---
title: "Discontinuities and engineering problems in Nepal Himalaya"
subject: "Engineering Geology I"
chapter: 7
key: "semester_3/engineering_geology_i:discontinuities-and-engineering-problems-in"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/discontinuities-and-engineering-problems-in
site: BCT Engineering
---

# Discontinuities and engineering problems in Nepal Himalaya

Engineering Geology I · Chapter 7: Geology of Nepal

- Asked in: 2081 Kartik (new course), 2+2 marks
- Video: [Road or Tunnel How Engineers Choose Routes Through Nepal’s Himalayas](https://www.youtube.com/watch?v=0Yx_Vo7O7vY) — DT Civil Core
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/discontinuities-and-engineering-problems-in
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-7

## Question

Describe the major discontinuity systems and their engineering significance along with the different engineering geological problems in the different tectonic subdivisions of the Nepal Himalaya.

## Short answer

The major discontinuity systems are MFT/HFT, MBT, MCT, and STDS, all major thrust/faults with crushed, sheared weak ground, seismically active, causing earthquakes, landslides, and water inflow. Engineering problems include floods in Terai, slides in Siwalik, shear zones in Lesser Himalaya, rockfall/avalanches in Higher Himalaya, and karst in Tethys.

## Answer

#### Major discontinuity systems
| Thrust | Between | Tentative location | Age of last movement |
|---|---|---|---|
| MFT / HFT | Terai and Siwalik | Along the southern foot of the Churiya hills | Active (Holocene) |
| MBT | Siwalik and Lesser Himalaya | Along the northern edge of the Siwaliks / foot of the Mahabharat range | Late Pleistocene, reactivated |
| MCT | Lesser and Higher Himalaya | Along the foot of the Higher Himalaya, mostly north of Kathmandu | Miocene, partly active |
| STDS | Higher Himalaya and Tethys | Along the northern slopes of the Great Himalaya | Normal fault, Miocene |

#### Engineering significance
- All are major thrusts or faults: crushed, sheared and weak ground, tunnelling and slope problems.
- They are seismically active, so earthquakes, surface rupture and landslides are linked with them.
- Springs, seepage and groundwater concentrate along them.
- Structures (dams, powerhouses) should avoid crossing them.

#### Problems in the tectonic subdivisions
| Zone | Main engineering geological problems |
|---|---|
| Terai | Floods, river shifting and bank cutting, high water table, soft soils with low bearing capacity, liquefaction, arsenic in groundwater, no rock for aggregate |
| Siwalik | Weak, poorly consolidated rocks, landslides and debris flows, gully erosion, swelling mudstone, slaking, flash floods, steep slopes |
| Lesser Himalaya | Landslides in weathered phyllite and schist, shear zones along thrusts, karst and cavities in limestone, tunnel squeezing, seepage |
| Higher Himalaya | Very high relief and steep valleys, rockfall, avalanches, glacial lake outburst floods, moraine slides, difficult access, cold and frost |
| Tethys Himalaya | Karst in limestone, frost and permafrost, rockfall, cold, remoteness |
| Boundary thrusts (MFT, MBT, MCT) | Crushed zone, weak ground, earthquakes, landslides, water inflow |

## Check yourself

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

1. Why should dams and powerhouses avoid crossing major thrusts?
   A. They have the strongest rock
   B. They contain no water
   C. They are inactive
   D. They have crushed, sheared, weak ground and are seismically active
   Answer: D. Springs and seepage also concentrate along them. (Key point: Significance)

2. MBT is located:
   A. Along the northern edge of the Siwaliks / foot of the Mahabharat range
   B. At the southern foot of the Churiya
   C. On the northern slopes of the Great Himalaya
   D. In the Terai plain
   Answer: A. Its last movement is Late Pleistocene, reactivated. (Key point: MBT)

3. Higher Himalaya problems include:
   A. Arsenic in groundwater
   B. Very high relief, rockfall, avalanches and GLOF
   C. Liquefaction
   D. Swelling mudstone
   Answer: B. Terai has floods and arsenic. (Key point: Higher Himalaya problems)

4. Problems at boundary thrusts include:
   A. Only permafrost
   B. Only floods
   C. Crushed zone, weak ground, earthquakes, landslides and water inflow
   D. No problems
   Answer: C. These are the problems of MFT, MBT and MCT. (Key point: Boundary thrusts)

## Related in Engineering Geology I

- [Engineering geological problems in tectonic divisions](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aengineering-geological-problems-in-tectonic) — Engineering Geology I, chapter 7, asked 2×
- [Tectonic zones and major discontinuities](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atectonic-zones-and-major-discontinuities) — Engineering Geology I, chapter 7, asked 2×
- [Tectonic divisions of the Nepal Himalaya](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atectonic-divisions-of-the-nepal) — Engineering Geology I, chapter 7, asked 4×
- [Discontinuities; Siwalik and Higher Himalaya lithology](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Adiscontinuities-siwalik-and-higher-himalaya) — Engineering Geology I, chapter 7
- [Tectonic division and Lesser Himalaya geology](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atectonic-division-and-lesser-himalaya) — Engineering Geology I, chapter 7
- [Tectonic divisions with sketch and problems](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Atectonic-divisions-with-sketch-and) — Engineering Geology I, chapter 7, asked 4×

## Related in other subjects

- [Major discontinuity systems of Nepal Himalaya](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Anepal-discontinuity-systems) — Engineering Geology II, chapter 2, asked 12×
- [Mitigation of geological problems in Himalaya](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Ahimalaya-problems-mitigation) — Engineering Geology II, chapter 2
- [Engineering geological problems of Siwalik zone](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Asiwalik-problems) — Engineering Geology II, chapter 2, asked 4×
- [Problems of Lesser Himalaya with mitigation](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Alesser-himalaya-problems) — Engineering Geology II, chapter 2, asked 5×