Recent Trends in Application of Electrical Resistivity Tomography for Landslide Study (original) (raw)
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The depth of the slip surface and thickness of the overburden deposit play a major role in assessing the slope stability of a landslide. Electrical Resistivity Tomography (ERT) survey was carried out in the Taprang Landslide, Kaski district, west-central Nepal to determine subsurface lithological conditions, depth and geometry of the slip surface. Wenner and dipole-dipole arrays were mainly applied in this ERT survey. The electrical resistivity survey revealed that there is a wide range of resistivity value which shows different kinds of layers in the subsurface, and the boundaries between these layers played a significant role to identify the slip surface. The data show mainly three layers from surface to bottom. An upper layer represents the dry to saturated colluvium and sandy gravelly soil (500 to 8000 Wm), the middle layer is highly-saturated soil with low resistivity value (100-700 Wm) and unweathered fresh bedrock of schist and quartzite with high resistivity value (1000 to 8000 Wm) at the bottom layer. The slip surface is considered as depth 25 m at the crown, 10-20 m at the main body part, and below 50 m at the toe and curved in geometry which indicates the rotational type of landslide. Investigation of the slip surface in a landslide using the ERT survey aids to know the slope stability.
Determination of the Landslide Slip Surface Using Electrical Resistivity Tomography (ERT) Technique
Advancing Culture of Living with Landslides, 2017
Indonesia is located among three interacting active tectonic plates, causing the country to become vulnerable to geological disasters; landslides being one of them. Deforestation and overpopulation on the hillsides have escalated the formation of critical areas where landslides and other geological disasters are an occurrence. It is therefore important to study the geometry and the depth of the slip surface of a critical area in order to recognize the indicator of landslides. In situ geophysical techniques enable the measurement of physical parameters, either directly or indirectly (via satellite), linked with the lithological, hydrological and geotechnical characteristics of the terrains related to landslides. The objective of this research is to determine slope stability analysis using a geophysical method described as Electrical Resistivity Tomography (ERT). Data from 1-D and 2-D Electrical Resistivity Tomography (ERT) analysis conducted in Cianjur, West Java-one of the most critical areas for landslides due to its steep hilly areas-showed that there was a contrast in the resistivity value. It showed different kind of layers in the soil, and the boundaries between these layers played a role as a slip surface. The data also showed that there were two slip surfaces in the research area: at the bottom and the top of the slopes. These provided the margins between the higher resistivity value of the upper layer and the lower resistivity value of the lower layer. The upper layer was concluded as clay soil and the lower one as more sandy soil. Determining slip surface using ERT helps to analyze the stability of the slope.
2014
The electrical resistivity tomography (ERT) survey has been deployed to accurately shed more light of a small landslide located near the Buzad village, Timis County, Romania. This slide actually represents a local reactivation during 2006 of an old landslide. A 2-D resistivity survey along three profiles over the landslide main body using a Wenner configuration was performed in 2007, 2012 and 2014. The results obtained provide useful information about the geometry and characteristics of the landslide, the depth and extension of landslide body. The ERT measurements indicated some zones associated with both the high water content and the clay content within the landslide body, divided by a compact sandstone mass that influenced the slide development.
Determination of shear surface of landslides using electrical resistivity tomography
Contributions to Geophysics and Geodesy, 2014
Geophysical methods offer a broad spectrum of information by dealing with slope deformations. The electrical resistivity tomography (ERT) method is mainly applied for spatial localization of the landslide body and depicting the shear zone position. This article presents the application of the ERT method for the landslide hazardous areas by means of numerical modelling. Four different synthetic models with very small resistivity contrast (30 Ohm.m/50 Ohm.m), where each model represents a different type of slope deformation, were tested by several factors affecting the final inverse model: measurement point density, L1 and L2 norm and L-norm roughness filter components. The higher measurement points density helps mainly to detect the boundaries at greater depths. Inverse models computed using the L1 norm bring satisfactory results for compact anomalous bodies, i.e. water saturated landslide body. In the case of subtle conductive zones, i.e. shear planes, the L2 norm based inversion is...
Environmental Earth Sciences (2019) 78:430, 2019
Pakhi landslide is one of the major debris slides of retrogressive nature along national highway (NH-58) corridor from Rishikesh to Badrinath in Garhwal Himalayas, India. The present work is the first such attempt in one of the landslides in Indian Himalayas and in the present case study, the subsurface characterization of the landslide was carried out with an aim to correlate the subsurface lithology, slip surface and geometry of the landslide using borehole investigation and electrical resistivity tomography (ERT) techniques. The results from ERT survey along and across the landslide could help to delineate different strata layers; thereby deciphering the probable slip surface of the landslide activity. Further, based on the landslide model drawn from the ERT interpretations, it can be stated that the crown portion of the right flank is more vulnerable to sliding phenomenon and that of the left flank is more prone to erosion. The results obtained from both the borehole investigation and ERT techniques are observed to be in great agreement and could complement each other for subsurface detailed investigation of landslide. The integration of both these techniques provides useful information about the landslide activities and defines the geometry of the landslide. Hence, it will be quite helpful in planning mitigation strategies as well as usefulness of each of these techniques.
