Performance of Residential Buildings during the M 7.8 Gorkha (Nepal) Earthquake of 25 April 2015

The M 7.8 earthquake of 25 April 2015 was a significant event in the long seismic history of the Eastern Himalayas, which caused more than 8000 casualties; widespread destruction of residential, commercial and cultural heritage structures, surface fissures and landslides in the western and central regions of Nepal. It was followed by a strong aftershock of M 7.3 after 17 days of the main event which caused further damage. These events provided a unique opportunity to study the vulnerability of the built environment and reassess the risk exposure of the region which is undergoing rapid urbanization without adequate preparedness for seismic safety. A field trip was undertaken covering the affected regions of Nepal and adjoining Indian states of Uttar Pradesh and Bihar. This article discusses the general observations in the earthquake affected regions, with special emphasis on the seismic performance of residential structures in the Kathmandu valley region.