Landslide Warning Announcement Heifangtai Guoxia Town People's Government 23 Sept. 2017 GNSS (c) Dangchuan 4# Crackmeter Piezometer Rain Gauge 0 0.5 1 (km) Gansu Province (a) At 20 h 55 min Message Delivered to Government Accumulated Displacement (mm) 1,200 1,050 900 750 600 450 300 Displacement Rate (mm/d) 150 1 Aug. 12 Aug. 23 Aug. 3 Sept. 14 Sept. 25 Sept. Failure at 5 h 1 Oct. 30 27 24 Red Warning at 17 h 50 min 17 s 30 Sept. 21 18 Yellow Warning 15 Orange Warning on 23 Aug. 12 on 27 Sept. 9 6 3 0 1 Aug. 12 Aug. 23 Aug. 3 Sept. 14 Sept. 25 Sept. Yellow Warning Orange Warning (b) 6 Oct. Red Warning at Dangchuan Area! Landslide May Occur Since 1 Oct. (d) 8h Failure at 5 h 1 Oct. 6 Oct. Red Warning (e) FIGURE 3. The landslide warning at Dangchuan 4# landslide in Heifangtai, China. (a) The location of Dangchuan 4# landslide with various in situ sensors. (Source: Google Earth; used with permission.) (b) The cumulative displacement and displacement rates from a crackmeter installed across the trailing head scarp edge during the period from 1 August 2017 to 1 October 2017. (c) A photo of the Heifangtai landslide warning announcement from 23 September 2017, which was posted on a pillar in Guoxia town by the local government. (d) The red warning message delivered to the local government through the WeChat app at 20:55 on 30 September 2017. (e) The postfailure photo of the Heifangtai landslide (Dangchuan 4# slope), which failed at 05:00 on 1 October 2017. (Source: SKLGP; used with permission.) MARCH 2020 IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE 141