## 3 Study Area
### Deformation Characteristics  
To protect the safety of the residents below the landslide, we completed the deployment and commissioning of monitoring equipment to establish a monitoring and early warning system on 15 April 2021. The location and photos of the monitoring stations are shown in Figure 2. Two GNSS monitoring stations, named DB01 and DB02, were deployed on the main slide profile of the landslide, and the GNSS base stations are located on the roadside of the lower side of the landslide. In addition, a rain gauge named YL01 was deployed at DB02. The automated monitoring system received the first monitoring data at 17:00 on 15 April, and the default acquisition interval of the GNSS monitoring stations was 1 h. As the landslide appeared to accelerate significantly on 17 May, the GNSS monitoring stations adjusted the collection interval to 30 min, and the collection interval of the rain gauge was adjusted to 20 min. As of 15:00 p.m. on 1 July 2022, a total of 57,597 monitoring data were collected by the monitoring system, including 30,396 GNSS monitoring data and 27,201 rainfall monitoring data. The monitoring data are shown in Figure 3.  
From Figure 3, it can be seen that the deformation patterns of the two GNSS monitoring stations are basically the same, but the deformation amplitude of DB02 is significantly larger than that of DB01, which indicates that the deformation of the leading edge of this landslide is larger than that of the trailing edge of the landslide, which is consistent with the deformation characteristics of the traction landslide. The threshold design and warning process of this landslide are described in [PERSON] et al. [16] The deployed monitoring and warning system is able to accurately and quickly identify the accelerated deformation process of the landslide and report timely warnings. To verify the reliability of the monitoring data,  
Figure 2: Geographical location and monitoring scheme of Lishanyuan landslide. **(a)** Site photograph of the Lishanyuan landslide. **(b)** Geographical location of the Lishanyuan landslide. **(c)** Photographs of monitoring stations DB02 and YL01. **(d)** Photograph of the DB01 monitoring station.  
we inspected the landslide site on 19 May 2021. At this time, the landslide area had just experienced a strong rainfall, and the monitoring data from two GNSS monitoring stations showed that the landslide had been violently deformed. We found multiple cracks in the landslide body during a site inspection (Figure 4), obvious slippage, soil accumulation at the foot of the slope, and small mudslides in the local area. These macroscopic phenomena are consistent with the monitoring and early warning results, proving the effectiveness and reliability of the monitoring and early warning system.  
The deformation process of Lishanyuan landslide shows obvious correlation with the rainfall process. Taking the DB02 monitoring station with the most obvious deformation as an example, the displacement of the two GNSS monitoring stations first showed a fluctuation of 10 mm for about a week after the monitoring started, indicating that the measurement accuracy of GNSS was of centimeter level. Affected by the rainfall event on 22 April 2021, the acceleration process began with the synchronization of the displacements of the two GNSS monitoring stations starting at 4:00 a.m. on 23 April. After that, the displacements of the two monitoring stations showed a step-like growth, and each severe deformation process was accompanied by concentrated high-intensity rainfall. After mid-October, the rainfall decreased, and the deformation began to slow down, showing creep characteristics. After April of the following year, the landslides started a process of obvious deformation and acceleration again.