Applications of remote sensing and near-surface geophysical methods for the investigations of a morainic ridge susceptible to landslide. A case study from the high lands of the Himalayas, Pakistan

Numerous factors are necessary to comprehensively comprehend the complex phenomenon of landslides and, ultimately, facilitate effective measures for their protection and management. This paper investigates the case history of the Maicher landslide in the Nagar District (Northern Pakistan) by using a multidisciplinary combined technique approach based on conventional geophysical measurements and modern remote sensing techniques. The first technique is to identify the rate of deformations with real-time landslide monitoring sensors and satellite images. Care is devoted to data acquisition and processing using the ad-hoc methodology to minimize errors and ensure high reliability. For the second technique (electrical resistivity tomography, surface waves measurements, and ground-penetrating radar), convenient methods for landslide characterization are used and herein presented. The combination of information taken from the different techniques allows the results to be validated by con-ventional and modern approaches and enhances the accuracy of each method. The results suggest that shear surface planes at a depth of 35-40 m have developed over time. The analysis also provided information on controlling factors and possible expansion of the different slope sections. This work highlighted that geophysical parameters (shear wave velocity Vs, dielectric constant epsilon, and resistivity value rho) could provide reliable quali-tative and quantitative information about the shallow layer, bedrock contacts, possible sliding surface and subsurface water saturation, and seepage system of a landslide. The geophysical results reflect an overview of the geological model and are effective in terms of the slope stabilization process.