On 16 August 2024 at 13:25 NPT (Nepal Time), a glacial lake outburst flood (GLOF) occurred upstream of Thame Village in the Solukhumbu District, Nepal, resulting in the destruction of 14 houses and affected 135 people. To identify the source of the disaster and gain an in-depth understanding of its triggering mechanisms and evolutionary process, this study utilized multi-source remote sensing data, including 15 optical images and 49 SAR images acquired before and after the event, to determine the precise location of the outburst glacial lake and analyze its spatiotemporal dynamics. The time series optical images results indicate that the Ngole glacial lake group consists of five glacial lakes, with overflow from the Upper Nogle Cho (glacial lake #5) identified as the key factor triggering the outburst of the Lower Nogle Cho (glacial lake #4). Further analysis using SBAS-InSAR technology detected four unstable slopes upstream of the Upper Nogle Cho, indicating that persistent potential mass movements continue to pose a GLOF risk. The study reveals that the flood event in Thame Village represents a typical mass movement triggered glacial lake outburst flood, following a disaster chain pattern of ‘mass movement - glacial lake outburst -debris flow.’ Based on this inspiration, this paper proposed a novel large-scale hazard assessment method for mass movement triggered glacial lake outbursts, integrating time-series InSAR technology and slope unit division as core components. This method was applied to evaluate the outburst hazard potential of mass movement triggered glacial lakes across an area of 3,600 km², covering 410 glacial lakes and 10 glacial lakes identified as high hazard. This study not only enhances the understanding of the outburst process in Thame valley but also provides a systematic methodology for large-scale hazard assessment of similar hazards in high-mountain regions.
 

glacial lake outburst flood; mass movement; InSAR; hazard assessment; slope unit