Geophysical Model and Displacement of Active Landslide—An Example from Jastrzębia Góra Cliff (Northern Poland)

Abstract

Digital photogrammetric analysis and electrical resistivity tomography (ERT) techniques were used to identify the structure of the landslide and determine its dynamics in Jastrzębia Góra cliff (northern Poland). Two photogrammetric high-resolution models were generated from airborne laser scanning data and compared. The first model came in 2010 while another in 2013. This way, the displacement of the surface of the landslide was analyzed. The differences between the grids points of digital elevation models were used for determination of vertical movements and calculation the volume of displaced rock masses. The differences were visualized as a shaded relief map. Digital model derived from airborne laser scanning can determine the precise extent of the landslide and primary and secondary scarps and provide many landslide morphometry data. The advantage of this method is the ability to filter data and therefore to eliminate the vegetation. Interpretation of relief on the digital elevation model can efficiently speed up field work and thus reduce the cost of research. In order to identify the geological structure of the cliff and the landslide structure we used geophysical method of electrical resistivity tomography. For this purpose, we made five geophysical profiles on the landslide. To detect the sliding surface and estimate the thickness of the sliding material, several transversal and longitudinal ERT profiles were collected. The resistivity images of subsurface obtained from ERT data and supported by stratigraphic and lithological data from boreholes were integrated with the information from the DEMs. As a result the geological structure of the landslide was examined and the depth of the slip zone was determined.