<b>Precursor</b><b>s</b><b> of the 2026 Nepal rock–ice avalanche</b><b>: </b><b>differentiated deformation</b>

Here we combine ascending- and descending-track Sentinel-1 interferometric synthetic aperture radar (InSAR) observations from 2015–2026 with NISAR L-band polarimetric data to reconstruct the complete pre-failure evolution of the source slope. We show that the rock-ice avalanche mass(RIAM) became internally fragmented following the 2015 Gorkha earthquake, and that the maxima of both deformation and fracturing coincide at the ice–rock junction.

Then, differential acceleration within the RIAM emerged two years before the collapse, synchronous with anomalously high air temperatures. This precursory signal extends the warning window for ice–rock avalanches to several years and provides a transferable observation framework for the early detection of high-mountain Asian cryospheric hazards under global warming.</p>