Seismotectonic and Structural Damage Insights from the 2023 Jajarkot Earthquake (ML 6.4), Nepal: Integrating Field Observations with Numerical Simulations

The 2023 Jajarkot earthquake (Mₗ 6.4) struck western Nepal on November 3, causing significant damage to life and infrastructure. This study examines the seismotectonic context, structural vulnerabilities, and post-disaster recovery efforts. Field investigations revealed that unreinforced masonry (URM) buildings suffered extensive collapses due to poor seismic resilience, while reinforced concrete (RC) structures performed better. Key failure mechanisms included out-of-plane wall collapses, inadequate wall connections, and lack of seismic bands. Numerical modeling of a typical stone masonry building validated observed damage patterns, showing failure at 0.7g PGA under EW-direction loading. The earthquake also triggered landslides and road damage, highlighting infrastructure vulnerabilities. Reconstruction efforts faced delays due to logistical challenges, emphasizing the need for improved building practices and policy interventions. Lessons from the event underscore the importance of retrofitting older structures, adopting earthquake-resistant designs, and avoiding high-risk construction zones to mitigate future seismic risks.