DEVELOPING CHARACTERISTICS AND EVOLUTION PROCESS OF GANJIAZHAI LARGE SCALE LANDSLIDE IN LUDIAN 8.03 EARTHQUAKE AREA OF NORTHEAST YUNNAN

At 16:30 on August 3, 2014, an M_S 6.5 earthquake happened in Longtoushan Town, Ludian County, Zhaotong, in Yunnan Province, and caused 617 deaths and triggered a large number of geohazards. The Hongshiyan landslide and Ganjiazhai landslide are notable for their largest scales in mass and many casualties. According to field survey and remote sensing image interpretation of Ganjiazhai landslide by authors, the developing characteristics and evolution periods of landslides mass are analyzed, and the key triggering factors of this landslides are studied from the perspective of active fault rupture. The Ganjiazhai landslides can be divided into two occurred times. The latest landslide mass is of 700m and 250m in length and width, and 690, 000m² and about 8.7million m³ of landslides mass area and volume, respectively. It is triggered by the Ludian earthquake from the ancient landslide or avalanche that occurred about 20kaBP, and these two occurred times were all controlled by Xiashuigou Holocene faul that extended by NW direction. At last, this article suggests preventing the risks of landslide in further in Ludian earthquake area, and should strengthen to study the recurrence period of Zhaotong-Ludian active faults in the region, in order to provide the basis for geological environmental safety in the geohazards reconstruction after the earthquake.