## 2 Fast Deploying Monitoring System
### FDMS in Bage Landslide  
In the early morning of 11 October 2018, a large scale landslide occurred on the Tibetan Bank of the Jinsha River at the junction of Baige Village, Boro Township, Jiangda County, Tibet Autonomous Region and Zeba Village, Ronggai Township, Baiyu County, Sichuan Province. The landslide blocked the Jinsha River and formed a barrier lake. Then, late on November 3, a second landslide occurred and blocked the Jinsha River again. The location of the landslide is shown in Figure 4. Figure 5 shows a photograph of the Baige landslide and the details of the sliding surface. In Figure 5, a fault extending along the road at the back of the landslide can be seen. On the top of the landslide, the white/green cataclastic serpentine is exposed, and its thickness is about 300 m. The serpentine is mainly located in the up area of the landslide, between the elevations of 3400-3700 m. Below 3400 m, Gneiss is exposed (Figure 6). The dip direction and the dip are 235\({}^{\circ}\) and 40\({}^{\circ}\), respectively. There are two structural planes in the side of the landslide. The dip direction and the dip of one plane are from 60\({}^{\circ}\) to 80\({}^{\circ}\) and from 75\({}^{\circ}\) to 85\({}^{\circ}\), respectively. The other are 100\({}^{\circ}\) to 115\({}^{\circ}\) and 80\({}^{\circ}\). Because of the two structural planes, which formed during the landslide, a wedge-shaped groove which is thick in the middle and thin in  
Figure 3: Working mode. Normal mode (**a**), Communication fault mode (**b**), and Beidou satellite communication mode (**c**). Figure 2: Fast deploying monitoring system. the sides was formed. The average slope length of the landslide was about 790 m and the width was about 500 m. The average thickness of the landslide was about 50 m and the maximum thickness may have been 80 m (Figure 5). In the first landslide, there were approximately \(2.2\times 10^{7}\) m\({}^{3}\) of rock and soil that fell into the Jinsha River and built a dam in the valley. Then, a barrier lake was formed by the dam (Figure 5). The length of the barrier lake was about 1100 m, and the width was about 500 m. The maximum height of the dam over the original river surface was about 85 m. The second landslide occurred at the back edge of the first landslide. In this case, the total volume of the rocks falling down were about \(8.5\times 10^{6}\) m\({}^{3}\). The unstable rock mass scraped the broken rock mass along the way, which added \(0.8\times 10^{6}\) m\({}^{3}\) more rock falling down. The rocks blocked up the Jinsha River again and increased the height of the dam formed in the first landslide by 50 m [31]. The barrier lake formed by the two landslides was a great threat to the people living in the lower reaches of the Jinsha River. The Baige landslide occurred suddenly. There were no monitoring devices working there previously. There were also no mobile signals. A monitoring system needed to be set up immediately to ensure the safety of the emergency rescue workers dredging the barrier lake. Thus, the FDMS was applied there. The locations of the monitoring equipment are shown in Figure 7. BD1, BD2, BD3, and BD4 represent the Beidou receivers, while CM1, CM2, CM3, and CM4 represent the crack meters. The equipment was located in the back edge of the slope to monitor the movements of the landslide. In this FDMS, the surface displacements were measured by Beidou receivers and the crack widths by the crack meters. The sampling time step was 10 min. The Beidou receivers were Northdoo global navigation satellite system (GNSS) devices. Their plane accuracy is (8 + 1 ppm) mm, and the elevation accuracy is (15 + 1 ppm) mm. This is much better than the differential global position system (DGPS) working model, which has a plane accuracy of (3 + 1 ppm) mm, and an elevation accuracy of (5 + 1 ppm) mm.