Preprints
https://doi.org/10.5194/egusphere-2023-2253
https://doi.org/10.5194/egusphere-2023-2253
12 Dec 2023
 | 12 Dec 2023
Status: this preprint is open for discussion.

Seismic Deformation of Himalayan Glaciers Using Synthetic Aperture Radar Interferometry

Sandeep Kumar Mondal, Rishikesh Bharti, and Kristy F. Tiampo

Abstract. The Himalayan belt, formed due to Cenozoic convergence between the Eurasia and Indian craton, acts as a storehouse of large amounts of strain that results in large earthquakes that occur from the western to the eastern Himalayas. Glaciers also occur over a major portion of the high-altitude Himalayan region. In this study, we attempt to understand the impact of earthquakes on and around Himalayan glaciers in terms of vertical deformation and coherence change. Eight earthquake events of various magnitudes and hypocenter depths occurring in the vicinity of Himalayan glacial bodies have been analyzed using C-band Sentinel1-A/B synthetic aperture radar (SAR). Differential interferometric SAR (DInSAR) method is applied to the pre-and co-seismic single look complex (SLC) SAR imagery to capture glacial surface deformation potentially related to earthquake occurrence. The influence radius of each earthquake (Mw>4.5) is defined using shake maps. For the lower magnitude earthquakes (Mw<4.5), influence radii are computed using the linear relationship between influence radii and magnitudes of past earthquakes. The mean glacial displacement varies from -38.9 mm to -5.4 mm for the 2020 Tibet earthquake (Mw 5.7) and the 2021 Nepal earthquake (Mw 4.1). However, small glacial and ground patches processed separately for vertical displacements reveal that the glacial mass shows much greater seismic displacement than the ground surface. This indicates potential site-specific seismicity amplification properties of glacial bodies that need additional studies. Reduction in co-seismic coherence around the glaciers is observed in some cases, indicative of possible changes in the glacial moraine deposits and/or vegetation cover. The effect of two different seismic events (the 2020 and 2021 Nepal earthquakes) with different hypocenter depths but the same magnitude at almost equal distances from the glaciers is assessed; a shallow earthquake is observed to result in a larger impact on glacial bodies in terms of vertical displacement. Earthquakes may exacerbate or induce glacial hazards such as glacial surging, ice avalanches, landslides and failure of moraine-/ice-dammed glacial lakes. This research can assist in identifying areas at risk and provide valuable insights for planning and implementing measures for disaster risk reduction in the near future.

Sandeep Kumar Mondal, Rishikesh Bharti, and Kristy F. Tiampo

Status: open (until 27 Mar 2024)

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Sandeep Kumar Mondal, Rishikesh Bharti, and Kristy F. Tiampo
Sandeep Kumar Mondal, Rishikesh Bharti, and Kristy F. Tiampo

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Short summary
This study explains the capabilities of C-band Synthetic Aperture Radar (SAR) system in detection of glacial deformation due to earthquakes. Due to the remote location of the Himalayan glaciers associated with harsh weather conditions and rugged topography, the method of differential interferometric SAR (DInSAR) can be very useful in studying the impact of earthquakes in the glaciated regions where field-based seismological study is extremely tough to execute.