Time-lapse monitoring on landslide properties by seismic refraction and electrical resistivity tomography methods

Landslide monitoring can characterize subsurface water percolation, hydrogeological conditions, and slope stability over time. In other words, the aim of the time-lapse method is to a better understanding of water circulation and its effect within the landslide body. In this study, spatiotemporal changes of the water content are monitored by two applied geophysical methods: ۲D time-lapse electrical resistivity tomography (TLERT) and ۲D P-wave time-lapse seismic refraction tomography (TLSRT) in Xiaoshan district, Hangzhou city, China. Time-lapse electrical resistivity is performed by the Wenner alpha array due to its ability to display high vertical resolution of subsurface images and signal-to-noise ratio. Time-lapse seismic refraction tomography is conducted as individual models corresponding to time-lapse electrical resistivity images. Good agreement between the results of the two geophysical methods can illustrate the landslide geometry and possible sliding hazard by characterizing the moisture content and changes of clay content over two different periods.