--- title: "Varnes classification of landslides" subject: "Engineering Geology II" chapter: 5 key: "semester_4/engineering_geology_ii:varnes-classification" source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/varnes-classification site: BCT Engineering --- # Varnes classification of landslides Engineering Geology II · Chapter 5: Geological Hazards - Asked in: 2081 Chaitra, 2 marks; 2079 Asoj, 3 marks; 2079 Jestha, 3 marks; 2078 Chaitra, 3 marks; 2077 Chaitra, 4 marks; 2076 Baisakh, 4 marks; 2074 Bhadra, 3 marks; 2073 Bhadra, 3 marks; 2072 Asoj, 3 marks; 2071 Magh, 3 marks; 2070 Bhadra, 4 marks; 2069 Poush, 5 marks; 2068 Magh, 3 marks; 2078 Poush (asked 14 times) - Video: [Why Slopes Fail: The Varnes Rockslide Classification System Explained](https://www.youtube.com/watch?v=3wiBE5rV6pM) — Soil Mechanics and Engineering Geology - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/varnes-classification - Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-5 ## Question Classify landslides (mass movements) according to Varnes (1978). List the types of movement. ## Short answer Varnes (1978) classifies mass movements by movement type (fall, topple, slide, spread, flow, complex) and material (rock, debris, earth). Slides include rotational slump and translational planar slides. Fall example: rock fall; flow example: debris flow. ## Answer **Mass movement** is the downslope movement of rock, debris or soil under gravity. **Varnes (1978)** classified landslides by the **type of movement** and the **type of material** (rock, debris, earth/soil). #### Types of movement 1. **Fall:** detachment and free fall, bouncing or rolling of material from a steep slope; rock fall, debris fall. 2. **Topple:** forward rotation of a rock mass about a point below its centre of gravity; common in columnar jointed rock. 3. **Slide:** movement of a mass along a surface of rupture. - *Rotational slide (slump):* curved slip surface, typically in homogeneous soil. - *Translational (planar) slide:* flat surface, along bedding, joints or foliation. Includes the wedge slide. 4. **Spread (lateral spreading):** lateral extension of a mass with shear or tension fractures; on gentle slopes. 5. **Flow:** the mass moves like a viscous fluid; debris flow, mud flow, earth flow, rock avalanche. 6. **Complex:** a combination of two or more types, e.g. slide-flow. #### Classification table | Movement | Rock | Debris (coarse) | Earth (fine) | |---|---|---|---| | Fall | Rock fall | Debris fall | Earth fall | | Topple | Rock topple | Debris topple | Earth topple | | Rotational slide | Rock slump | Debris slump | Earth slump | | Translational slide | Rock block/rock slide | Debris slide | Earth slide | | Lateral spread | Rock spread | Debris spread | Earth spread | | Flow | Rock avalanche | Debris flow | Earth/mud flow | | Complex | Combination of two or more of the above | Rate of movement: Varnes (1978) ranged it from extremely slow (below 0.06 m/year) to extremely rapid (above 3 m/s); the later revised scale (Cruden and Varnes, 1996) uses below 16 mm/year to above 5 m/s. Water content and speed distinguish slides from flows. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. On what two criteria did Varnes (1978) classify landslides? A. Colour and grain size B. Cost and area C. Type of movement and type of material D. Age and size of the slide Answer: C. Varnes used movement type (fall, topple, slide, spread, flow, complex) and material (rock, debris, earth). (Key point: Basis of Varnes) 2. What is a topple? A. Free fall of material from a steep slope B. Movement along a curved slip surface C. Flow as a viscous fluid D. Forward rotation of a rock mass about a point below its centre of gravity Answer: D. A topple is forward rotation about a pivot below the centre of gravity, typical in columnar jointed rock. (Key point: Topple) 3. Which description fits a rotational slide (slump)? A. Curved slip surface in homogeneous soil B. Flat slip surface along bedding C. Lateral extension on gentle slope D. Mud and water flowing in a channel Answer: A. Rotational slides have curved surfaces; translational slides are planar along bedding or joints. (Key point: Rotational slide) 4. What is a complex landslide? A. A slow creep over centuries B. Combination of two or more types of movement C. A slide in rock only D. A fall of a single boulder Answer: B. Complex movement combines types, e.g. slide-flow. 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