Glacier Surge in Central Himalaya: A topographical surprise

Abstract

Abstract Our understanding of glacier dynamics and climate variability in the Himalaya exhibits significant gaps and heterogeneity. In this study, high-resolution LISS-IV (2011, 2017, 2020) and Cartosat-1 (2011, 2012) PAN images with Landsat data in conjunction with SRTM, ASTER, and High Mountain Asia (HMA) digital elevations models (DEMs) were used to understand the surge behaviour of an unnamed glacier in central Himalaya. Based on observations of the glacier terminus fluctuation, area change, surface ice velocity (SIV), and surface elevation change from 2000–2022, a study revealed that an unnamed glacier exhibited surge behavior. Glacier's SIV increased from 2000–2020 and is declining after the surge. The SIV was 7.21 ± 3.01 m/yr in 2001-02 and 163.32 ± 0.60 during October 2019-20. In September-October 2019, there was a sudden and significant increase in SIV to 863 meters within a month, indicating the surging behaviour of the glacier. Overall, the results suggest that the glacier's velocity varied considerably during the observed period, with periods of gradual increase, sudden increase, and significant decrease. Further, the glacier surface elevation change suggests an overall mass gain of 0.26 ± 0.27 m/yr from 2000-20, with a temporary mass loss of -0.13 ± 0.41 between 2011 and 2015. In addition, two earthquakes, measuring 3.5 and 3.3 in magnitude, occurred near the glacier on March 9th, 2018, at midnight (12:06 AM) and morning (4:29 AM), respectively. We assumed that these events may have impacted to glacier's base, which had previously rested on sedimentary rocks. This, combined with glacier melting and subsequent earthquakes in 2018, likely altered the glacier's velocity threshold, leading to a surge. In this paper, we present a novel observation of a glacier surge in the central Tethyan Himalaya and attempt to identify the underlying processes driving the surge. This study represents the first reported occurrence of a glacier surge in the central Himalaya.