Geotechnical assessment of the 2023 Jajarkot Nepal Earthquake using field observations and remote sensing

Abstract

On November 3, 2023, at 23:47 local time, a M_W 5.7 earthquake struck Barekot in northwest Nepal at a depth of approximately 12 km. Although the region has been predicted to experience a major earthquake, this moderate-sized earthquake was the most severe seismic event in 518 years. Despite its relatively low magnitude, the earthquake caused significant damage, resulting in 154 deaths and the collapse of over 26,557 houses. This underscores the critical need for post-earthquake reconnaissance to identify vulnerabilities and improve mitigation strategies before more severe events occur. Recognizing this importance, a detailed reconnaissance was conducted from November 6 to 9, 2023, focusing on the geotechnical impact of the earthquake. Based on the field observations, this paper discusses several geotechnical issues triggered by earthquakes in the region, including shallow landslides, rockfalls, and structure damage to flexible pavement and retaining walls. The study also explores the potential triggering mechanisms for the rock fall and discusses possible remedial techniques. Additionally, the influence of the local site effect on the extent of damage was examined. Remote sensing techniques were employed to detect post-earthquake ground patterns and land use changes using Sentinel-1 and Sentinel-2 images, respectively. The Sentinel-1 images were analyzed using the persistent scattering interferometric synthetic aperture radar (PS-InSAR)-based method, and the Sentinel-2 images were analyzed via the Google Earth Engine (GEE). By assessing these geotechnical impacts, this study aims to enhance earthquake preparedness in the future and provide valuable insights for engineers and policymakers to reduce risks and improve disaster resilience.