Three-rivers basin, which spans the deeply incised southeast Tibetan Plateau and north Tibetan Plateau with a low relief surface, is characterized by highly varied topography and climate, strong neotectonic movement and frequent seismicity, leading to fragile geological conditions, frequent occurrence of geohazards, and resulting in remarkable hazard chains. This severely threatens the safety of local residents and engineering constructions, and normal operation of infrastructures. Based on the landslide hazards interpreted from GoogleEarth, the characteristics of landslide hazards in Three-rivers basin were analyzed. The GoogleEarth images were adopted to map the types and spatial distributions of landslide hazards. The results were verified with limited field reconnaissance. The SRTM digital elevation model (DEM) data with a resolution of 90 m were used to analyze the terrain parameters, including elevation, slope angle, slope aspect, and relative relief. The lithological groups were compiled from 1:500000-scale geological maps based on detailed lithological descriptions. The grid layer of distances to major faults was buffered from the main faults of 1:500000-scale geological maps, compiled with the major faults obtained from 1:1500000-scale tectonic map of Tibetan Plateau and neighboring region, in which the tectonic units were also extracted. All vector layers were rasterized and reclassified together with the raster layers, and then overlaid with the spatial distribution of landslide hazards. Percentage of landslide area (PLA) was used to create histograms and statistically analyze the significance of the factors influencing the occurrence of landslide hazards, based on geographic information system (GIS) method. A total of 60 315 landslides with an area of not less than 0.001 km2 for single landslide, including slides, rockfalls and deforming bodies, were mapped in the Three-river basins with an area of about 462 000 km2. Landslide hazards were mostly slides in type, accounting for 97.73% of the total, and characterized by banded densely distribution along the deeply incised valleys with local differentiation, and densely distribution along some major faults, e.g. Batang fault, Weixi—Qiaohou fault, and Lawa—Wangdalong segment of Suwalong—Xiongsong fault. For terrain parameters, landslide hazards mostly occurred on the slopes with angle ranging from 20° to 30°, elevation varying from 800 m to 4 000 m, and local relief exceeding 1 000 m. Among the 18 lithological groups, the following 5 groups, clastic rock and slate intercalated with limestone, mudstone and shale and siltstone, ophiolitic mélange, phyllite and slate, volcanic rocks, were mostly prone to slope failure. Among the 25 tectonic units, the following 7 units, including Jinsha River ophiolitic mélange, Zhongza limestone terrane, Yanyuan—Lijiang Continental margin rift basin, Naqu—Luonong forearc basin, north Lancang River ophiolitic mélange, Baoshan Terrestrial sea basin, and Ganzi—Litang ophiolitic mélange, were more vulnerable to landslide hazards. Although slope aspect and distance to major faults might have some influences on the landslide hazards, the role was not significant. Landslide hazards were densely distributed in Three-rivers basin of southeast Tibetan Plateau. The terrain and geological parameters significantly influencing the occurrence of landslide hazards consist of slope angle, elevation, relief, lithological group, and tectonic unit. Both slope aspect and distance to major faults have little impact on the landslide hazards. Copyright ©2020 Advanced Engineering Sciences. All rights reserved.
