Precursory indications of movement for the 26 August 2026 Langtang Lirung landslide in Nepal

Satellite imagery from Planet Labs revealed few signs of impending failure before the Langtang Lirung landslide on 26 August 2026. The catastrophic event originated from a large rock slope failure on the flanks of Langtang Lirung, a massif in Nepal's Langtang National Park. Two days of imagery (12 and 25 August 2026) were available for analysis.

While the imagery provided moderate spatial resolution, it was likely used for detecting precursory signs of failure, if an optical approach was employed. Two comparison images were provided, one from 12 August 2026 and one from 25 August 2026. On first inspection, there was little apparent change between the two images, with differences attributed to shadows, clouds, and other irrelevant factors.

However, a closer look revealed two significant changes. Firstly, the ice near the landslide's crown had moved, indicating a possible change in the area. Secondly, there were signs of increased rockfall activity in the midslope region, visible in the following satellite image. This change signified the detachment of several rock slope parts, with large boulders collecting below, suggesting the debuttressing of the upper slope and likely playing a role in the landslide's failure.

Despite these minor changes, they were likely difficult to differentiate from the background level of activity. The article acknowledges the assistance of Planet Labs for providing the imagery and encourages further investigation into the landslide's precursory signs.