Abstract:
Slope instability due to tectonic, hydrological and anthropogenic activities cause severe
landslides in Himalaya. Joshimath, a densely populated Himalayan town witnessed a catastrophic landslide
event during December 2022 and January 2023 causing damages to ∼700 buildings. We use Interferometric
synthetic aperture radar, Global Positioning System and rainfall measurements to probe the kinematics of the
Joshimath landslide. We separate the seasonal and episodic deformation components using singular spectrum
analysis. While the low amplitude annual landslide motions are modulated by seasonal precipitation,
acceleration phases are triggered by extreme rain events. Our analysis revealed episodes of cascading motions
triggered by extreme rain events resulting an overall increase in landslide velocity from − 22 mm/yr during
2004–2010 to − 325 mm/yr during 2022–2023. We estimate the landslide depth (∼30 m) and hydraulic
diffusivity (∼3 × 10− 5 m2
/s) using a 1‐D pore‐water pressure diffusion model. Our study reveals the importance
of systematic monitoring of ground deformation and weather parameters for landslide hazard mitigation.
