Skip to main content
main-content
Top

About this book

This book contains peer-reviewed papers from the Second World Landslide Forum, organised by the International Consortium on Landslides (ICL), that took place in September 2011. The entire material from the conference has been split into seven volumes, this one is the second: 1. Landslide Inventory and Susceptibility and Hazard Zoning, 2. Early Warning, Instrumentation and Monitoring, 3. Spatial Analysis and Modelling, 4. Global Environmental Change, 5. Complex Environment, 6. Risk Assessment, Management and Mitigation, 7. Social and Economic Impact and Policies.

Table of Contents

Frontmatter

Landslide Instrumentation and Monitoring

Frontmatter

New Real-Time Landslide Monitoring System in Polish Carpathians

The first in Poland fully automated real-time landslide monitoring and warning system was implemented in Beskid Niski Mountains. Project was financed by EU funds. Investigated region was characterized by the high landslide risk. A public road, a new bridge, private buildings and important infrastructure were located in risk area. Landslides had difficult engineering geology conditions with active mass movements to the depth of 7–20 m below the natural terrain level. Observed ground movements were varied 5–180 mm in 3 years time. Lithology represented mainly soft clayey soils interbeded by stiff sandstones with shallow groundwater level. Partial stabilization of active landslide area were implemented in the end of 2009. However ground movements of 10–15 mm were observed in some parts of the landslides after that time. They have significantly accelerated in May–June 2010, because of record precipitations and a flood in southern Poland. New instrumentation completed in June 2010. It included three landslide monitoring and one meteorological field stations. Monitoring devices included 3D inclinometers, 60 sensors to the depths of 14–16 m, three uniaxial in-place IP sensors, two automatic VW pore pressure as well as groundwater level and temperature transducers. Meteorological monitoring included automatic monitoring of precipitation, air pressure, air humidity, and air temperature values. All data every hour were transferred into the Internet. It should allow recognizing of landslide processes nature and predict alarm warnings for a public road and a new bridge. Special data interpretation software will help to recognize risk conditions. It will sent early warning SMS messages. Continuous monitoring will be conducted till the end of 2012.

Zbigniew Bednarczyk

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.

Vladimir Greif, Jan Vlcko

Monitoring of the “Razanj” Landslide in Serbia

Serbia is quite known for its conspicuous number of landslides. Unstable slopes with great number of landslides capture very large areas. Detailed engineering-geological investigations of these slides were carried out in the previous period meant for repair works. Unfortunately, the works thereof were carried out within the budgetary constraints, so that the majority of landslides are still active. Highly precise data on the mechanism and depth of sliding processes and cause and effect links of soil water-saturation and landslide activity level have been obtained through long-standing monitoring of landslides.

Svetozar Milenkovic, Branko Jelisavac, Vladeta Vujanic, Milovan Jotic

Terrestrial Laser Scanning for the Montaguto Landslide (Southern Italy)

The evaluation of the landslide surface movements is often difficult because of the inaccessibility of these impervious areas. For this reason, a powerful tool for monitoring is the laser scanning technology (TLS). The landslide monitoring by TLS is complementary to terrestrial SAR interferometry and traditional monitoring techniques. While SAR interferometry is useful for rapid detection of the displacement velocity of monitored points, laser scanning technology also allows the displacement volume quantification (Schwalbe et al. 2008). These analysis provide important information for planning hazard management actions. Experimental surveys were performed for the Montaguto landslide (Campania, Italy), the greatest of Europe, by means of laser scanner Riegl LPM-321 (Alba et al. 2005), with measurement range up to 6,000 m. Differential volume maps from different surveys were obtained. The complex morphology of the Montaguto landslide, located in the Cervaro river valley, had required a viewshed analysis for the selection of the base station locations. Detailed laser scanner acquisitions were conducted on the tip landslide zone, because of the presence of strategic mobility.

Domenico Denora, Lia Romano, Giulia Cecaro

Landsliding Events Triggered by Rainfalls in the Enna Area (South Italy)

The factors affecting slope stability are various, and virtually most are closely interconnected. Among these, meteoric events (or rather, the effects induced by these) are of primary importance, both as predisposing elements, and above all, as triggering factors. Detailed models describing hydrological phenomena at hill-slope scale are complex and expensive. Alternatively, simpler conceptual or empirical models can be used. These models directly correlate rainfall and landslide occurrence and may give satisfactory results both in hazard analysis and real-time forecast. Empirical thresholds are defined collecting rainfall data for landslide meteoric events and for events without landslides. In this paper, the results of a hydrological model correlating the rainfall amount and the landslide occurrences in the Enna area (South Italy) are reported and discussed.

Francesco Castelli, Valentina Lentini

Assessing Volume Earthwork by Using Unconventional Photogrammetry

“Unconventional Photogrammetry” is a measurement methodology which does not require “Camera Calibration” and can use regular consumer camera. The calculation of its “internal and external parameters” is more complicated and less precise than “Traditional Photogrammetry”. But when disaster occurs, Unconventional Photogrammetry can use readily available photos to reconstruct its 3D terrain data very quickly. By comparing this reconstructed terrain data with the terrain data before the disasters, we can quantify the changes in elevation during disasters.

In this paper, we chose a large-scale slope failure event which occurred on the Cidu section of Formosan Freeway on 2010/04/25 at 14:33 and used “Unconventional Photogrammetry” to reconstruct terrain data from two different periods. We estimated that the earthwork volume of the landslide was around 225,078.5 m

3

; and this is close to the result published by Ministry of Transportation and Communications R.O.C. (2010a). It shows that this method is indeed feasible and is able to effectively, economically, rapidly, and quantitatively measure the terrain elevation variations before and after disasters.

Cheng-Yang Hsiao, Pao-Shan Hsieh, Shu-Yeong Chi

The Ancona Early Warning Centre, Instrumentation and Continuous Monitoring of the Landslides

The “Grande frana di Ancona” is a deep-seated landslide inside the city area, reactivated in 1982 after a long period of precipitation. In 2009 Ancona Administration, with a law specifically issued for the people living there, creates an Early Warning System and Emergency Plan; it was developed a surface monitoring system integrated by a subsurface in place geotechnical system

Surface Monitoring System

The combination of different instruments: GPS, Automatic Robotic Stations and tiltmeters sensors allows to monitor a great number of points previously identified.

Geotechnical Monitoring System DMS

In place Geotechnical Monitoring System DMS (patents and trademark CSG-Italy) was installed in February 2009 and is made by no. 3 Modular Dynamic System

Early Warning Management

In Ancona Early Warning Centre a staff controls the monitoring data and alerts the Coordinator in case of emergency.

Stefano Cardellini, Paolo Osimani

Slope Stability Assessment and Monitoring of a Vulnerable Site on Rishikesh-Uttarkashi Highway, India

Landslides are frequently occurring phenomenon in the Himalayas, in the Northern part of India. There were many landslide disasters in the recent past which have taken lives and caused extensive damage to property and public utility services. It is an imperative task to assess the slope instability and evaluate the risk where lives and property are at danger. A vulnerable slope on Rishikesh-Uttarkashi road having few houses, which are under distress, was studied for slope stability assessment. The slope instability was evident by road subsidence and development of cracks in few houses. A comprehensive geological and geotechnical investigation was carried out along with slope movement monitoring. The paper describes the findings of the study.

Shantanu Sarkar, Amitava Ghosh, Debi Prasanna Kanungo, Zamir Ahmad

Landslide Displacement Monitoring from Multi-Temporal Terrestrial Digital Images: Case of the Valoria Landslide Site

This work presents a low-cost method to measure the displacement of some points on the landslide surface. The method uses a sequence of terrestrial digital images. The Image Acquisition System (IAS) consists in a remote connected DSLR camera and controlled by software. The camera is fixed on a stable pillar, inside a transparent box and it periodically takes the pictures of the landslide. In order to rectify the image and to correct the little natural displacement of the image plane with respect to the landslide some fixed reference points are selected in the images. Moreover, some “well recognizable” optical targets are used in order to evaluate the displacement field. The image sequence is analyzed with a home-made digital image correlation code. The colour and size of the optical targets were evaluated in order to get the maximum accuracy of measurements and to improve the auto-matching function between the images. Taking pictures with bracketing function was proved to help the target searching phase for different weather conditions. The possibilities of the method are evaluated with reference to a sequence of images taken at the Valoria landslide site (Northern Apennines, Italy).

Mirco Motta, Fabio Gabrieli, Alessandro Corsini, Vinicio Manzi, Francesco Ronchetti, Simonetta Cola

A Geosensor Network Based Monitoring and Early Warning System for Landslides

In course of the alpEWAS (= alpine Early Warning System) research project a cost-effective landslide monitoring and early warning system has been developed during the last 3 years (2007–2010). The core of the project has been the development and testing of the three innovative, economically and continuously working measurement systems time domain reflectometry (TDR) for the detection of subsurface displacements in boreholes and reflectorless video tacheometry (VTPS) and a low cost GNSS sensor component for the determination of 3D surface movements. These measurements systems are combined together with other systems, monitoring trigger factors such as precipitation, in a geo sensor network which can be accessed remotely by a web interface, thus enabling to access all data in near real time. The Aggenalm Landslide (Bavarian Alps in the vicinity of Bayrischzell) was chosen as a field laboratory for the alpEWAS project. For 2 years now, the system has been working continuously except for minor disruptions, acquiring and recording all data.

Kurosch Thuro, John Singer, Judith Festl

Underground Landslide Displacement Monitoring: A New MMES Based Device

This paper describes the analysis of the effectiveness and reliability of a new type of inclinometric chain, which is still under development by the authors, and is intended to be applied in the underground slope monitoring field. In the first part, the paper describes the new instrumentation which should allow for a deeper and detailed understanding of the type, location and origin of slope movements that should, in turn, help in understanding the triggering causes and the evolution mechanisms of landslides, and provide an innovative and substantial contribution to their stability analysis and control. The second portion of the paper is dedicated to a comparison between the classic instruments and the new MUMS device, demonstrating the advantages of measurement automation and economy in the use of the proposed device, which could also be equipped with other electronic instruments that would allow the measurement of other interesting physical quantities (such as pore pressure, temperature, stresses, etc.) together with displacement components.

Andrea Segalini, Corrado Carini

Groundwater Investigations Using Optical and Microwave Remote Sensing Data in Solani Watershed, India

This article describes general hydrogeological set for the Solani watershed. Satellite imagery obtained from Landsat-7 ETM+ has been analysed to prepare the groundwater prospects map. By using SAR interferometry techniques, paleochannels, geomorphic units, lineaments, could be identified and delineated at a reasonable level of accuracy. In this study the following aspects have been covered: drainage map, geology, geomorphology, depth of water table map, water table contour map, EC (electric conductivity) distribution map etc. From these thematic maps ground water prospects map, has been prepared. As seen in these maps, the depth of water table in this area ranges from 2 m from ground level to more than 100 m; the EC of ground water varies from 284 to 2,000 μS/cm. Five different prospect zones: excellent, good, moderate, low, and runoff zone are identified according to the integration of thematic maps.