Prediction of the Process of a Slowly Moving Loess Landslide by Electrical Resistivity Tomography
A slowly moving loess landslide along the River Danube in South Hungary was studied using electrical resistivity tomography (ERT). The aim of the research was to determine the fracture system of the study site. It seems to be the only possibility to get information about the landslide and its further evolution due to the homogeneous composition of the loess. The mass movement was expected to occur in the direction of the identified crack openings. The applicability of the ERT technique for such a supposedly dense fracture system was studied by numerical modelling and the results have been verified in the field. It was shown that it is especially important to carry out the field measurements following dry periods; otherwise the interpretation may become extremely difficult if not impossible. The dip of the fractures could not be observed and they could not be explored deeply. It was possible to map their surface projection to get the desired information about the structure of the landslide. Fracture zones could be especially well localized enabling the prediction of the positions of future rupture surfaces and thus also the delineation of the endangered zone. Although the area outside of the one that already subsided is not endangered yet, the area which has already started to move is going to break into two. Parts of the about 5 m wide blocks at the front of the landslide may fall or slide down anytime. The area below the buildings was assumed to move as one unit. Most of our predictions have been verified by the mass movements which occurred about one and half years after the measurements. The ERT method proved to be a good tool to characterize the fracture system of such a landslide area, enabling the prediction of future rupture surfaces and also delineation of the endangered area. Its use is therefore highly recommended to monitor landslides.
Fracture network characterisation of a landslide by electrical resistivity tomography
Natural Hazards and Earth System Sciences Discussions, 2014
In contrary to most of the landslide studies which concentrate to the sliding surface in this paper the fracture system of a loess landslide is investigated. The continuity and geometry, orientation and dip of the major fractures are crucial parameters for assessing rock stability and landslide evolution. Rain infiltrating moreover easily into the rock mass through fractures providing lubrication for the material to slide, and increases the self-mass of the material increasing the slumping rate. Fracture maps enable beside of the characterisation of the fractured area the delineation of the endangered area of slow-moving landslides in due time and getting information about its inner structure. For constructing such maps Electrical Resistivity Tomography (ERT) measurements have been carried out using different geoelectric configurations. In spite of the high density of the fractures and their changing physical parameters in function of their water content – which make the interpretat...
Journal of Science and Application Technology, 2019
Institut Teknologi Sumatera (ITERA), ITB and local governments had been cooperated in establishing an astronomy observatory of ITERA Lampung (OAIL), which was located at Mt. Betung in the Pasawaran area. Geological setting of this area showed that the dominant lithology of Mt. Betung is pyroclastic, andesite, and breccia rocks. These volcanic deposits have the potential to move the materials down-slope by the force of gravity, steep slope, and high water-content. We have investigated some area with the potential of a landslide along OAIL construction area, which may be the cause of the landslip as well. We applied electrical resistivity tomography to analyse the electrical properties of the subsurface soil and determine the vulnerable area of the landslide. The result indicated that the area is divided into high resistivity at the top of the soil and low resistivity below. These high resistivity numbers are caused by pyroclastic flow while the lower one is caused by fracture-filled,...
Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics, 2015
We report on the results of geological, geotechnical and geophysical surveys for the characterization of a landslide, occurred in the Asti Reliefs (NW Italy) during the first ten days of March 2011, just after an exceptional meteoric event. The investigated landslide is located in San Damiano d'Asti (15 km E of Asti) and involved a hilly side, gently sloping. The hazard situation in this area regards a landslide that involved the back of a building. This landslide was caused by excavations made in the time at the toe of the slope with the aim to extend the narrow flat spaces. The contribution given by Electrical Resistivity Tomography (ERT) was essential, in the first phase of the investigation, to recognize deep and localized water seepage, otherwise undetectable. The identification of saturated clays into the slope allowed us to design the correct re-profiling of the scarps and make digging operations in safety. The use of these methods of investigation has a significant economic savings in the choice of interventions for slope stabilization.
Near Surface 2009 - 15th EAGE European Meeting of Environmental and Engineering Geophysics, 2009
Geoelectrical techniques, such as resistivity and self-potential are being increasingly applied to study the hydraulics of landslide processes. The great strengths of these techniques are that they provide spatial or volumetric information at the site scale, and are sensitive to hydraulic changes in the subsurface. In this study we described the development and installation of an automated time-lapse electrical resistivity tomography (ALERT) system on an active landslide at a site near Malton, North Yorkshire, UK. The overarching objective of the research is to develop a 4D landslide monitoring system that can characterise the subsurface structure of the landslide, and reveal the hydraulic precursors to movement. In this paper we describe the installation of the ALERT system on an active landslide, and present initial results showing the 3D structure of the landslide and subsurface resistivity variations that occurred between static conditions and an active phase of slope failure.