Mechanisms of glacier surges in the Central Himalayas uncovered using remote sensing and glacier modelling

Glacier surges are a primary trigger for various glacial hazards, including ice avalanches, glacier collapses, and glacial lake outburst floods. This study systematically examines the characteristics and subglacial processes of an unnamed glacier in the central Himalayas, leveraging high temporal resolution remote sensing data and glacier modelling. We identify a surge event that began in 2019 and persisted for less than eight month, marked by rapid acceleration and deceleration phases. During the surge, >0.23 km³ of ice was transferred from higher to lower elevations, resulting in a thickness increase exceeding 70 m at the glacier terminus and an advance of over 800 m. This was accompanied by extensive crevasse formation across a larger surface area compared to pre-surge conditions. Our analysis quantitatively characterizes changes in basal stresses, strain rates, and sliding velocities, revealing that the surge was predominantly driven by subglacial sliding facilitated by surface meltwater infiltration. Regional climate fluctuations acted as external drivers, disrupting the glacier's dynamic equilibrium and triggering the surge, which was governed by a hydrological switch mechanism.