Amed Bennia, S. K. Srivastav, R. S. Chatterjee

Application of a Multiplet-Location Coupled Technique to Microseismic Data for Identification of Rock Slope Active Surfaces

In rock slope analysis, formation and growth of microcracks are usually coupled with the propagation of elastic waves that can be detected by a suitable microseismic monitoring system. The correct analysis and interpretation of the recorded activity can provide information on the size and the type of the rupture mechanisms. A combination of the coherency computation and the source location techniques, typically used in seismic signal processing, is here proposed to this aim. The application to a microseismic dataset recorded by the microseismic monitoring system installed on the Matterhorn Peak, has evidenced the effectiveness of this approach. In particular the coherency has allowed to identify a set of similar appearing events, while the location of the corresponding hypocenters has evidenced the alignment of the sources on a planar surface, whose orientation is closed to the orientation of a discontinuity system resulting from a morphostructural survey.

Cristina Occhiena, Marina Pirulli, Claudio Scavia

Slope Disaster Monitoring System Using Battery-Operated Wireless Sensor Network

This paper develops a slope disaster monitoring system using distributed sensors. The sensor node has wireless communication and tilt detection capabilities. Each sensor node communicates to each other and sends the corrected data to a base station, which can send an alert message to administrators in case of emergency. The developed slope disaster monitoring system is installed on a slope along the Chugoku Expressway. This first experimental study showed a significant potential of the developed distributed sensor network for detecting slope failures, but it also clarify that the wireless communication capability is sensibly influenced by relative geometric alignments of each sensor nodes. The second experimental study has begun along the Maiduru-Wakasa expressway. Since the geometric alignments are modified, we are having an improved wireless communication correspondence.

Keigo Koizumi, Kenji Hirata, Kazuhiro Oda, Yukishige Fujita, Sadayuki Kamide

The Use of ERT for Investigation of Berzhita Landslide, Tirana Area, Albania

In this paper we present an engineering geological-geophysical investigation of the Berzhita landslide, Tirana area, Albania. The work includes engineering-geological field investigation and geophysical measurements. A detailed field investigation was conducted to delineate the aerial extent and a general direction of movement of the landslide zone, assess lithological section, estimate the thickness of the sliding layer, and delineate water saturated zones. In order to study in detail this landslide, two perpendicular Electrical Resistance Tomography (ERT) profiles were carried out. A detailed engineering-geological study was conducted including, engineering mapping on scale 1:100, geotechnical investigations such as drilling and trial pits at 14 points with depths 3–4 m, soil sampling and laboratory tests for geotechnical parameter studies. The results of field investigations are presented as engineering geological map and several geological and resistivity images cross-sections which clarify the geometry and subsurface characteristics of the landslide.

Hamza Reci, Ylber Muceku, Idriz Jata

Conventional and Innovative Techniques for the Monitoring of Displacements in Landslide Affected Area

This work shows a methodological approach for the joint use of geological and geomorphological studies and conventional/innovative monitoring data in densely urbanized areas at landslide risk. The methodology is applied to a test area in the Calabria region (southern Italy) extensively affected by several active landslides involving urban areas. These landslides have been studied and monitored via ground-based techniques for many years. In the study area the comparison and interpretation of DInSAR data with geomorphological studies and inclinometric monitoring has been carried out. The results obtained, thanks to the validation of remote sensed data via ground-truths, provide a further step towards the integrated use of DInSAR data within landslide risk mitigation strategies.

Loredana Antronico, Luigi Borrelli, Dario Peduto, Gianfranco Fornaro, Giovanni Gullà, Luca Paglia, Giovanni Zeni

Spatio-Temporal Evolution of Ground Displacement of the Tena Landslide (Spain)

The scope of the DO-SMS program is dedicated to the ground displacement observation. We present here our results for the Tena landslide (Spain). By combining geotechnical and remote sensing tools precise ground displacement maps were established. Using the multi-temporal photographs optical correlation was performed. Correlation is used for quantifying the north/east components of ground displacement of the area and the last component was calculated by using Permanent Scatterers. These results point out a new landslide history. An initial period (1994–2003) in which the upper part of the debris avalanches flowed westward. The second period commenced with the construction in 2004 of a car park and is marked by the deviation of the landslide downward to this car park. Geotechnical/geophysical data enable us to identify the principal rupture plane at ~40 m of depth. The analysis of the temporal series indicates non-linear displacement rates generally correlated with rainfall events and/or seasonal variations.

Nguyen Anh Tuan, Saillard Marianne, Darrozes José, Oliver Marc, Herrera Garcia Gerardo, Garcia Lopez-Davalillo Joan Carlos, Gonzalez Nicieza Celestino, Álvarez Fernández Inmaculada, Monod Bernard, Mulas De Peña Joaquim, Soula Jean-Claude, Guerrero Nicole, Courjaul-Radé Pierre

Long-Term Analysis of Landslides Via SBAS-DInSAR Technique

Advanced techniques of multi-pass space-borne Differential Synthetic Aperture Radar (SAR) Interferometry (DInSAR) represent a valuable tool in landslide studies allowing to remotely investigate the behavior of mass movements on long time intervals by benefiting of large datasets of SAR images covering the same area and acquired at different epochs. Among these techniques, we apply the Small BAseline Subset (SBAS) approach for analyzing surface deformation at two spatial scales, i.e., regional and local scale.

In this work, developed within the framework of the DORIS FP7-EU project, we investigate mass movements occurred in the Umbria region (central Italy) during the last 20 years, by exploiting ERS-1/2 and ENVISAT SAR images spanning the 1992–2010 time interval. Our two-scale SBAS analysis allowed detecting active landslides over all the study area, and further giving more insights on the spatial and temporal pattern of localized phenomena.

Manuela Bonano, Fabiana Calò, Michele Manunta, Luca Paglia, Giovanni Zeni

4D Monitoring of Active Landslides by Multi-Temporal Airborne LiDAR Data

We present results of a multi-temporal analysis of airborne LiDAR data collected between 2006 and 2010 on the 3 km long active Montaguto landslide (Italy). Digital Terrain Models are constructed from data acquired on May 2006, July 2009, April 2010 and June 2010. The spatial distribution of selected morphometric parameters and the statistical analysis of the temporal variations of such parameters allow us to reconstruct the evolution of the landslide. We recognize zones of uplift and subsidence, estimate the volumes of removed or accumulated material, and determine the average rate of vertical and horizontal displacement. We also map the deformations structures and provide new insights on the sliding mechanisms. Zones in which the topographic features change due to handling/removal work are also analyzed. The approach proposed here provides new insight on the use of airborne LiDAR in the surveillance strategies of landslides and other gravity-controlled processes.

Guido Ventura, Giuseppe Vilardo, Carlo Terranova, Eliana Bellucci Sessa

Experiences of Debris-Flow Monitoring and Warning at Catchment Scale in the Pyrenees

Debris-flow monitoring improves the understandings of debris flows and also provides fundamental information for an efficient early warning and alarm system (EWAS), which commonly focuses on ground vibration and flow depth. Preliminary results from the Senet station (Central Pyrenees, Spain) show that monitoring is a complex task, especially if different torrential processes should be distinguished using merely geophone data. Video images are not useful for an EWAS, but strongly improves the analysis, because they allow to identify the flow type and to characterise the ground vibrations corresponding to each type. In addition, an EWAS can also be based on triggering rainfall patterns, which have to be defined by a one-parameter o multi-parameter condition. Our first experiences on the possible implementation of an EWAS at Senet test site are promising, but indicate the complexity regarding the critical rainfall conditions, the definition of reliable thresholds to avoid false alarms and the difficulties related to technical shortcomings.

Marcel Hürlimann, Claudia Abancó, Jose Moya

Setup of a Landslide Monitoring System on the Philippine Island of Leyte Near the Village of Malinao (Municipality of St. Bernard)

This article describes the setup and first results of a landslide monitoring system near the village of Malinao, municipality of St. Bernard on the Philippine Island of Leyte. The monitoring system combines wireless sensor network (WSN) technology with low-cost but precise micro sensors (MEMS). The system was developed in the framework of the joint project “SLEWS—A Sensor-based Landslide Early Warning System” that deals with the development of a prototype Alarm- and Early Warning System (EWS) for different types of landslides. The sensors integrated in the WSN are acceleration sensors, tilt sensors and barometric pressure sensors. The system was installed in November 2010 in a landslide prone area near the village of Malinao. For longer data transmission of about 15 km the SLEWS-System was combined with the already existing WLAN-based monitoring system for Flood Early Warning (FEWS) from the

Deutsche Gesellschaft für Internationale Zusammenarbeit

(GIZ).

Christian Arnhardt, Olaf Neussner

Application of the Newly Frequency Domain Electromagnetic Method Survey in a Landslide Area

Geophysical survey in a Landslide area is mainly perfomred by measuring the elastic wave velocity or electric resistivity. The electrical resistivity is well known to reflect the information in a slope, which can be obtained by the seismic prospecting or electrical resistivity survey. The commonly used electrical resistivity survey has disadvantage sometimes due to local ground conditions during the installation of electrodes and layout of electric cables on the hard material. On the other hand, the frequency domain electromagnetic method (FDEM), one of the electromagnetic methods, has advantages due to its nondestructive measurement nature and also its simple operation. In this study, we used a newly developed FDEM survey apparatus to examine its applicability in the exploration of landslide. The results showed good consistency with the structure of the landslide mass, which had been indentified by many other apporaches during the passing decades. Therefore, we concluded that FDEM is an effective method in exploring the area and also the inner structure of landsliding mass.

Gen Furuya, Tatsuo Katayama, Akira Suemine, Takayuki Kozato, Takahiro Watanabe, Hideaki Marui

Characterization and Study of a Complex Landslide Site in Northern Italy

The present paper deals with a diffused and continuous kinematic phenomenon in Liguria (Italy). In order to study this complex and wide landslide many data have been collected in a unique platform in GIS (Geographic Information System) obtaining a 3D model of a large area, whose morphology and features are variable. The platform integrates hydrological and geotechnical data and allows stability analyses.

Roberto Passalacqua, Rossella Bovolenta

HR Satellite Imaging and Borehole Monitoring of Landslides in Daunia, Italy

We examine the instability of slopes in a catchment traversed by a 11 km long mid-slope road, characterized by the widespread presence of clay materials with poor geotechnical properties. High Resolution (HR) multispectral satellite imagery is used to provide focus on the landslides affecting the road and on their close association with poorly drained sites (wet areas, concentration of roadway runoff). The origin of many wet areas mapped from the satellite imagery is linked to the seasonally persistent high groundwater levels revealed through the piezometer monitoring. The remotely sensed data integrated with the in situ controls and subsurface monitoring show that the slopes traversed by the road are poorly drained and marginally stable. Thus even relatively moderate rainfall events (e.g. several tens of mm of rain in few days) can lead to landslide re-activations, which typically occur in the second half of fall and winter periods characterized by higher groundwater levels.

