LoS changes of landslide surface deformation near Lete, along Kali Gandaki River, Nepal using ALOS-2 InSAR images

Abstract:

Many attentions were paid to detect landslides that block channels in the region, especially after Gorkha earthquake (25 Apr 2015; Mw7.8). Therefore, I tried to illustrate LoS (line of sight) changes of landslide surface deformation near Lete, along Kali Gandaki River after 2015 Gorkha earthquake (Mw7.8), using ALOS-2 Synthetic Aperture Radar interferometry (InSAR) images. The reason of this site selection is that geomorphological and geological characteristics was pointed out by Chigira et al. (2019) and landslide slope deformation velocity at this site has already detected by Sato et al. (2020) using Sentinel-1 SAR images processed LiCSBAS software (Morishita et al., 2020). In this study two images were produced from the ALOS-2 data by RINC software (Ozawa et al., 2016), and the data observation periods are 30 Nov 2017-24 Jan 2019 and 08 Mar 2018-24 Jan 2019 in path 158, frame 560. As a result, deformations around the summit recorded at 3.8-5.5 cm along LoS for 30 Nov 2017-24 Jan 2019 and at 3.2-3.5 cm along LoS for 08 Mar 2018-24 Jan 2019. But at the foot of the slope the deformantion amount was 1.6-2.3 cm for the both periods. This suggests that the slope deformation amount is larger around the summit than at the foot slope, and deep-sheeted gravitational slope deformation is progressed. This deformation should be carefully monitored using InSAR technique in the future. This study was supported by KAKEN 18KK0027, and data used in this study were provided by JAXA in the framework of JAXA’s Landslide Disaster Working Group and PIXEL (PALSAR Interferometry Consortium to Study our Evolving Land surface) under a cooperative research contract with ERI, Univ. of Tokyo.

References, Chigira et al. (2019): Geophysical Research Abstract 21, EGU 2019-2738; Ozawa et al. (2016): https://doi.org/10.1186/s40623-016-0563-5; Morishita et al. (2020): https://doi.org/10.3390/rs12030424; Sato et al. (2020): JpGU 2020, H-GM02-03.