Groundwater seepage plays a critical role in the long-term safety of high-level radioactive waste (HLW) disposal, yet its characterization remains challenging due to the complexity of fractured rock media. This study introduces the Double-Layered Seismo-Electric Method (DSEM) for imaging groundwater seepage fields with enhanced sensitivity and spatial resolution. By integrating elastic wave propagation with electrokinetic coupling in a stratified framework, DSEM improves the detection of hydraulic gradients and preferential flow pathways. Application at a representative disposal site demonstrates that the method effectively delineates seepage channels and estimates hydraulic conductivity, providing reliable input parameters for groundwater flow modeling. These results highlight the potential of DSEM as a non-invasive geophysical technique to support safety assessments and long-term monitoring in deep geological disposal of high-level radioactive waste.

Landslide fracture zones play a critical role in slope instability, yet their hydraulic fracturing processes remain difficult to monitor using conventional geophysical methods. This study proposes a time‐lapse three‐dimensional transient electromagnetic (TEM) imaging approach to characterize fracture damage evolution in the Xiaolongdong–Xiahaizi landslide, Zhaotong City, China. Repeated TEM observations, integrated with GNSS displacement monitoring and environmental measurements, were used to reconstruct dynamic resistivity fields through three‐dimensional inversion. The method achieved localization accuracies better than 1 m horizontally and 2 m vertically and detected water‐filled fractures wider than 0.3 mm. Distinct resistivity precursor anomalies, characterized by a 3%–8% increase followed by a rapid decrease, occurred 2–5 min before fracture propagation. During hydraulic fracturing, resistivity decreased from 30–50 Ω·m to 8–15 Ω·m, reflecting progressive fracture connectivity. Rainy‐season permeability coefficients reached 10⁻⁴–10⁻³ m/s, one to two orders of magnitude higher than those during the dry season. Freeze–thaw processes and rainfall infiltration jointly contributed 25%–35% of slope displacement. The proposed framework provides quantitative visualization of fracture evolution and effective geophysical constraints for landslide stability assessment and early warning.

Landslide fracture zones play a critical role in slope instability, yet their hydraulic fracturing processes remain difficult to monitor using conventional geophysical methods. This study proposes a time-lapse three-dimensional transient electromagnetic (TEM) imaging approach to characterize fracture damage evolution in the Xiaolongdong landslide, Zhaotong City, China. Repeated TEM observations, integrated with GNSS displacement monitoring and environmental measurements, were used to reconstruct dynamic resistivity fields through three-dimensional inversion. Distinct resistivity precursor anomalies were characterized by a 3–8% increase followed by a rapid decrease. During hydraulic fracturing, resistivity decreased from 30 to 50 Ω·m to 8–15 Ω·m, reflecting progressive fracture connectivity. Rainy-season permeability coefficients reached 10⁻⁴–10⁻³ m/s, one to two orders of magnitude higher than those during the dry season. A substantial proportion of the observed displacement occurred during periods characterized by seasonal temperature fluctuations and rainfall-related hydrological changes. However, the available observations do not permit a quantitative separation of the contributions of freeze–thaw processes, rainfall infiltration, gravitational creep, and other driving mechanisms. Time-lapse TEM observations revealed substantial temporal variations in the resistivity structure of the landslide fracture zone. The development and spatial connectivity of low-resistivity anomalies were associated with seasonal hydrological changes, indicating the potential of repeated TEM surveys for characterizing subsurface moisture redistribution and fracture-zone evolution. However, the temporal resolution of the available TEM surveys does not permit identification of minute-scale precursory signals. The proposed framework provides quantitative visualization of fracture evolution and effective geophysical constraints for landslide stability assessment and early warning.