Janusz Wasowski, Caterina Lamanna, Giuseppe Gigante, Domenico Casarano, Pier Paolo Limoni

Monitoring Concepts and Requirements for Large Rockslides in Norway

The risk due to large rockslides in Norway is due to large run-out, the possibilities for river damming and the generation of disastrous tsunamis in fjords. The investigations, monitoring and early-warning that have been designed and implemented for the Norwegian rockslides follows requirements guided in national codes and international standards for geotechnical design. The investigation program is composed of the following main parts: (1) Surface investigations; (2) Ground (subsurface) investigations; (3) Analysis and modeling; (4) Evaluation of physical mitigation; and (5) Documentation. The design and implementation of monitoring systems follows the following main concepts: (1) Sensors on the surface and in boreholes that gives sufficiently knowledge about movements; (2) Sensors giving information about controlling mechanisms for movements (Meteorological station and water pressure); and (3) Backup systems for all critical sectors by establishing different types of monitoring systems. The infrastructure including power-supply system and data communication from the site is designed to fulfill the demand of redundancy. Based on the historical data and information from historical rockslide events elsewhere, early-warning levels have been implemented in the operational system.

Las Harald Blikra, Lene Kristensen

Continuous Monitoring and Near-Real Time Processing of GPS Observations for Landslide Analysis: A Methodological Framework

The objective of this work is to present a methodology for the near-real time characterization of displacements using permanent GPS stations on landslides. In France, several GPS receivers have been installed on active landslides since a few years. These landslides show very different displacement rates and kinematic regimes. For the monitoring of landslides where the required degree of accuracy is millimetric, GPS has been mainly used for repeated measurements, as a complement to conventional geodetic methods. Permanent monitoring is still not usually performed operationally.

Jean-Philippe Malet, Patrice Ulrich, Aline Déprez, Frédéric Masson, Candide Lissak, Olivier Maquaire

Retrogressive Slope Failures in Natural Slope: A Case Study

A study has been carried out to investigate a slope in a granitic formation, that has been slowly but constantly moving since a small part near the toe of the natural slope was regraded in 1986 to make way for a road construction. Many scars on the slope surface suggest retrogressive failures have taken place. Investigation has been carried out to identify the causes and the extent of the failures so that an effective solution can be found. Site investigation with the geophysical procedures data shows the relatively shallow water table. Correlation between the pore pressure build up in the slope with the slope movements indicates that initiation of movement occurs quite consistently at a certain ground water level. The data gathered will be used to provide effective solutions to the slope movements and predict the quantum of the movements.

Che Hassandi Abdullah, Ghazali Hussin

Performance of Image Correlation Techniques for Landslide Displacement Monitoring

The objective of this work is to present the applicability of image correlation techniques (applied to very-high resolution terrestrial optical photographs and to very dense Terrestrial Laser Scanning (TLS) point clouds) to monitor the displacement of continuously active landslides. The method has been developed to characterize the kinematics of very active landslides with cumulated displacement of several decimeters per year. The data are processed with a cross-correlation algorithm applied on the full resolution images (photographs and DEMs produced from the TLS data) in the acquisition geometry. Then, the calculated 2D displacement field is ortho-rectified with a back projection technique. The method allows to characterize the heterogeneous displacement field of the landslide in time and space, and to produce displacement maps. The performance of the technique is assessed using as reference differential GPS surveys of a series of benchmarks.

The sources of error affecting the results are discussed. Because the proposed methodology can be routinely and automatically applied, it offers promising perspectives for operational applications like, for instance, in early warning systems.

Julien Travelletti, Christophe Delacourt, Jean-Philippe Malet, Pascal Allemand, Jean Schmittbuhl, Renaud Toussaint

A Novel Fiber Optic Sensing System for Monitoring Debris Flows

This study presents a novel fiber optic sensing system for monitoring debris flows. Thanks to their light weight, immunity to electromagnetic interference, high sensitivity, and very low optical loss, fiber optic sensors can be potentially utilized to monitor debris flows, which usually occur in mountainous regions far from available electricity. The ground vibrations caused by debris flows can be sensed by a Fiber Bragg Grating (FBG) Accelerometer (Gavea Sensor GS 6500) and the associated light source, and data logger are provided by a Braggscope (Fiber Sensing FS 5500). Four FBG Accelerometers were deployed along the Ai-Yu-Zi Creek and the Chu-Shui Creek in Nan-Tou County, Taiwan, respectively; and the Braggscope was located at the front data-receiving center. The calibration experiment was carried out to compare the performance of FBG accelerometer with other sensors used for detecting debris flows, such as geophone and microphone. The signal-to-noise ratio (SNR) of FBG accelerometer was higher than that of geophone, while the two instruments sensed the same vibration source. The results showed that fiber optic sensing technique could be used as an alternative for monitoring debris flows.

Chung-Ray Chu, Ching-Jer Huang, Tsung-Mo Tien

Integrated Monitoring of Lateral Spreading Phenomena Along the North-West Coast of the Island of Malta

Landslides, and especially lateral spreading, are responsible for the main landforms observable along the north-western coast of the Island of Malta. A series of rock spreading phenomena, and associated mass movements, have been recognised in this area and the most significant cases have been investigated by means of a multi-technical approach which envisaged geomorphological survey and mapping, geophysical analyses and monitoring of displacements. The aim of the study was to define whether rock spreading phenomena are active along the investigated coastal stretch and, possibly, to determine the rate of movement of the most relevant cases. In this framework, a multidisciplinary approach was used and different techniques were tested and applied on a specific site, which was selected for the presence of an extensive rock spread phenomenon which may induce hazard conditions. The site is located at Il-Prajjet (Anchor Bay), a narrow inlet where a tourist attraction is located. Research activities have been carried out at Il-Prajjet since 2006 when a GPS network of eight benchmarks was installed. This technique was chosen because it proved to be a powerful tool in the study of similar ground deformation in coastal and mountain areas, showing high accuracy and reliability. Once GPS monitoring had showed that rock spreading was active, further techniques were applied in order to achieve an in-depth knowledge of the instability processes occurring at Il-Prajjet. The paper illustrates the results so far achieved thanks to GPS monitoring, tape extensometer measurements, SAR interferometric analyses and GPR investigations.

Stefano Devoto, Emanuele Forte, Matteo Mantovani, Arianna Mocnik, Alessandro Pasuto, Daniela Piacentini, Mauro Soldati

InSAR Data for Mapping and Monitoring Landslides in Tena Valley

In the last 20 years the exploitation of satellite SAR interferometry has shown a considerable improvement due to the development of new InSAR PSI techniques and the availability of the new satellite sensors with higher spatial and temporal resolution. One of the most interesting applications is the possibility of mapping slow landslides processes. In this paper we present an analysis of the advantages and disadvantages of using L-, C- and X-band sensors for mapping and monitoring landslides in the Rio Gállego upper basin (Central Pyrenees, Spain) techniques.

Juan-Carlos García-Davalillo, Gerardo Herrera, Davide Notti, Mario Hernández-Ruiz, Jose-Antonio Fernández-Merodo, Inmaculada Álvarez-Fernández, Celestino González-Nicieza, Tazio Strozzi, Oscar Mora

Monitoring Displacement on the Mannen Rockslide in Western Norway

In Norway, four large rock slides are considered high-risk objects and equipped with real time early warning system. The mountain Mannen is the most recently instrumented of those. Construction and instrumentation was started in 2009 and was almost completed in 2010. To ensure redundancy, several types of instruments are used, such as lasers, realtime DGPS, extensometers, ground based InSAR system, borehole instrumentation and a meteorological station. The surface displacement is about 3 cm/year, with the largest velocity in the upper part, where the annual probability of failure estimated to 1/100. Strong subsurface deformation is measured in a 120 m borehole, suggesting a complex movement in a graben structure at the back-crack.

Lene Kristensen, Lars Harald Blikra

Multitemporal Study of the San Martino Sulla Marrucina Landslide (Central Italy)

In this study, we aim at achieving details on the San Martino Sulla Marrucina (SM) landslide failure mechanisms. The SM landslide represents one of the most complex and large-scale mass movements recently occurred in the Chieti province (Central Italy). We present the preliminary results of an integrated study based on a multidisciplinary approach. The investigated phenomenon represents a local reactivation of a wider quiescent landslide and that its morphological evolution is doubtless characterized by a retrogressive trend. Furthermore, we propose a geodynamic model based on deep kinematic conditioning. The data collected, integrated with those already existent, will permit further investigations of the landslide susceptibility in the municipality territory and in the surrounding areas.

Elisa Damiano, Daniele Giordan, Paolo Allasia, Marco Baldo, Nicola Sciarra, Giorgio Lollino

Surface and Deep Displacements Evaluated by GPS and Inclinometers in a Clayey Slope

The continuous deformations of two landslides of a clayey slope of the Italian Southern Apennines cause damage to buildings and infrastructures. In 2004, 11 inclinometer casings were installed to monitor them. In 2006, fixed-in-place probes with continuous data acquisition were installed in two of those casings, in correspondence to the detected slip surfaces. In 2010, such probes went out of use, thus were removed and periodical measurements restarted. The validity of the interpretation of previous localized measurements could thus be ascertained.

In 2006, GPS permanent and non-permanent stations had also been installed. By taking into account a possible mechanism of interaction soil-GPS station, displacements very close to those obtained by nearby inclinometers with fixed casing tip are obtained.

Depending on its particular properties, one of the landslides undergoes uniform displacements in each transversal section of the channel. So, GPS data can also give useful information on the movement of the whole section.

Caterina Di Maio, Roberto Vassallo, Margherita Vallario, Stefano Calcaterra, Piera Gambino

A Possible Mechanism of Movement of an Ancient Clayey Landslide

The displacement rate of the considered ancient clayey earth slide varies noticeably along its longitudinal axis, however it is practically constant from the slip surface to the ground along four inclinometer profiles. In this paper, the displacement uniformity and the absence of viscous deformation are discussed and justified. The comparison among the theoretical shear stress distribution—within the landslide body and on the slip surface—the experimental peak shear strength and the residual shear strength shows that shear stresses are lower than or equal to residual strength. This latter, in turn, is much lower than the peak strength. Furthermore, long term shear tests carried out under controlled shear forces suggest that only primary creep occurs at shear stresses lower than residual strength. So, the landslide displacements can be hypothesized uniform in each entire transversal section of the channel.

