Ling Xin in the MIT Technology Review:
A massive landslide—the worst in decades—struck Du Fangming’s home in south China’s Hunan province on July 6. “My house collapsed. My goats were swept away by the mud,” he told Chinese media outlets shortly after the catastrophe. Fortunately, though, he was safe—one of 33 villagers who had been evacuated thanks to early warnings enabled by advanced positioning technologies that can provide more accurate readings than ever before.
Powered by China’s newly completed global navigation satellite system, BeiDou (“the Big Dipper”), and its ground-based stations, position sensors can detect subtle changes in the land’s surface in landslide-prone regions across China. Movement over a few meters can be spotted in real time, while post-processing accuracy can reach the millimeter level.
That means a shift in the dirt about the size of the tip of a sharp pencil can be spotted from more than 21,000 kilometers above. Twelve days before the landslide, Du’s village received an orange alert citing data anomalies, which pointed to accelerating surface sliding following days of heavy rain.