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The 2015 Gorkha Earthquake in Nepal and the 2008 Wenchuan Earthquake in China occurred at the south and southeast margins of the Tibetan Plateau, respectively. Both earthquakes had similar magnitudes of Mw 7.8 and 7.9, caused catastrophic loss of life and damage to property, and generated tens of thousands of landslides. Comparisons of pre-and post-quake satellite images supported by field investigations show that the Gorkha Earthquake triggered at least 2 064 large landslides (defined as covering an area ≥10 000 m 2 ) over a ~35 600 km 2 region with a volume of (444-584)×10 6 (average 509×10 6 ) m 3 and total area of 44.78×10 6 m 2 . In contrast, the Wenchuan Earthquake triggered 25 580 large landslides over a region of ~44 000 km 2 with a volume of (7 128-9 479)×10 6 (average 8 219×10 6 ) m 3 and a total area of about 670.65×10 6 m 2 . Several controlling factors including topographic relief, slope steepness, and regional peak ground acceleration (PGA) were investigated to try to explain the great differences between the number, volume and area of the coseismic landslides associated with the two similar earthquakes. We found that the differences primarily arose from an unexpected factor, the dip angle of the seismogenic fault. This discovery should aid understanding the failure mechanisms of quake-triggered landslides, and suggests that more factors should be taken into consideration in estimating coseismic landslide volumes from earthquake magnitudes.

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Landslide-dammed lake outburst floods (LLOFs) may pose serious safety threats to nearby residents and their livelihoods, as well as cause major damages to the downstream areas in mountainous regions. This study presents the Diexi ancient landslide-dammed lake (DALL) in the Upper Minjiang River at the eastern margins of the Tibetan Plateau, which was known to an estimated previous maximal lake area of 1.1 × 10 7 m 2 and an impounded volume of 2.9 × 10 9 m 3 . Then, at approximately 27 ka BP, the ancient landslide dam failed and catastrophic LLOFs occurred. It was determined that the peak discharge of the Diexi ancient LLOFs could be reconstructed using regression, parametric, and boulder competence approaches. The reconstructed maximum peak discharge might be 72,232.66 m 3 /s, with an average velocity of 17.23 m/s, indicating that the Diexi ancient LLOFs were the most gigantic outburst floods to