Three-dimensional CSAMT Forward Modeling of Potential Landslide Sliding Surfaces Using Finite Element Method

Landslides are a type of natural disaster that can cause substantial harm to humanity. Monitoring and predicting the initiation of potential landslides is critical to avoiding losses due to disasters and economic activities. The impact of the controlled-source audio-frequency magnetotelluric method on investigating landslide surfaces is assessed through numerical simulations with a finite element approach. A Dirichlet boundary condition is selected to match the truncated boundary, resulting in a remarkable improvement in simulation efficiency. Rederivation of the formulas for a layered medium adept to the controlled-source audio-frequency magnetotelluric method is necessary to determine the electromagnetic field at any location along the truncated boundary. After the reliability evaluation of the new codes, a landslide model with a slide surface is designed, and the characteristics of its electromagnetic field and the apparent resistivity are studied. Instead of the total electromagnetic field, which is strongly influenced by topography variation, the apparent resistivity should be used for sliding surface detection. The normalized pure anomalous electromagnetic field may also be employed to quickly assess the detectability of the sliding surface. Overall, this study demonstrates that the controlled-source audio-frequency magnetotelluric method can be employed for investigating landslides, and recommends survey parameters, including configuration, frequency range, and length of survey line in landslide exploration.