The South Lhonak lake in the Himalayan state of Sikkim breached on the night of October 3, resulting in a glacial lake outburst flood (GLOF) that ravaged four districts. At least 42 people died as a result and 77 more are still missing. More than a month after the disaster, the lake remains a potential hazard, say scientists.
The South Lhonak lake is located in North Sikkim, at an altitude of 5,200 m. According to scientists, the current interpretation of the flood – which relies heavily on satellite data – suggests that on October 3 night, a slope failure occurred along the lateral moraine (a mass of debris and rocks) on the lake’s left bank. Preliminary research found that some of the landslide material scraped the glacier terminus; most of it hit the lake, creating an impulse wave that moved towards the lake’s narrow front end.