Roberto Vassallo, Caterina Di Maio, Margherita Vallario

Results of Geoelectrical Monitoring of Landslides Collected by the SafeLand/TEMPEL Network

Based on the promising results from a pilot monitoring project the GEOMON4D geoelectrical monitoring system was applied to several landslide monitoring tests sites, where also permanent monitoring data of displacement and hydrology are available to investigate the correlation of electrical parameters with other data. This monitoring network was set up in frame of the FP7 project SafeLand and the project TEMPEL (Austrian Science Fund) starting from October 2009 on. Analysis of the first monitoring results confirmed the potential of geoelectrical parameters as additional indicators to be applied within future early warning systems of landslides.

Robert Supper, Birgit Jochum, Ivo Baroň, Alexander Römer, Mario Lovisolo, David Ottowitz, Stefano Cardellini

Geophysical-Geotechnical Sensor Networks for Landslide Monitoring

In this study we describe the development of an integrated geophysical/geotechnical sensor network for monitoring an active inland landslide near Malton, North Yorkshire, UK. The network is based around an automated time-lapse electrical resistivity tomography (ALERT) monitoring system, which has been expanded to incorporate geotechnical sensor arrays. The system can be interrogated remotely using wireless telemetry to enable the near-real-time measurement of geoelectric, geotechnical and hydrologic properties.

The overarching objective of the research is to develop a 4D landslide monitoring system that can characterise the subsurface structure of the landslide, detect changes in the slope, and reveal the hydraulic precursors to movement. Results to-date have shown that ALERT can characterise 3D landslide features, and detect changes associated seasonal temperature and subsurface moisture content changes, and crucially, the displacement of geophysical sensor arrays that allows the motion of the landslide to be monitored in near-real-time.

Jonathan Chambers, Philip Meldrum, David Gunn, Paul Wilkinson, Andrew Merritt, William Murphy, Jared West, Oliver Kuras, Edward Haslam, Peter Hobbs, Catherine Pennington, Chris Munro

Remedial Works on the Smrečje Landslide, Croatia

The Smrečje Landslide was occurred on the county road near the Gerovo village in Gorski Kotar region, Croatia, before more than 10 years. The landslide location is forming in clastic formations of shale, sandstone and marl rock masses from Triassic age. The landslide was overtaken 100 m long part of the road construction. The instability was evidenced in long term creep process with deformation increments associated with the seasonal water content variations in the clayey superficial deposit. Deformations on the pavement construction were reaching unacceptable values during 2008 that caused necessity of complete landslide remediation. Field investigations were executed and the remediation measures were designed. Field investigations were included investigation drilling, soil and rock mass samples taken, geophysical measurements using seismic refraction and geoelectrical tomography techniques so as engineering geological surface mapping. In the paper we will present description of the Smrečje landslide, results of the conducted field investigations, so as designed remediation measures. Based on the remediation design, the remediation works were constructed in the spring 2009.

Željko Arbanas, Vedrana Galijašević, Petra Đomlija, Martina Vivoda

Monitoring Slow-Moving Landslides Using Spatially Adaptive Least Squares Image Matching

This study presents and evaluates an algorithm which uses the least squares image matching (LSM) with spatially adaptive and high-order geometric models to estimate horizontal surface displacements of slow-moving landslides from repeat optical images. Pairs of high resolution optical images over a rockglacier creep and a slow-moving landslide are orthorectified and co-registered. Image matching is applied first using the conventional normalised cross-correlation (NCC), then using the LSM algorithm with image-wide single geometric models, and finally using the LSM with spatially adaptive geometric models. The spatially adaptive algorithm operates in such a way that for each template the model that produces the lowest sum of square of intensity difference is considered the best fitting model. Affine, projective and second-degree polynomial geometric models are included. The algorithms are evaluated in reference to the NCC algorithm based on the signal-to-noise ratio of reconstructing the reference image from the search image.

Misganu Debella-Gilo, Andreas Kääb

Seismometric Monitoring of Hypogeous Failures Due to Slope Deformations

Results from a seismometric monitoring of rock mass failures affecting a karstified slope are here presented. The slope, located in Central Apennines (Italy), hosts a drainage plant and is involved in gravity-induced deformations.

Starting from September 4, 2008 four accelerometric stations were installed within the tunnels of the drainage plant.

More than 1,000 events, referred to both earthquakes and hypogeous rock mass failures, were recorded.

The frequencies of occurrence of earthquakes and rock mass failures result to be generally well correlated; nevertheless, many hypogeous instabilities can be directly associated to the continuous slope deformations.

The trend of the cumulative Arias intensity derived for the hypogeous instabilities shows a time variable rate which was used as a tool for monitoring the deformational process of the slope as well as for managing the associated geological risk by the use of alert or alarm plans.

Luca Lenti, Salvatore Martino, Antonella Paciello, Alberto Prestininzi, Stefano Rivellino

Use of Persistent Scatterer InSAR within Terrafirma Landslide Services

Landslide Services of the pan-European project Terrafirma are presented. LandSlide Inventory (LSI) and LandSlide Monitoring (LSM) exploit satellite Persistent Scatterer InSAR (Synthetic Aperture Radar Interferometry) to monitor extremely to very slow moving landslides at both regional and local scale. Validated case studies of LSI in the Upper Tena Valley (Central Pyrenees, Spain) and LSM in Val Lumnez (Switzerland) are described. 14 TerraSAR-X descending images acquired in May–October 2008 are processed with the Stable Point Network (SPN) technique, and used to update the landslide inventory of the Upper Tena Valley, significantly improving the pre-existing landslide mapping. 68 ERS1/2 and ENVISAT ascending scenes, acquired in May 1992–October 2005 and processed with the Interferometric Point Target Analysis (IPTA) technique, are combined with topographic levelling measurements performed in 1887–1992, and exploited to monitor the Val Lumnez landslide and to improve the geomorphologic zonation.

Sandro Moretti, Francesca Cigna, Federico Raspini, Geraint Cooksley, Marie-Josée Banwell, Hugo Raetzo, Gerardo Herrera, Davide Notti, Juan Carlos García Davalillo

Detection and Characterization of Rock Slope Instabilities Using a Portable Radar Interferometer (GPRI)

A portable radar interferomter was used to periodically monitor a rock wall, where millimeter-scale displacements (0.5–0.6mm/month) on an unstable rock slab were detected. Preliminary interpretation of a radar images acquired over a 5 month period revealed evidence for combined toppling and buckling failure mechanisms on the rock slab. The rock wall of interest has a history of block fall activity, which directly endangers a roadway in Canton Graubünden, Switzerland.

Andrew Kos, Tazio Strozzi, Reto Stockmann, Andreas Wiesmann, Charles Werner

Landslides and Hydro-Climatic Conditions in the Hutná Catchment Area (Central Slovakia)

This contribution presents preliminary results obtained by hydro-climatic analysis of the Hutná catchment area in Central Slovakia, where several landslide reactivations were recorded in last decades as a consequence of weather anomalies. The majority of these landslides reach the inhabited areas, thus continuously threatening individuals who live there. We have been focused on evaluation of hydro-climatic conditions that preceded the reactivation events to better understand relationships between precipitation, antecedent hydrological conditions of the catchment and initiation (or reactivation) of movements. Our analysis confirms that antecedent hydrological conditions can be crucial for failure initiation in slopes with thick colluvial deposits. While the rainy seasons following a long-lasting wet periods were responsible for failure initiations and/or landslide reactivations, only slight acceleration of creep movements were recorded after the rainy seasons (although exceptional and several moths long) following dry period.

Roberta Prokešová, Alžbeta Medveďová, Zora Snopková

Landslide Umka: The First Automated Monitoring Project in Serbia

In the past decade, there has been a gradual introduction of systematic monitoring on the largest landslides in Serbia by establishing a network of monitoring facilities. The first manual monitoring system was installed near Belgrade on Umka landslide including survey points, inclinometers, piezometers, triaxial deformeters etc. As the rapid adoption of new technologies continues – the natural evolution of equipment for landslide monitoring has started. The technological evolution of GPS based systems creates the potential for automated remote collection of accurate, high resolution data and represents step forward that will increase speed, precision, cost effectiveness and overall quality of landslide investigations. This paper presents first results, features and benefits of introducing automated approach in order to provide high quality data as a base for detailed landslide investigations.

Biljana Abolmasov, Svetozar Milenković, Branko Jelisavac, Vladeta Vujanić

Landslide-Related PS Data Interpretation by Means of Different Techniques

Two different techniques aimed at assessing deformation data related to slow-moving landslides are here discussed, both being based upon Persistent Scatterer Interferometry. To this scope, a case-study from Calitri, Campania region, Italy is dealt with, represented by a large complex landslide re-activated by the 23 November 1980 M=6.9 earthquake. Through the first technique, ascending and descending geometry dataset have been used, creating synthetic PS and vertical and easting displacement maps. The second procedure consisted in a morphometric decomposition of the velocity vector for each PS with respect to the maximum downhill slope angle and slope aspect. The results from both techniques were finally compared and discussed.

Diego Di Martire, Gabriele De Luca, Massimo Ramondini, Domenico Calcaterra

Advanced Image Analysis for Automated Mapping of Landslide Surface Fissures

Surface fissures are potential indicators of slope instabilities and considerably influence infiltration characteristics of the soil. The increasing availability of unmanned aerial vehicles (UAVs) enables the observation of surface features at unprecedented detail and this study develops an image processing method combining Gaussian filters and object-oriented image analysis to map such features in very-high resolution (VHR) aerial images largely automatically. At three different time steps the results of the technique are compared with expert elaborated maps.

A. Stumpf, U. Niethhammer, S. Rothmund, A. Mathieu, J. P. Malet, N. Kerle, M. Joswig

Portable Ring Shear Apparatus and Its Application

The paper presents the concept, design and construction of new ring shear apparatus, ICL-1. The new apparatus is, compared to previous ones (DPRI-5, 6, 7), much smaller in dimensions and has higher performances. It can keep undrained condition up to 1 MPa of pore water pressure (up to two times more than in previous versions of apparatus) and load normal stress up to 1 MPa. This makes it suitable for investigation of large- scale and deep seated landslides. Speed control test and undrained cyclic loading tests were performed to show experimental procedures in details. Typical test results are presented to show the efficiency of this ring shear apparatus.

Maja Ostric, Kyoji Sassa, Bin He, Kaoru Takara, Yosuke Yamashiki

Assessing of Spatio-Temporal Factors Influencing Landslides Using PSInSAR

The need of living together with landslides in a sustainable way requires a strong effort in terms of landslide analysis. Traditional methods used for mapping and monitoring mass movements can benefit from the application of remote sensing techniques coupled with GIS analysis. The use of remote sensing technologies, whether air, satellite or ground based allows a rapid acquisition of quantitative data over wide areas, reducing the field work and, as a consequence, the costs. A modern satellite radar interferometry method of Permanent scatters (PSInSAR) is very useful. At Geological Survey of Slovenia, the PSInSAR

TM

data were used to assess spatio-temporal factors which influence on slope mass movements and small, long lasting ground deformations were defined in the Škofjeloško Cerkljansko area during the years 1992–2000.

