- Asked 2/26
- 2079 Chaitra · 2 marks
- 2078 Poush · 2 marks
Nepal as seismically active zone
Short answer
Nepal lies where India underthrusts Eurasia at ~4–5 cm/yr, straining the Main Himalayan Thrust. Active faults, historical M8+ earthquakes, a western seismic gap, and building code factors up to 0.40 prove it is seismically active.
Justify the statement "Nepal is considered as a seismically active zone".
Nepal lies in the central Himalayan seismic belt, one of the most seismically active regions in the world, for the following reasons.
- Plate tectonics: the Indian plate collides with and underthrusts the Eurasian plate at about 4-5 cm per year (around 2 cm per year is taken up across the Himalaya), so large strain accumulates on the Main Himalayan Thrust and is released as earthquakes.
- Active thrusts and faults: the MFT, MBT, MCT and other active faults cross Nepal from east to west.
- Historical earthquakes: 1255, 1344, 1408, 1833, 1934 Bihar-Nepal (M 8.1), 1988 Udayapur (M 6.8), and the 2015 Gorkha (M 7.8) and Dolakha (M 7.3) earthquakes, which killed thousands.
- Seismic gap: western Nepal has not had a great earthquake for a long time, so strain is stored there.
- Frequent small earthquakes are recorded daily by the National Seismological Centre.
- Hazard zoning: the Nepal National Building Code (NBC 105:2020) treats the whole country as seismically hazardous, with seismic zoning factors from 0.25 to 0.40 (0.35 for Kathmandu).
- Geological conditions: soft sediments in the Kathmandu basin amplify shaking.
✓ Answer checked by Claude Opus 5.5 (high effort)
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