova area.

Physical Model of the Mechanism for Thermal Wedging Failure in Rocks

Cyclic diurnal and annual temperature variations acting upon rocks are rarely considered among triggers of slope movements. The importance of temperature change is viewed mainly as a precursor of failures, where the triggers are rainfall or seismic activity. This paper aims to determine the limit conditions in which plastic deformation develops in a situation where one or more blocks fallen into an open crack create a wedge, causing non-elastic displacement of a block resting on an inclined plane. A physical model was prepared to study this phenomenon in a thermal dilatometer, in which the displacements were measured using linear variable differential transformer (LVDT) sensors for blocks with different block/wedge ratios, while temperature was varied in a controlled manner. Nine physical models of sandstone blocks were tested over a cyclic temperature change of ΔT = 35 °C while measuring the permanent displacements of a block in order to confirm the existence of this type of failure mechanism. Further, a series of cyclic tests were performed on all nine physical models to determine the threshold temperature change at which plastic deformation occurs for different block/wedge ratios. Results showed plastic deformation resulting from a cyclic wedging mechanism for a block/wedge ratio 0.5 and total model size of 50 mm, reaching a permanent displacement of 4.23 × 10−3 mm for a block resting on an inclined plane with a slope of 7°. For these conditions, a temperature change which caused permanent block displacement by thermal wedging was as low as 6 °C. The results of the physical model are in agreement with a proposed analytical solution by Pasten (2013) and measurements of Bakun-Mazor et al. (2013) at a site at Masada, Israel.

Influence of Thermal Expansion on Slope Displacements (C101-2)

Extremely slow deformations are a frequent phenomenon in the territory of Western Carpathians. These slope movements are in common generated by internal (geological, structural, morphological, geomechanical, hydrogeological, etc.) and external factors (climate factors as temperature, precipitation, air pressure etc.). One of several possibilities how to get more detailed information about kinematics of the rock displacements is monitoring. Within the monitoring records indicating rock slope movement besides real displacements (length/time) climate factors mentioned above are included. In our study, from among several external factors, we tried to estimate the daily temperature fluctuations influence on slope movement - i.e. its kinematics and dynamics as well as on monitoring recording sets. This paper describes the thermally induced influences on the rock mass behavior (expansion, contraction) as well as the possibility of data records filtering and thus to bring representative and essentially correct data into slope activity estimations, geotechnical calculations as well as time prediction for potential failure.

Deformations Dynamics in Response to Seasonal Temperature Oscillations: An Example from Pravcicka Brana Rock Arch (Czech Republic)

The paper discusses the results of the research devoted to the preservation of natural heritage site carried out at Pravcicka Brana Rock Arch located in Bohemian Switzerland National Park, Czech Republic., the largest natural sandstone bridge in Europe. The aim of the study was laid on the relationship between spatial temperature distribution and rate of displacement, as the response to temperature oscillations and to find out kinematic behaviour (deformations dynamics) of the rock arch using computer modeling to simulate if there exists any potential hazard to sandstone body rock arch to collapse.

Rupestrian World Heritage Sites: Instability Investigation and Sustainable Mitigation

Rupestrian settlements were among the first man-made works in the history of humanity. The most relevant masterpieces of such human history have been included in the UNESCO World Heritage List. These sites and their associated remains are not always in equilibrium with the environment. They are continuously impacted and weathered by a variety of internal and external factors, both natural and human-induced, with rapid and/or slow onset. These include major sudden natural hazards, such as earthquakes or extreme meteorological events, but also slow cumulative processes such as the erosion of rocks, compounded by the effects of climate change, as well as the role of humans, especially in conflict situations. Many rupestrian sites have been carved into soft rock, generally with UCS < 25 MPa (ISRM in Int J Rock Mech Min Sci Geomech Abs 18:85–110, 1981), in vertical cliffs, and show major conservation issues in the domain of rock slope stability and rock weathering. This paper reports the experience of rock fall mitigation in rupestrian sites, mainly from the UNESCO World Heritage List (Bamiyan in Afghanistan; Lalibela in Ethiopia; Petra in Jordan, Vardzia in Georgia and others). The general approach, implemented in the activities, includes a very detailed interdisciplinary study, with the objective to understand degradation processes and causative factors, followed, as a subsequent step, by proper field conservation work. The latter is mainly related to re-discovering and potential application of traditional knowledge and sustainable practices, and is primarily based on local conservation techniques.

Kinematic Analysis of a Rock Slope at Strecno Castle (Slovakia) Based on the Processing of the Point Cloud Generated by UAV Photogrammetry

Open image in new window The Strecno Castle (northern Slovakia) stands upon rock cliff formed by Triassic dolomite-limestone rocks which are in overthrusted position. At the toe of the castle rock in relatively narrow area the Vah River, international railway and the primary international road with large volume of traffic is running. Due to extreme morphology formed by almost vertical slopes with several overhangs, lithological composition, tectonic setting and the high degree of weathering, the rock mass is in critical state of stability. Following this situation and having in mind one causality from 2008 when one person in car was killed by the falling rock block, the Ministry of the Environment initiated the programme covering detailed engineering geological investigation including elaboration of kinematic analysis of the rock slope based on the high density point cloud data generated by UAV photogrammetry to delineate potentially unstable parts in the rock slope. The authors describe the procedure of identifying critical structural data sets delineating potentially unstable rock blocks, type of down fall movement and rock fall trajectories. This, along with detailed stability calculation of the critical rock blocks serves as powerful tool to recommend mitigation measures needed to secure the international road and the castle, as well.

Monitoring of the Thermal-Moisture Regime at St. Jacob´s Church in Levoča UNESCO Site, Eastern Slovakia

The paper deals with the monitoring of thermal-moisture regime, as one of the deterioration factors within the rock material at UNESCO historic site, particularly in the supporting pillars of St. Jacobs’s church in Levoca, Eastern Slovakia. The moisture sensor consists of a small cylinder having the diameter and length of 20 mm in which a small ball of 2 mm diameter is placed that delivers the heat in step-wise regime and simultaneously measures temperature. Two sensors have been positioned in South-North orientation and embedded in the church supporting pillars. During monitoring we have identified diffusion of moisture associated with cycle day/night and cycle wetting/drying caused by meteorological precipitation.

Introduction: Landslides in Cultural/Natural Heritage Sites

Multi-disciplinary approach in landslide risk assessment related to preservation of historic and natural heritage sites is the challenge for the future. Presented papers document this fact.