Distribution Characteristics of Geohazards Induced by the Ludian Earthquake on 3 August, 2014 and a Comparison to the Jinggu and Yingjiang Earthquakes

On 3 August 2014, a M _s 6.5 earthquake occurred near the city of Zhaotong in Ludian County, China. The earthquake caused 617 deaths and triggered more than 1700 geohazards, most notably the large Hongshiyan, Wangjiapo, and Ganjiazhai landslides. In 2014, the Jinggu (M _s 6.6) and Yingjiang (M _s 6.1) earthquakes also occurred in the same region. In this study, the authors compared the relationships between geohazards and earthquake magnitude, fault activity, geomorphology, slope angle, seismic intensity, and population density in the three earthquakes areas. In addition, the concept of “dry” landslides is proposed. Some of the conclusions are as follows: (1) The number of geohazards significantly increased after the Ludian earthquake; (2) Large-scale landslides are controlled by active faults; (3) There is a strong correlation between topographic elevation at which geohazards occur and microtopography; (4) Slope angles in the Ludian earthquake area are significantly steeper than in the Jinggu and Yingjiang earthquake areas, with slope angles being a key factor for landslide development; (5) Mountains, canyons, rivers, river terraces, and towns are interdependent in southwestern China, which means that post-earthquake reconstruction must pay attention not only to seismic issues, but also consider geohazard prevention and geological environmental safety.