Mateja Jemec Auflič, Magda Čarman, Marko Komac

Methodological and Technological Advances in the Application of Spaceborne DInSAR for Landslide Monitoring

Differential Interferometry Synthetic Aperture Radar is a mature remote sensing technique broadly used for the measurement of slow deformations with major application in several fields. In the last years, the application to slow moving landslides has grown quickly and several examples of the monitoring capability can be found in the literature. Main goal of this work is the description of the advances in terms of products that can be achieved from both an innovative methodological approach to DInSAR data analysis and the technological improvements related to the last generation of sensors.

G. Fornaro, D. O. Nitti, R. Nutricato, F. Bovenga, D. Peduto, L. Cascini

Freeze-Thaw Cycle and Rockfall Monitoring

Among several weathering processes that may contribute to rock fall generation, a particular issue is related to freeze-thaw cycles. Several studies claim that many rock falls originate from thawing of the fractured bedrock during seasonal freezing (Matsuoka and Marton Permafrost Periglac Process 19(2):195–210, 2008; Matsuoka Cold Reg Scid Technol 17(3):253–270, 1990). Other authors have recently suggested that ice segregation is the real cause behind bedrock fracturing (Hallet Science 314(5802):1092–1093, 2006; Murton et al. Permafrost Periglac Process 12(3):255–266, 2001, Science 314(5802):1127–1129, 2006). Consequently, freeze and thaw processes will be deeply investigated in order to discover possible relationships between triggering mechanisms concerning rockfalls and monitoring datasets.

Laboratory tests have been carried out to investigate the rupture process caused by the abovementioned cycles. Preliminary analyses were performed both in lab and on the field with the aim of testing the capability of different transducers to register micro seismic signals.

Diego Arosio, Laura Longoni, Fabrizio Mazza, Monica Papini, Luigi Zanzi

Rapid Assessment of Landslide Activity in Emilia Romagna Using GB-InSAR Short Surveys

Rapid assessment of landslide activity is important in case of adverse climatic conditions leading to civil protection’s alerts that require increased surveillance of risk areas. GB-InSAR is nowadays becoming a consolidated near-sensing monitoring technique for slope movements. It can be installed rapidly and it can rapidly provide results in the form of displacement maps. However, it has never been thoroughly tested in radar-hostile conditions such as these posed by large-scale earth slides – earth flows covered by a canopy of trees bushes and meadows, that are the typical landslides in Emilia Romagna Apennine. As sparse small villages, buildings, roads and other lifelines are often built on these landslide bodies, they are of particular concern for civil protection, especially during prolonged rainfall periods that determine attention/alerting conditions. To test the possibility to achieve improved surveillance capability in case of attention needed, a series of GB-InSAR spot campaigns lasting from a week to a month, was carried out in 2010–11 in several landslides of Emilia Romagna Apennine using a commercial interferometric radar. The aim was to evaluate the performance of the technique for rapid assessment of landslide activity, even in case of partly vegetated soil coverage conditions. The paper deals with the results obtained in 3 out of the 11 monitored sites.

Alessandro Corsini, Matteo Berti, Antonio Monni, Marco Pizziolo, Francesco Bonacini, Federico Cervi, Giuseppe Ciccarese, Francesco Ronchetti, Eleonora Bertacchini, Alessandro Capra, Angela Gallucci, Mauro Generali, Giampiero Gozza, Valeria Pancioli, Sara Pignone, Giovanni Truffelli

Resolving Landslide-Bedrock Interaction by Nanoseismic Monitoring

Applying high-resolution Nanoseismic Monitoring to different slope instabilities in the Alps, we were able to observe the existence of fracture processes that resolve the creeping of slope material into sequences of discrete ‘slide quake’ events. At Heumoes slope, Austria, the locations of slide quakes are clustered in the mid-part of the slope exhibiting lower displacement rates than the remaining slope. In contrast, at the mudslide in Super-Sauze, France, the epicenters of located slide quakes correlates well with areas of highest displacement rates. These different behaviors are caused by the completely different layout of bedrock topography which directly influences dilatation and stress relief within the slope material.

Marco Walter, Manfred Joswig

SAR Interferometry for Landslides Risk Assessment at Local Scale: The Case Study of Castagnola (Northern Apennines, Italy)

In this work we describe the application of remote monitoring techniques based on radar interferometry (PSI and GB-InSAR) to assess the state of activity and the associated risks of the Castagnola landslide located in Northern Apennines (Liguria, Italy). The ongoing slope instability affecting the Castagnola area is a complex and still poorly understood phenomenon which in the last few decades has undergone numerous reactivations leading to damage to buildings and civil infrastructures. Following a geomorphological field characterization and an aerial photo interpretation of the site, we have analyzed and compared the past long term evolution of the ground movements using Persistent Scatterers Interferometry technique (PSI) from a set of ERS 1/ERS2 space-borne data acquired between 1992 and 2001 and the recent landslide displacements obtained from Ground-Based Interferometric Synthetic Aperture Radar (GB-InSAR) surveys. The results of the space-borne inteferometric data analysis have been compared both with the deformation measured at the head of 10 inclinometric tubes and with the openings of some cracks on buildings. The GB-InSAR monitoring has been carried out in three distinct campaigns from October 2008 to March 2009. The interpretation of the results has allowed to derive a multi-temporal deformation maps of the landslide, showing the up-to-date displacement field and the mean landslide velocity. On the basis of the outcomes of GB-InSAR monitoring, the pre-existent boundaries of the Castagnola landslide have been modified.

Francesco Antolini, Veronica Tofani, Chiara Del Ventisette, Guido Luzi, Nicola Casagli, Sandro Moretti

In Situ and Remote Long Term Real-Time Monitoring of a Large Alpine Rock Slide

We analyze a long term monitoring dataset collected for a deep-seated rockslide (Ruinon, Lombardy, Italy), which activity is documented by ground-based and remote sensing data since 1997. The monitoring data allowed to set-up and update the geological model, to identify rockslide complexities (e.g. uncertain geometry, composite failure mechanisms, seasonal behavior) and their impact on the reliability and early warning potential of monitoring data. GB-InSAR data allowed to identify different behaviors for sectors characterized by outcropping bedrock, thick debris cover, or close to major structures, and to set-up a “virtual monitoring network” by a posteriori selection of critical locations. Displacement time series extracted from GB-InSAR provide a large amount of data even in debris-covered areas, when ground-based instrumentation fails. Such spatially-distributed, improved information, validated by selected ground-based measurements, allowed to establish new velocity and displacement thresholds for early warning purposes.

Federico Agliardi, Giovanni B. Crosta, Rosanna Sosio, Carlo Rivolta, Gregorio Mannucci

C/X-Band SAR Interferometry Used to Monitor Slope Instability in Daunia, Italy

We apply multi-temporal Persistent Scatterer Interferometry (PSI) analysis to investigate slope instability in the Daunia region in the Southern Apennine Mountains. Daunia includes many small hill-top towns affected by landslides and is of particular interest for the Civil Protection – Regione Puglia Authority, one of the end users of the PSI deformation maps. The SPINUA algorithm is used to perform interferometric analysis and detect, with mm precision, the presence of ground surface movements. Consistent results on very slow displacements are obtained using the radar imagery acquired between 2002 and 2010 by the ENVISAT ESA satellite (C-band, medium spatial resolution sensor) and the images acquired between 2010 and 2011 by the X-band high resolution sensor onboard the TerraSAR-X satellite. Thanks to the finer spatial resolution the X-band PSI applications are very promising for monitoring single man-made structures and slope/ground instability in areas where C-band PS density is low.

Raffaele Nutricato, Janusz Wasowski, Fabio Bovenga, Alberto Refice, Guido Pasquariello, Davide Oscar Nitti, Maria Teresa Chiaradia

Landslide 3D Surface Deformation Model Obtained Via RTS Measurements

We present a new procedure that allows retrieving in near-real-time 3D surface deformation models starting from data acquired via Robotized Total Stations (RTS). The RTS measurements are first pre-processed and then implemented on 3D maps that include vector arrows representative of the intensities and of the real directions of motion in a given system of coordinates. The 3D surface deformation models are finally overlain on a DTM and/or on an updated picture of the monitored area. We discuss an example of application to an active large-scale landslide located in the area of Montaguto (southern Italy, ca. 100 km northeast from Naples). In this complex landslide scenario, the use of 3D representations of the surface deformation simplified the understanding of the evolution of the landslide phenomenon and received positive feedbacks from operators of the Italian Civil Protection Department.

Andrea Manconi, Paolo Allasia, Daniele Giordan, Marco Baldo, Giorgio Lollino, Angelo Corazza, Vincenzo Albanese

Application of SqueeSAR™ to the Characterization of Deep Seated Gravitational Slope Deformations: The Berceto Case Study (Parma, Italy)

SqueeSAR™ SAR interferometry is today one of the most advanced technologies for surface deformation monitoring capable of overcoming most of the limitations of conventional differential radar interferometry. It exploits long temporal series of satellite radar data, acquired over the same area of interest at different times, to identify “natural radar targets” where very precise displacement information can be retrieved.

Thanks to its capability to detect millimetre level displacements over long periods and large areas, SqueeSAR™ analysis can be considered complementary to conventional geological and geomorphological studies in landslide detection and monitoring, supporting the performance of landslide inventories at regional scale. The availability of surface displacement time series for all the radar benchmarks identified makes it also possible to change the scale of the analysis from regional to local, allowing an in depth study of the evolution of single instability phenomena, supporting the design of traditional monitoring networks, and even verifying the efficiency of remedial works.

The above approach was applied to study the Berceto deep seated gravitational slope deformation (DSGSD) (Parma, Italy) by processing satellite SAR data relevant to the 1992–2000 time span. By combining results obtained in both ascending and descending acquisition geometries, it was possible to retrieve both vertical and E-W components of surface displacements.

A correlation with the results of the geophysical investigations will be proposed, with a preliminary interpretation of the surface displacement trends in the upper part of the slope.

Andrea Tamburini, Sara Del Conte, Gianfranco Larini, Luigi Lopardo, Claudio Malaguti, Paolo Vescovi

Use of the Seismic Dilatometer (SDMT) in Landslide Research and Practice

This paper shows the use of the seismic dilatometer (SDMT) testing (Marchetti J Geotech Eng Division, 106:299–321, 1980; Marchetti et al. Proceedings of 2nd international flat dilatometer conference, Washington, DC, pp 7–48, 2001, In Situ tests by Seismic Dilatometer (SDMT), pp 109–138, 2008) in landslide diagnosis and monitoring. The quick K

D

-DMT method, developed by Totani et al. (1997) for detecting active or old slip surfaces, was recently applied in a research programme on stability conditions of natural slopes shaped in colluvial cover formations in Abruzzo region (Chieti, Teramo). The paper illustrates the capability of SDMT to identify remoulded zones, symptom of instability, and slip surfaces in the investigated slopes.

