| Summary: | The material characteristics and formation mechanism of the platform at the back edge of the Sichuan—Tibet Highway 102 Landslide were examined by many scholars. The 102 Landslide is thought to develop in the Quaternary unconsolidated accumulation platform composed of huge thick moraine and alluvial sediments. On the platform, the basis for supporting the above conclusions is slightly insufficient, and evidence such as deep hole data and geophysical prospecting results are lacking. There is no doubt about the large moraine platform existing at the same time on the front and rear edges of the 102 Landslide located in the deep mountain valley area. Based on the collection, sorting and analysis of previous research results on the 102 Landslide, this paper compares the results obtained from the adjacent and similar platforms in the main ditch of the Parlung Zangbo by analyzing comprehensive engineering geophysical prospecting and the results of the 102 tunnel survey during its construction period. Drilling data and comparative analysis of the characteristics of typical glacial deposits indicate that the platform material at the rear edge of the landslide is mainly moraine. The point of view is proposed that the material compositions of the platform are slope deposits and alluvial sediments plus the broken rock ancient landslide body. The front slope of the ancient landslide body gradually decreases in stability under the influence of such factors as groundwater, rainfall, erosion by the Parlung Zangbo and the construction of the Sichuan—Tibet Highway. Vibration, mechanical vibration, earthquake and other factors induced the resurrection of the ancient landslides, namely, the formation of the 102 Landslide. By further studying the material characteristics and formation mechanism of the platform at the rear edge of the 102 Landslide, we can better understand the geological history of southeastern Tibet, which is of reference significance and economic value for the research and prevention of similar landslides in southeastern Tibet.
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