In-situ Time-lapse Geophysical Monitoring for Rain-induced Landslide Forecasting

Rain-induced landslides pose a global threat, resulting in significant casualties and infrastructure damage annually. Such impacts can be reduced utilizing efficient early warning systems to plan mitigation measures and protect vulnerable elements. This study presents an innovative geophysical monitoring approach that combines electrical resistivity tomography (ERT) and quasi-distributed opto-electronic sensing (OES), deployed on a clay rich slope typical of thousands in the Greater Bay Area, China. ERT is used to generate detailed dynamic resistivity maps, combined with OES-indicated moisture content, highlighting the spatial-temporal distribution of slope-scale moisture content. The relationship between the analytical solution of Factor of safety informed by ERT-derived dynamic moisture maps and contemporaneous landslide displacement is confirmed by quasi-distributed OES strain measurements. By revealing the connection between landslide movement and ERT-OES-informed slope stability, this combined ERT and OES monitoring approach offers new insights into landslide mechanisms. Our study demonstrates the importance of relying on multi-source observations to develop effective landslide risk management strategies and accents the advantages of incorporating subsurface geophysical monitoring techniques to enhance landslide early warning approaches.