Moreover, the paper presents the possibility to use the DMT blade as a piezometer, to monitor rapidly the variation of the ground water level in relation to weather trend.

Sara Amoroso, Ferdinando Totani, Gianfranco Totani

Gravitational Instability Analysis of the Prato Carnico Village

This paper reports in situ test results and monitoring performed to characterise the development of a gravitational phenomenon. Analysis made it possible to create a 3D subsoil model to identify the main preferential paths of groundwater seepage, the boundaries of the subsidence area and the relationships between rainfall and displacements. The results of seepage and stability analyses highlight some aspects that characterise the kinematical mechanism of the slope. Displacements show a constant increase over time independently from the pluviometric regime. Stratigraphic sections and geophysical investigations highlight that the subsidence basin was formed just above a morphological bedrock depression and was filled with weathered gypseous arenite and sandy silt. The slow and constant sinking of the cover may be ascribed to the progressive collapse of the voids created through karstification within the gypseous rock mass and which attract loose material from above causing vertical and horizontal movements.

Marco Del Fabbro, Roberto Meriggi, Nicola Stefanelli

Rockfall Full Scale Field Tests

The phenomenon of rockfall along slopes is an environmental risk that frequently occurs in mountainous regions. In this phenomenon are directly involved infrastructures (railways, ordinary roads or highway) but also residential areas as well as individual structures are also interested in prevention and defense. Among different types of action taken into account to reduce the risk of rockfall, passive defenses are solutions widely adopted. In this field, the most frequently used are the elasto-plastic steel barriers, while greater resistance are offered by reinforced earth. University of Brescia has developed a special “test field” in Pezzaze (near Brescia) and in 2010 started a research activity with the aim of studying the phenomenon of rockfall both on elasto-plastic passive defenses and on reinforced earth.

Alberto Clerici, Ezio Giuriani, Danilo Cambiaghi, Antonio Isceri, Giorgio Vassena, Egidio Marchina, Luca Cominoli

Sprinkling Tests to Understand Hydrological Behaviour of Mudslide

The unsaturated zone buffers precipitation and controls groundwater recharges. Quantification of groundwater recharges is important for the improvement of hydrogeomorphological hazard analysis. The importance of fast preferential flow is recognized in literature, but its quantification remains difficult.

This paper presents the results from three 1 m

2

sprinkling experiments carried out in highly heterogeneous black marls of the Super-Sauze mudslide, in Southern French Alps. The aim of the experiments was to study the hydrological system within three morphological units characterized by different displacement rates and possible hydrological conditions. Special attention was given to identify and characterise the preferential flow patterns with the attempt for its quantification. The infiltration process was monitored with hydrological observations and hydrochemical tracers (Br

, Cl

). Based on the analysis of all available field data, conceptual models of the hydrological responses were proposed.

Dominika Krzeminska, Thom Bogaard, Taha-Hocine Debieche, Vincent Marc, Jean-Philippe Malet

High Resolution InSAR Monitoring of Coastal Landslides

Radar interferometry (InSar) techniques using images from several radar satellites are increasingly being used in slope stability assessment. During the past year there were at least 25 media reports of landslides, some fatal, occurring in various areas in Canada. In this paper, we provide examples of using high resolution (3 m) InSAR techniques from RADARSAT and TerraSAR X to monitor coastal landslide affectiong transportation corridors. The high-resolution InSAR images are very effective in characterizing differential motion within these low velocity coastal landslides. The active wet spring periods are better monitored by the more frequent revisits from TerraSAR X.

Vernon Singhroy, François Charbonneau, Junhua Li, Rejean Couture

Evaluation of Temperature Effects on Strain Measurements with DTSS

Field measurements are exposed to daily and seasonal temperature variations due to meteorological and hydrological events. This paper presents the obvious influence of temperature on strain measurements with DTSS. Tests with wide range temperature variations inside the reference section and the strained section were performed. Moreover, temperature effects on different system configuration relating reference section types are investigated. Results show temperature compensated as well as uncompensated strain of DTSS measurements. Finally, a manual temperature compensation was accomplished for comparison to DTSS temperature compensated strain.

Gerhard Kapeller, Rafael P. O. Rocha, Luiz Alkimin de Lacerda, Markus Aufleger

Measurements of Hydraulic Subsurface Processes by Means of Distributed Fiber Optic Temperature Sensing (DTS)

Distributed Fibre Optic Temperature sensing (DTS) system allows the monitoring of geo-hydrological changes of boundary conditions due to rainfall. Based on the heat transport in soils the temperature distribution is closely correlated with the presence and movement of water in soils. Therefore rainfall infiltration as well as the degree of saturation as common landslide triggers can be monitored in a distributed way. The advantage of continuous measurements over several kilometers of cable and its robustness allows a long-time and early warning monitoring for landslide occurrence. This paper represents the potential and installation of DTS for monitoring of infiltration processes and degree of saturation in soil. Therefore about 600 m cable were installed at two scientific interesting test sites in Austria. In total an area of about 1,200 m

2

was instrumented. The results are based on natural and artificial rainfalls.

Gerhard Kapeller, Thomas Etzer, Markus Aufleger

Applying GPR and 2D ERT for Shallow Landslides Characterization: A Case Study

We present a procedure to estimate the characteristics of small shallow landslides based on the application of ground penetrating radar (GPR) and 2D electrical resistivity tomography (ERT). Existing procedures based on either conventional or non-invasive geophysical methods, observe almost exclusively large and deep landslides. Verification has been done on a small shallow landslide in the village of Vinča, near Belgrade, Serbia. The proposed procedure is realized in two simultaneous steps. First, from high resolution raw data obtained by GPR survey, soil horizons inside and near landslide body are estimated up to 4 m deep. The rupture surface is defined and its depth is estimated at 1.7 m. Second, ERT technology confirmed and integrated the results obtained by GPR survey. Main advantages of proposed procedure are efficiency and applicability for small shallow landslides whose number and impact on environment is dominant.

Biljana Abolmasov, Aleksandar Ristić, Miro Govedarica

Monitoring and Modelling of Rainfall-Induced Landslide in Volcanic Soil Slope

Reactivated landslides have often posed a significant hazard to human lives and properties in many regions of Indonesia. In order to mitigate the hazard, a better understanding of mechanism leading to the reactivation of landslides is necessary. For this purpose, a long-term monitoring and numerical analysis of an active landslide in a volcanic soil slope in West Java, Indonesia was conducted. Monitoring instruments consisted of jet-fill tensiometers, inclinometers, open stand-pipes, and a tipping-bucket rain-gage. The records of pore-water pressure responses of the soil slope show that a transient perched water table could develop within the shallow soil profile, and the groundwater table could rise significantly in the middle portion of the slope during heavy rainstorms. Meanwhile, the inclinometer records show the existence of a multiple sliding zone at a maximum depth of about 17 m. Based on the monitoring data, a couple analysis of seepage and slope stability was performed to evaluate the effect of rainwater infiltration on long-term stability of the slope. The numerical results indicated that the total rainfall of at least 550 mm, with intensity of more than 80 mm/day was the triggering hydrological condition for reactivation of the landslide.

Adrin Tohari, Khori Sugianti, Katsumi Hattori

Impact Pressure Measurements in Shallow Landslides

We reproduce shallow landslides by releasing 50 m

3

of debris mixture down a 40 m long and 30° steep slope. The slope is instrumented in order to measure front and surface velocities, flow height and impact pressure on small obstacles. The mixture properties are determined from analysis of material samples. The impact process is investigated on the basis of the undisturbed flow properties 4 m upstream of the obstacles. Impact coefficients relating mixture density and surface velocity to the impact pressure are computed from the front to the tail of the flow.

Bugnion Louis, Wendeler Corinna

Application of Terrestrial Laser Scanner to the Assessment of the Evolution of Diachronic Landslides

During the diachronic evolution of landslides, slope-morphology changes may be detected and assessed by using high-resolution digital models. Slope deformation is detected by scanning sequences over a given time period. This paper presents the results found combining TLS digital models and Global Navigation Satellite Systems in the detection and assessment of reactivations and differential displacements of two slides located at the SW of Sierra Nevada (Spain) between 2008 and 2010. In the first landslide a maximum downward movement of 1.2 m at the top was measured, whereas below the middle part of the mass, 1.3 m of maximum advance was established with a maximum displacement gradient of 1.04 m/year. In the second landslide, downward displacements with gradients between 0.32 m and 0.56 m/year were found, corresponding to rupture movements in incipient to initial stages of evolution. The combined use of TLS and GNSS enabled a quantification and mapping of complementary terrain features which are considered useful in forecasting further activity and slope evolution of these landslides. The high resolution and accuracy of the techniques applied offer broad possibilities in the spatial location of the slope movement and also in forecasting its diachronic activity.

José A. Palenzuela, Clemente Irigaray, Jorge D. Jiménez-Perálvarez, José Chacón

Ground-Based Radar for Permanent Monitoring of Landslides

Large uncontrolled avalanches pose a hazard to both people and infrastructure. Timely warning of potential avalanches can save lives and reduce damage to the infrastructure. However, access to the potential landslide area can be difficult and electronic monitoring equipment installed at the site may fail. This paper presents a radar system for remote monitoring using interferometric measurements. The radar can be installed several kilometres away from the potential landslide area and movements in the landslide can be monitored with an accuracy better than 1 mm. The data can be presented remotely in real time and a warning can be issued automatically to the relevant authorities if movements are registered. ISPAS installed the first permanent radar for monitoring a rockslide area in 2006 and the second radar in 2009. The paper presents the technical solution and experiences of the remote monitoring of the landslide areas in Tafjorden and Åknes, Norway.

Richard Norland, Rune Gundersen

The Ganderberg Landslide (South Tyrol, Italy): Mitigation of Residual Risk by Real-Time Monitoring

The whole flank of Ganderberg western slope (3.75 km

2

) (lat. 46°51′12″, long. 11°10′15″) is involved in a Deep Seated Gravitational Slope Deformation phenomenon. The upper part is characterized by several joint surfaces, with possible wedge failure mechanisms. In particular, the northern crown ridge is divided into three sectors with noticeably different indications of subsidence and displacement. The orientation of the joint planes and evidence of vertical movements of a distinct rock block allow a potential rock avalanche to be hypothesized (up to the volume of 4.5 × ;10

5

m

3

). On the basis of historical archives analysis it was found that the same slope was involved in a rock avalanche event dating back to 1401. The landslide deposits created a 35 m deep lake, damming the Passer Torrent, creating the Passeirer Wildsee or Kummersee.

Aim of the study is the evaluation of residual risk scenarios and its mitigation by means of monitoring and data interpretation using Saito and Fukuzono techniques.

