---
title: "Factors of mass movement"
subject: "Engineering Geology II"
chapter: 5
key: "semester_4/engineering_geology_ii:factors-of-movement"
source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/factors-of-movement
site: BCT Engineering
---

# Factors of mass movement

Engineering Geology II · Chapter 5: Geological Hazards

- Asked in: 2081 Chaitra, 2 marks
- Video: [Mass Wasting/Mass Movement](https://www.youtube.com/watch?v=xtYKfmiG66M) — Dr. Kashif Imdad
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/factors-of-movement
- Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-5

## Question

What are the factors of movement (of mass movement)?

## Short answer

Mass movement is driven by increase in shear stress or reduction in shear strength. Key factors are steep slopes, water raising pore pressure and weight, weak and fractured rocks, adverse geological structures, vegetation removal, earthquakes, toe undercutting, loading, weathering, and human activities.

## Answer

The factors of mass movement are those that increase the shear stress or lower the shear strength of the slope.

#### Causes by group
1. **Gravity and slope:** steep slope angle, large relief.
2. **Water:** rainfall, snow melt and groundwater raise pore pressure and weight, and reduce friction and cohesion.
3. **Material:** weak, weathered or clay-rich rocks and soils; loose debris.
4. **Structure:** joints, bedding and foliation dipping out of the slope, faults and shear zones.
5. **Vegetation:** removal of forest lowers root cohesion.
6. **Earthquake and vibration:** shaking, blasting, traffic.
7. **Toe undercutting:** by river erosion or road cuts.
8. **Loading:** buildings, fills, and water in the reservoir.
9. **Weathering:** freeze-thaw, wetting-drying, chemical decay.
10. **Human activities:** mining, irrigation, deforestation.

## Check yourself

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

1. What do all factors of mass movement do?
   A. Increase the friction angle
   B. Reduce pore pressure
   C. Lower the slope angle
   D. Increase shear stress or lower shear strength
   Answer: D. Either effect pushes the slope toward failure. (Key point: Principle)

2. How does water contribute to movement?
   A. Raises pore pressure and weight, reduces friction and cohesion
   B. Increases cohesion between particles
   C. Reduces the weight of the mass
   D. Binds soil with roots
   Answer: A. Rainfall, snow melt and groundwater weaken slopes. (Key point: Water effect)

3. Why does removing vegetation promote movement?
   A. It prevents toe undercutting
   B. It lowers root cohesion
   C. It increases cohesion
   D. It reduces rainfall
   Answer: B. Roots bind soil; removal reduces strength. (Key point: Vegetation)

## Related in Engineering Geology II

- [Mass movement and its mechanism](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Amass-movement-mechanism) — Engineering Geology II, chapter 5, asked 11×
- [Factors and process of groundwater movement](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Agroundwater-movement-factors) — Engineering Geology II, chapter 3, asked 4×

## Related in other subjects

- [Define mass movement and its classification](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Adefine-mass-movement-and-its) — Engineering Geology I, chapter 6, asked 5×
- [All mass movements are landslides](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aall-mass-movements-are-landslides) — Engineering Geology I, chapter 6