LAUSR

On 12 July 2018, the giant Jiangdingya ancient landslide reactivated and blocked the Bailongjiang River in Nanyu Town, Gansu Province, China. The ancient landslide was ca. 4.1~4.9 × 10 7  m 3 , and the 2018 reactivated landslide was ca. 4.8~5.5 × 10 6  m 3 , with the characteristics of a deep-seated retrogressive landslide. The terrain and geological structure of the landslide area are very complicated with alpine valleys and high gradient rivers, and the ancient landslide had maturely developed. The Pingding-Huama fault, which has been active since the late Quaternary, passed through the landslide region. Because of the active fault and tectonic uplift, the lithology is deeply fragmented. Based on the remote sensing interpretation and field investigation, development characteristics and reactivation mechanism of the Jiangdingya ancient landslide are described.