Martina Stefani, Matteo Mantovani, Volkmar Mair, Gianluca Marcato, Alessandro Pasuto, Ludwig Nössing

The Case History of the Bagnaschino Landslide, from Early Warning to Site Specific Rainfall Threshold

The highway n° 164, in 1994, was struck by a complex composite landslide activated in Bagnaschino (Torre Mondovì, Cuneo) due to flood events. In order to continuously monitor the stability conditions, the Cuneo County established a borehole monitoring plan in 2008 with DMS column 60 m long. DMS (patents CSG Srl Italy) is a multiparametric system for the stability monitoring of slopes, excavation fronts and engineering works; the column is like a spiral cord composed of a sequence of hard tubular modules connected to each other by special flexible junctions. Correlation between DMS column and rain data allowed identifying critical events that have reactivated the landslides, along the sliding surface at 7 m blg, allowing the adoption of preventive interventions (closing the road during the March 2011 rain event). Moreover with the DMS system was possible to calculate the site specific rainfall threshold curve that shows the limit stability condition related to the rain intensity and duration.

Corrado Faletto, Enzo Novello, Paolo Tible

Application of Monitoring Data for the Prediction of the Time to Failure and Risk Management

During the past decades, excavation in open mine has been planned based on “more extraction with low cost”. This resulted to the poor management of excavation and consequently, slope instability in many open pit mines. Anguran zinc and lead open mine in Zanjan Province, northwestern of Iran is an old mine that has been excavated since 1940 and is one of the examples of improper management that has encountered to several instabilities in its northern and western flanks. The economic importance of the operation of this mine and high risk of landslide occurrence put this mine as of the main concerns of the local governor.

The investigation has been done through detail field study together with high precision monitoring of unstable blocks. It was found that the main landslide in this mine is a creep type of motion that caused by overlying a block of hard limestone on a low strength clay bearing schist. It was also concluded that in a creep type of landslide, independence of the rate of motion from its initial triggering factor such as rain is a good indicator for predicting the time of rapid failure and for controlling the risk by proper evacuation plans.

Ziaoddin Shoaei, Karim Karamsoltani

Development of WILMS: Well Inform Landslide Monitoring System for USM Healthy Campus

Slope monitoring system was installed for the purpose of monitoring the hill development for student accommodation which houses three main blocks of hostels. This was implemented under a special programme known as Healthy Campus which covers all aspects conducive to student, staff and environment. A full package of pilot study has been conducted by a group of experts in the field to run a monitoring and mitigation system for Universiti Sains Malaysia (USM) hostels. WILMS (Well-Inform Landslides Monitoring System) is a real-time web monitoring system which integrates the use of SMS (Short Messaging Services) and MMS (Multimedia Messaging Services) technology to inform and to alert users of different needs about the presence of a pessimistic change in land stability. The uniqueness of this application is that it makes monitoring job easier, without needing constant human power while maintaining accurate data acquisition cocpyntinuously and reducing human errors. This method is offering cheaper solution as well as sustaining environmental issues.

Fauziah Ahmad, Ahmad Shukri Yahaya, Mohd Azam Osman, Wong Poh Lee, Ahmad Badri Ismail

Integrating Landslide Monitoring into Multi-Hazard Monitoring Systems

Civil Protection of Regione Calabria, in cooperation with the regional Multi-Risk Functional Centre, chose CAE to carry out the implementation of a landslide real-time monitoring solution. The landslide happened during February 2011 at Cirò, located within the Crotone Province. In June 2011 CAE completed the installation of the real-time landslide remote monitoring system. Data measured by a number of geotechnical sensors placed in relevant points are received at the regional Multi-Risk Functional Centre, located in Catanzaro Province. Among the strengths of this innovative solution developed by CAE, the leading Italian provider of multi-hazard monitoring systems, there is the opportunity to use traditional geotechnical sensors in a new and innovative manner. Their wireless and remote usage in real-time proved to make easier the implementation without affecting reliability of data measurement and collection. Three months after the activation of the system, data are nearly 100 % collected and transmitted in real time, with no interruption in data availability.

Guido Bernardi, Fabio Procopio

Early Warnings and Emergency Plans

Frontmatter

An Appraisal on Ongoing Practices for Landslide Early Warning Systems in Selected South and East Asian Countries

It is widely acknowledged that Asia is the world’s most disaster prone region, with nearly two-thirds of global disaster mortality and morbidity occurring within the region. The IPCC Working Group II noted that heavy precipitation events are very likely to increase in frequency and will augment the multi-hazard risk scenario in most of the countries. Extreme weather events, such as cloud bursts and heavy concentrated rainfall, especially in some parts of Asia, have been blamed for loss of life and property in the region. Landslides have been triggered during these events causing further casualties.

In consideration of the aforementioned events, the Asian Disaster Preparedness Center (ADPC) in collaboration with the Norwegian Geotechnical Institute (NGI) in Oslo, Norway is implementing a “Regional Project” on sharing best practices for early warning of landslides with participation from 11 countries. The project, which is financed by the government of Norway, includes the countries Bangladesh, Bhutan, China, India, Indonesia, Nepal, Pakistan, the Philippine, Sri Lanka, Thailand, and Vietnam.

This ongoing project aims to document, share, enhance and develop sound practices for early warning of landslides for sustainable development in affected areas. This is currently being achieved through gathering of data from existing approaches and through formation of joint working groups to identify critical factors and disseminate knowledge from participating countries.

This paper describes the current status of landslide early warning systems in the participating countries with emphasis on the identification of critical elements for an effective early warning approach.

Elmer B. Billedo, Rajinder K. Bhasin, Oddvar Kjekstad, N. M. S. I. Arambepola

Examples of Cost Effective Practices for Landslide Monitoring for Early Warning in Developing Countries of Asia

In recent times landslides and mass movements have become widespread events, posing great problems and serious challenges to development process especially in mountainous areas of developing nations in Asia. They have increased both in frequency and intensity and have assumed catastrophic and disastrous proportions in number of countries such as China, Indonesia, Pakistan, Sri Lanka, causing extensive damage to life and property. Mass movements occur as a result of heavy precipitation or as a secondary hazard triggered by geological events such as earthquakes, volcanic eruptions etc. In addition to its triggering factors, increase in landslide occurrence has been associated with a combination of factors and several attributes such as geological, topographic, morpho-metric, climatic and anthropogenesis nature that directly or indirectly contribute to the phenomena of slope instability.

A review of available literature emphasizes the role of landslide monitoring as an important controlling factor if the observation of initiation of slope failures can be introduced as a preparedness measure. Landslides are often triggered in areas with past landslide history and monitoring of landslides using community based approaches is considered as an effective measure for limiting the damages from landslides. In most areas development activities seems to be responsible for reactivation of dormant landslides. Hence communities living in areas with landslide history should be warned in time through constant monitoring and early warning of potential reactivation. In addition, slow moving slides on hill slopes need constant monitoring as many of developing countries in Asia cannot afford to undertake mitigation measures or to resettle people to safer areas after identification of the potential threat.

Realizing the importance of recording sound and cost effective practices of landslide monitoring for early warning, the Asian Disaster Preparedness Center (ADPC) in collaboration with the Norwegian Geotechnical Institute (NGI), Norway is implementing a “Regional Programme (RECLAIM)” for documenting and sharing good practices for early warning of landslides with the participation of mandated national institutions for landslide related activities from Bangladesh, Bhutan, China, India, Indonesia, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, and Vietnam. The Programme receives financial assistance from the government of Norway. This paper presents some of the examples of landslide monitoring initiatives from Sri Lanka implemented by the project partner National Building Research Organization (NBRO).

R. M. S. Bandara, Rajinder K. Bhasin, Oddvar Kjekstad, N. M. S. I. Arambepola

Validation and Interpretation of Monitored Behavior of Slopes Vulnerable to Failure

Monitoring and early warning is one of the most promising ways toward reduction of disasters induced by landslides and slope instabilities. Although less costly than construction of retaining walls and other mechanical measures, early warning has several problems to be overcome. First, it is often the case that the exact location of an unstable soil mass is not defined and hence the location of monitoring sensors cannot be decided. This problem can be solved by installing many low-cost sensors within a possibly unstable slope. The second problem concerns what information of slope should be monitored. The present study has developed a low-cost MEM sensor unit that can monitor slope deformation during heavy rainfall. A wireless network collects signals from the sensors periodically and helps the local government issuing an alert signal or emergency evacuation order, depending upon the progress of tilting. It is further important that the low cost of the sensors allow individuals to purchase personally and installs them in order to protect themselves from slope disasters. The developed equipments have been deployed in several slopes in the recent times for validation of their field performances. The present text reviews the obtained records and discusses their use for practice.

Taro Uchimura, Ikuo Towhata, Lin Wang, Jianping Qiao

Overview of Some Empirical Methods to Correlate Rainfall and Shallow Landslide and Applications in Malaysia

Malaysia is located in a tropical region, known to have an extremely high annual rainfall which frequently triggered a landslide. If a landslide early warning system to be developed in Malaysia, it should be implemented based on empirical correlation of rainfall data and landslide cases. The proposed method is more economical compared to physically based approach. In this paper, two types of empirical rainfall thresholds were discussed i.e. (1) Intensity versus Duration (ID) and (2) Intensity versus Working Rainfall. Three efforts in correlating rainfall and landslides empirically in Malaysia were also been discussed. Intensity versus Duration (ID) method was used for works in Ampang/Hulu Kelang and Penang areas whereas Intensity versus Working Rainfall method was used for Cameron Highland area.

Suhaimi Jamaludin, Faisal Hj Ali

Experimental Alert Model for Hydrogeological Risk: A Case Study in Sicily

The north-eastern part of Sicily (Messina district) is often hit by violent storms that cause great damage resulting from flash floods and debris flows. On 1st October 2009 there were 37 victims and on other occasions events have led to serious risks to both public and private safety.

The environment is characterized by the presence of high slopes, clay terrains deriving from mainly metamorphic rocks, and intensely inhabited territories: conditions that make risk mitigation measures particularly difficult.

Since there is very little time between the event of rainfall and the subsequent need for preventive intervention, the preparation of a civil protection system is a fundamental requirement.

For these reasons the Sicilian Department of Civil Protection has an ongoing series of initiatives that seek to reduce response times: instrument installation (rain and temperature sensors, X-band meteorological radar), development of an alert model based on critical rainfall thresholds, and the development of a plan for activating civil protection procedures.

Giuseppe Basile, Marinella Panebianco

An Operational Warning System for the Forecasting of Landslide Occurrence at Regional Scale

In this work we present a regional scale warning system (named SIGMA) for rainfall induced landslides. The system combines rain gauges measurements and rainfall forecasts and compares them with a series of statistical rainfall thresholds based on the total amount of rainfall. The system was specifically built to take into account both shallow and deep seated landslides. A decisional algorithm integrated in the warning system automatically provides a criticality level depending on which thresholds are exceeded. The model was integrated in the regional warning system of the Emilia Romagna region (Italy) for civil protection purposes. This paper accounts also for the main modifications that the model had during its development, passing form a base version relying on thresholds defined by means of a statistical analysis on rainfall data, to an advanced version in which thresholds were calibrated using a landslide database. The passage from a system to another was straightforward and for its flexibility and versatility, the proposed methodology seems particularly appropriate for emerging countries that have not yet gathered extensive and complete information on the location and time of occurrence of landslides.

