Characterisation of Landslide using InSAR Technique and Electrical Resistivity Method at Paya Terubong, Malaysia

Abstract

Ground movement is common around hilly areas; as such, there is a need to investigate the activities of the ground surface and subsurface of such regions. This research presents an application of the Permanent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique and electrical resistivity (ER) method for the measurement of ground deformations and investigation of the subsurface features, respectively, at Paya Terubong, Penang Island. The PS-InSAR is an instrument for detecting patterns of deformation over a wide region, while the ER approach is used to image subsurface characteristics and measure the resistivity of the rock formation. Satellite data obtained from Sentinel-1A (S-1A) were used to detect some active ground deformation zones. The velocity of − 41 mm/Yr was discovered along the line of sight (LOS) of the system, indicating subsidence. An ER survey was performed at the topsoil within 5 m depth based on the ground deformation patterns detected through the InSAR technique. Two-dimensional (2-D) resistivity lines were laid using the ABEM SAS4000 Terameter and a dipole–dipole array with an electrode spacing of 2.5 m. The areas with low values of resistivity ranging between 0 and 20 Ωm were classified as saturated zones. The efflux and influx of subsurface water when the layers of rocks are lubricated and downcutting of steep slopes are among the suspected causes of deformation. The application of the two techniques has improved the understanding of both the surface and subsurface mechanisms, reduced variation in the results, and allowed the investigation of active landslide areas.