Studying the Fracture System of a Landslide by ERT Method

In contrary to former researches which used to stud y the sliding surface or the water content of certain layers of a landslide area we investigat ed the near-surface fracture system of it. It makes possible the delineation of the endangered ar ea and gives information about the inner structure of the landslide. For this aim Electrica l Tomography (ERT) measurements were carried out by different geoelectric configurations . Due to the different conditions of the fractures they can be both conductive and resistive ones and even it is possible that a part of them is conductive while the remaining part is resi stive in the function of the filling material and the time passed since the last rainfall. This f eature and the probably high density of the fractures make the interpretation of the ERT data r ather difficult. The Schlumberger and especially the Dipole-Dipole results proved to be a lmost inutile, while the Pole-Dipole and especially the Stummer array results seem to be muc h more perspective. The results of these arrays were compared to the Pressure-Probe data we got on the same profile. Using the ERT results a lot of fractures were detected and more o r less well localised and on the basis of the fractures the research area could have been divided into several domains which are differently fractured. It emerged among others that even in the not-yet sliding area there are fractures that is a part of this area tends to be m ore and more dangerous, as well.