Effects of earthquake in Nepal

Nepal lies on the Himalayan collision zone where the Indian plate underthrusts the Eurasian plate at about 40 to 50 mm per year, so earthquakes are frequent and severe (1934 Nepal-Bihar M 8.0 to 8.4, 1988 Udayapur M 6.6, 2015 Gorkha M 7.8). The main effects are:

1. Ground shaking: the main cause of damage. Collapse of unreinforced masonry, mud-mortar and stone houses; about 9,000 deaths and over 500,000 houses destroyed in 2015.
2. Landslides and rockfalls: shaking triggers thousands of slides on steep, fractured Himalayan slopes (Langtang, Sindhupalchok, Gorkha), blocking roads and trails.
3. Liquefaction and ground failure: in loose, saturated sands (Kathmandu valley fill, Terai) the soil loses strength, causing settlement, tilting of buildings and sand boils.
4. Surface rupture and ground cracks: along faults such as the Main Himalayan Thrust and its branches.
5. Damming and floods: landslides block rivers and form temporary lakes, with the danger of outburst floods. Cracks and damage to dams and canals.
6. Snow and ice avalanches: the 2015 shock caused avalanches at Everest Base Camp and Langtang.
7. Damage to infrastructure and heritage: roads, bridges, water supply, hydropower plants, temples and monuments (Dharahara, Durbar Squares).
8. Secondary effects: fires, epidemics, loss of livelihoods, displacement and heavy economic loss (about 7 billion US dollars in 2015).

Reduction: seismic zoning, Nepal Building Code (NBC 105), retrofitting, safe site selection and public awareness.