---
title: "Nepal as seismically active zone"
subject: "Engineering Geology II"
chapter: 5
key: "semester_4/engineering_geology_ii:nepal-seismically-active"
source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/nepal-seismically-active
site: BCT Engineering
---

# Nepal as seismically active zone

Engineering Geology II · Chapter 5: Geological Hazards

- Asked in: 2079 Chaitra, 2 marks; 2078 Poush, 2 marks (asked 2 times)
- Video: [Introduction to Nepal and the Earthquake by S. Shrestha](https://www.youtube.com/watch?v=_XZNIieWSvU) — Earthquake Engineering Research Institute (EERI)
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/nepal-seismically-active
- Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-5

## Question

Justify the statement "Nepal is considered as a 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.

## Answer

Nepal lies in the central Himalayan seismic belt, one of the most seismically active regions in the world, for the following reasons.

1. **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.
2. **Active thrusts and faults:** the MFT, MBT, MCT and other active faults cross Nepal from east to west.
3. **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.
4. **Seismic gap:** western Nepal has not had a great earthquake for a long time, so strain is stored there.
5. **Frequent small earthquakes** are recorded daily by the National Seismological Centre.
6. **Hazard zoning:** the Nepal National Building Code (NBC 105:2020) treats the whole country as seismically hazardous, with seismic zoning factors $Z$ from 0.25 to 0.40 (0.35 for Kathmandu).
7. **Geological conditions:** soft sediments in the Kathmandu basin amplify shaking.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Why is Nepal seismically active?
   A. Because of volcanoes
   B. Due to sea waves
   C. Because of desert climate
   D. Indian plate underthrusts Eurasian plate, storing strain on the Main Himalayan Thrust
   Answer: D. Collision at 4-5 cm per year causes strain. (Key point: Plate collision)

2. What is the significance of the western Nepal seismic gap?
   A. No great earthquake for a long time, so strain is stored
   B. It is totally aseismic
   C. It had the 2015 earthquake
   D. It has no faults
   Answer: A. Stored strain implies future large earthquake. (Key point: Seismic gap)

3. What does NBC 105 say about the country?
   A. Only Kathmandu is zoned
   B. Whole country in a high seismic zone
   C. Seismic hazard is negligible
   D. Only Terai is zoned
   Answer: B. Z is about 0.35-0.4 g for most of it. (Key point: Building code)

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