Samuele Segoni, Gianluca Martelloni, Daniela Lagomarsino, Riccardo Fanti, Filippo Catani

Radar Interferometry for Early Stage Warning on Monuments at Risk

Prevention measures on monuments affected by landslides and instability processes can effectively avoid damages to the elements at risk if the warning phase takes place at an ‘early stage’, i.e. when the phenomena are not completely triggered and developed. To realize this warning approach, satellite and ground-based radar interferometry techniques were tested, exploring their capabilities for detection and monitoring of structural deformation on the monuments of archaeological areas in Rome (Italy). Thanks to a procedure shared with the local conservators, fully involved in both investigation and feedback phases, early stage warning was carried out. Updated mapping products were obtained, identifying the most critical sectors to be stabilized. The recognition of definite deformation patterns allowed a high level of alert to be activated because of the significant threat for the monument conservation and public safety. Temporal series analysis highlighted the onset of probable instability processes, suggesting appropriate mitigation countermeasures.

Deodato Tapete, Nicola Casagli, Riccardo Fanti

Landwarn: An Operative Early Warning System for Landslides Forecasting Based on Rainfall Thresholds and Soil Moisture

The Umbria Region is one of the Italian areas that are most prone to landslides and floods. For early-warning procedures aimed at the reduction of the hydrogeological risk, the rainfall thresholds represent the main component of the Italian Civil Protection System. To improve the performances of the alert system for landslide risk, the Umbria Region CFD, in cooperation with the Research Institute for Geo-Hydrological Protection (IRPI-CNR), developed and tested a continuous physically-based soil water balance model, addressed to the estimation of soil moisture conditions over the whole regional territory prior to severe landslide events. The relationship established between the maximum cumulative rainfall values and the soil moisture preceding the triggering of landslides allows to dynamically adjust the rainfall thresholds as a function of the estimated soil moisture values. The main components of the new early-warning system (named LANDWARN) for landslide risk prevention operating at the CFD are: (1) the observed and 72 h-predicted cumulative rainfall from the dense regional hydrometeorological network; (2) a local area meteorological model, known as COSMO ME; (3) the soil water balance model by Brocca et al. 2008; and (4) a web-based Information System. All these elements are arranged in a MATLAB-based flux of operations. Nowadays, the system is still under development and implemented at three different scales: (1) for a specific rockslide site, where a real-time extensometer network is available; (2) for 110 high-risk landslide sites located across the whole regional territory; and (3) for the whole regional territory over a regular grid. Further steps of the implementation are currently in progress. In particular, a GIS-based physically-based model that combines the hydrological information with a simple slope stability analysis is being validated in a test-area of the Umbria Region (Salciarini et al. Nat Hazards 9739–9742, 2011), with the aim of evaluating the possibility of developing an early-warning system capable to take into account the mechanical and physical characteristics of the slopes, besides rainfall and soil moisture.

Francesco Ponziani, Nicola Berni, Marco Stelluti, Renato Zauri, Claudia Pandolfo, Luca Brocca, Tommaso Moramarco, Diana Salciarini, Claudio Tamagnini

Method of Residual-State Creep Test to Understand the Creeping Behaviour of Landslide Soils

Many researchers have studied creeping behaviour of landslide soils in the laboratory using both odometer and triaxial tests; however in most cases, they have only concentrated on the pre-peak creep behaviour of soil, which does not adequately explain the creep movement of landslides that undergo large displacements at close-to-residual state of shear. This necessitates the importance of further studying creep behaviour of clayey soils in residual-state of shear. In order to investigate creep behaviour of clayey soils, a method of residual-state creep test in a modified torsional ring shear machine is developed in laboratory, which can simulate the creeping behaviour of a large-scale landslide. This paper discusses on the typical results obtained from four representative landslide soils, i.e., commercially available Kaolin clay and three other samples from the landslide area in Japan and Nepal which have higher percentage of smectite, chlorite, and mica. Finally, possibilities towards displacement prediction are discussed.

Deepak Raj Bhat, Netra P. Bhandary, Ryuichi Yatabe

Operational Procedure for a Hydrogeological Warning System in Aosta Valley

The main mission of a Functional Centre consists in the daily issuing of the “criticality bulletin” defining the alert level for hydrogeological and hydraulic risk at regional scale. The forecast system of the hydrogeological risk in the Aosta Valley used to be based on a threshold system, developed by the Italian Civil Protection Department. The operator was used to decide the alert level on the basis of his experience, using the maximum precipitation threshold as the only indicator for landslide triggering processes. A new operational multi-parametric threshold system has been developed, taking into account the maximum precipitation and the snow level too, calibrated through a back analysis of the previous 10 years. At the same time a new procedure has been drafted in order to take advantage of the experience acquired by operators and to uniformize the warning selection criteria. A new method to predict criticality scenarios has been developed and it is now being tested.

Sara Maria Ratto, Hervé Stevenin, Evelyne Navillod, Marco Cauduro

Defining Physically-Based Rainfall Thresholds for Early Warning Systems

Empirical rainfall thresholds compiled on correlations between recorded data show that precipitation intensities and durations required to trigger shallow landslides vary with climatic, geotechnical and topographic conditions; consequently, thresholds exhibit a high degree of spatial variability, even across relatively small geographic areas (see, e.g., Baum and Godt (Landslides 7:259–272, 2010; Guzzetti et al. Landslides 5:3–17, 2008). In order to define intensity/duration rainfall thresholds capable of considering the site-specific hillslope characteristics, GIS-based modelling techniques have been developed and successfully applied starting from Iverson’s theory (Baum et al. TRIGRS – a Fortran program for transient rainfall infiltration and grid–based regional slope–stability analysis, version 2.0, 2008; Godt et al. Rev Eng Geol 20:137–152, 2008; Salciarini et al. Eng Geol 102:227–237, 2008). In this work A GIS-based code is presented which permits the assessment of the spatial distribution of the minimum rainfall intensity that triggers shallow landslides and debris flows over a given study area, based on the rainfall duration and the local geometric, hydrologic and mechanical characteristics of the slopes. Such an approach is used for predicting landslide scenarios produced by short-duration rainfalls. An example of application to a study area of the Umbria Region in central Italy is presented, describing the capability of the model of providing site-specific thresholds for different rainfall scenarios and issuing different levels of hazard warning. The application illustrates some challenges on the technically feasibility of shallow-landslide early warning systems, capable of including specific information on the affected areas, probability of landslide occurrence and expected timing.

Diana Salciarini, Claudio Tamagnini, Francesco Ponziani, Nicola Berni

Rainfall Threshold Analysis and Landslide Susceptibility Mapping in Wudu County

The main purpose of this study is the analysis of rainfall thresholds and landslide susceptibility mapping in order to assist the prediction, mitigation and management of slope instability in the Wudu county in China. Firstly, the rainfall thresholds were assessed using the Antecedent soil water status (ASWS) model based on landslides induced by multi-temporal rainfall events in the Wudu county. Secondly, three separate susceptibility maps were produced using historic landslide inventories, and inventories reflecting single landslide triggering events, i.e. the 2008 Wenchuan earthquake and heavy rain storms. The separate maps were combined to illustrate the maximum landslide probability of all three landslide susceptibility maps. The results show that rainfall thresholds could be applied to forecast rainfall-induced landslides, and the integrated landslide susceptibility map could be used for planning of spatial development as well as emergency response actions.

Shibiao Bai, Jian Wang, Thomas Glade, Rainer Bell, Benni Thiebes

Cloud Monitoring: An Innovative Approach for the Prevention of Landslide Risks

Early warning systems (EWS) applied to geohazards and landslides should rely increasingly on cutting edge multi-parameter monitoring systems. These aim to provide both the best insight in the physics and then reach the best time delay required by decision makers. In addition, monitoring geohazard on the long term is becoming an increasingly multi-stakeholder process, involving various interacting actors with different roles. Seamless access to dataset, easy-to-read advanced results and technical information of interest to be shared between numerous actors is becoming all the more important. Then, in the same manner as in the computing field, cloud monitoring technologies and solutions may pace rapidly the next generation of monitoring services. The paper intends to give a brief overview of this prospect, focusing on recent information technology breakthroughs and considerations on the cost benefit of such a network centric approach. The e.cenaris cloud monitoring data center developed by INERIS, France, is evocated along with further linked prospects related to the research undertaken by the authors.

Bigarré Pascal, Verdel Thierry, Klein Emmanuelle, Gueniffey Yves

Landslide Triggering and Local Rainfall Thresholds in Bradanic Foredeep, Basilicata Region (Southern Italy)

It is recognised that a lot of the landslides occurred in the Mediterranean region are triggered by short intense storms. Due to its geological, geomorphological and climatic settings, the Bradanic Foredeep (Basilicata region) is affected by the widespread presence of landslides. The main objective of this paper is to identify the empirical triggering thresholds in Bradanic Foredeep and to investigate the role of antecedent rainfall. Using a variety of information sources, we have compiled a catalogue listing 97 rainfall events linked to landslides triggering in the investigated area. For each event in the catalogue, the exact or approximate location of the landslide and the time or period of initiation of the slope failure is known, together with information on the rainfall duration D, and the rainfall mean intensity I , that have resulted in the slope failure. The local rainfall threshold for the study area has been established using the statistical Frequentist approach. The comparison with regional thresholds proposed for other Italian regions has revealed that the Bradanic Foredeep thresholds are lower; which is probably due to the different quality of rainfall dataset. In fact, all the previous threshold have been evaluated starting from hourly data, while for the Basilicata region only daily data are available. Throughout this study we could not identify a significant correlation between antecedent rainfall and critical rainfall.

Maurizio Lazzari, Marco Piccarreta, Domenico Capolongo

Development of Debris Flow Early Warning System for Volcanic Rivers at Mt. Merapi Area

The 2010 Mt. Merapi eruption has produced approximately 140 million m

3

of pyroclastic deposit, in which more than ten million m

3

deposits are potential to move downstream through Boyong/Code River towards Yogyakarta City. The flow behavior of Code River may be affected by the presence of accumulated sediment at the upstream of the river (namely Boyong River). By rainfall trigger, this potential source can cause debris flow disaster that may contribute damage to the settlement areas in Yogyakarta City. This paper presents the development of early warning system to mitigate the impact of debris flow disaster along Boyong/Code River as revealed by most adaptive, least cost, and collaborative-based technology. The system was developed by considering the community aspiration in determining the types and placement of monitoring equipment, and maintaining its sustainability.

Teuku Faisal Fathani, Djoko Legono, Adam Pamudji Rahardjo, Dwikorita Karnawati, Irawan Eko Prabowo
Additional information