Gorkha earthquake

Gorkha earthquake
Hilmi Hacaloğlu · Public domain · source
Name	Gorkha earthquake
Date	2015-04-25
Time	06:11:26 UTC
Magnitude	7.8 M_w
Depth	8.2 km
Epicenter	Gorkha District, Nepal
Affected	Nepal; India; China (Tibet); Bangladesh
Casualties	~8,900 dead; ~22,000 injured

Gorkha earthquake The Gorkha earthquake struck on 25 April 2015 with a moment magnitude of about 7.8 and caused extensive damage across Nepal and neighboring regions. The event, centered near the town of Lamjung in the Gorkha District, devastated parts of the Kathmandu Valley, affected Mount Everest expeditions, and triggered an international humanitarian response involving multiple states and organisations. Scientific analysis linked the rupture to the collision between the Indian Plate and the Eurasian Plate, producing widespread ground shaking across South Asia.

Background and tectonic setting

The seismic hazard in central Himalaya reflects long-term convergence along the Main Himalayan Thrust, where the Indian Plate subducts beneath the Eurasian Plate. Historical earthquakes such as the 1934 Bihar earthquake and the 1950 Assam–Tibet earthquake illustrate the region's potential for large megathrust and crustal ruptures. Nepal's topography, including the Kathmandu Valley basin and ranges like the Mahabharat Range and Himalayas, concentrates seismic energy and amplifies shaking, as studied by institutions including the Nepal Geological Survey, the United States Geological Survey, and academic centres at Tribhuvan University, University of Cambridge, and Massachusetts Institute of Technology.

Earthquake event

The mainshock ruptured a patch of the shallow portion of the Main Himalayan Thrust near the Gorkha District, producing strong-motion records analysed by the Global Seismographic Network and regional arrays operated by the India Meteorological Department. Focal mechanism solutions from the Harvard CMT project indicated thrust faulting consistent with strain accumulation since previous ruptures. The event generated surface displacement observed by Interferometric Synthetic Aperture Radar studies using satellites such as Sentinel-1, Landsat, and RADARSAT, and was modelled in seismic hazard assessments by teams from King's College London and the National Institute of Standards and Technology.

Impact and casualties

Buildings across the Kathmandu Valley—including heritage sites like Kathmandu Durbar Square, Patan Durbar Square, and Bhaktapur Durbar Square—suffered catastrophic damage, collapsing palaces, temples, and medieval structures. The death toll included residents of urban centres and rural communities in districts such as Gorkha District, Sindhupalchok District, and Nuwakot District, with survivors sheltered by local organisations including the Nepal Red Cross Society and international NGOs such as Save the Children and the International Federation of Red Cross and Red Crescent Societies. The earthquake triggered avalanches on Mount Everest and Annapurna, affecting expeditions organised by companies like Adventure Consultants and medical evacuations coordinated with foreign military assets from India, China, and the United Kingdom.

Response and recovery

Immediate rescue and relief efforts were mounted by the Nepal Army, the Armed Police Force, Nepal, and civil agencies coordinated through the Ministry of Home Affairs (Nepal), while international assistance arrived from countries including India, China, United States, United Kingdom, and organisations such as the United Nations Office for the Coordination of Humanitarian Affairs and the World Bank. Humanitarian logistics used airlift capacity from the Indian Air Force, the Royal Air Force, and cargo operations with support from USAID', and temporary shelters were managed by municipal authorities in Kathmandu Metropolitan City and rural local governments. Reconstruction initiatives involved heritage restoration partners like UNESCO, engineering assessments by the Asian Development Bank, and policy dialogues with donors at conferences chaired by the International Monetary Fund.

Aftershocks and related seismicity

Aftershocks included numerous events above magnitude 5, with seismicity recorded by networks operated by NEA (Nepal Electricity Authority) instrumentation and international arrays. Notable aftershocks changed stress fields along adjacent segments of the Main Himalayan Thrust and prompted studies by researchers at Imperial College London, the Seismological Society of America, and the European-Mediterranean Seismological Centre on cascading hazard potential. Geodetic monitoring of postseismic deformation utilised stations affiliated with the International GNSS Service and long-term implications for regional seismic hazard were integrated into frameworks by the Global Facility for Disaster Reduction and Recovery.

Category:Earthquakes in Nepal Category:2015 earthquakes Category:2015 in Nepal