Which of the following statements regarding landslides is/are correct? 1. They are sudden and sporadic. 2. They result when the slope is gentle. 3. Mining activity is also responsible for landslides. Select the correct answer using the code given below.

1. Mass Wasting: The Broader Context (basic)

To understand the physical landscape of India—from the crumbling slopes of the Himalayas to the stable Deccan Plateau—we must first grasp the concept of **Geomorphic Processes**. These are forces that shape the Earth's surface. We divide them into two main types: **Endogenic** (forces from within the Earth, like volcanoes) and **Exogenic** (forces acting from above the surface, like wind and water) Physical Geography by PMF IAS, Geomorphic Movements, p.82.

Mass Wasting (also known as mass movement) is a vital exogenic process. It is defined as the downslope movement of rock debris, soil, and organic matter primarily under the direct influence of gravity. It is important to distinguish this from erosion: while erosion involves a 'geomorphic agent' (like a river or wind) physically picking up and transporting material, in mass wasting, the material moves simply because gravity pulls it down a slope FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Geomorphic Processes, p.38.

Mass wasting doesn't happen in isolation. It is usually preceded by weathering, which is the mechanical or chemical breaking down of rocks Certificate Physical and Human Geography, GC Leong, Weathering, Mass Movement and Groundwater, p.36. Once the rock is weakened and loose, gravity finds it much easier to pull it down. The speed of this movement varies greatly—it can be a nearly invisible 'creep' occurring over years, or a sudden, violent landslide triggered by heavy rain or an earthquake.

Feature	Mass Wasting	Erosion
Driving Force	Direct Gravity	Kinetic energy of agents (water, wind)
Medium	No transporting medium required	Requires a medium (ice, air, water)
Role of Water	Acts as a lubricant or adds weight	Acts as the primary vehicle for transport

Sources: Physical Geography by PMF IAS, Geomorphic Movements, p.82; FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Geomorphic Processes, p.38; Certificate Physical and Human Geography, GC Leong, Weathering, Mass Movement and Groundwater, p.36

2. Slope Dynamics and Stability (intermediate)

To understand why the earth moves beneath our feet, we must first look at the invisible battle occurring on every hill and mountain: the battle between gravity and friction. This phenomenon is known as Mass Movement. Unlike erosion, where water or wind carries debris away, mass movement is the down-slope movement of rock and soil primarily under the direct pull of gravity. As noted in NCERT Class XI, Geomorphic Processes, p.42, these materials will only yield and move when the disturbing force becomes greater than the internal resistance of the material.

The core physics of slope stability involves two competing forces: Shear Stress and Shear Resistance.

• Shear Stress: This is the component of gravity acting parallel to the slope, trying to pull material downward. The steeper the slope, the higher the shear stress. NCERT Class XI, Geomorphic Processes, p.39.
• Shear Resistance: This is the "internal strength" of the slope, provided by the friction between particles and the cohesion (stickiness) of the soil or rock.

When the stress exceeds the resistance, a landslide or failure occurs. While some slow movements like "lateral spreads" can happen on gentler gradients, true landslides—characterized by rapid, sudden movements—are almost exclusively associated with steep slopes and vertical cliffs. GC Leong, Weathering, Mass Movement and Groundwater, p.40.

Several factors act as "triggers" that tip this balance. Natural triggers include heavy rainfall (which adds weight and lubricates the soil) and tectonic activity like earthquakes. However, human interference is a massive contributor. Activities such as mining or the construction of roads and railways often involve undercutting (removing the base of a slope) or artificial steepening, which dangerously increases the shear stress. Majid Husain, Contemporary Issues, p.4.

Factor	Effect on Stability	Mechanism
Vegetation	Increases Stability	Roots bind the soil and absorb excess water.
Saturation (Rain)	Decreases Stability	Reduces friction and increases the weight of the material.
Slope Angle	Decreases Stability	Steeper angles directly increase gravitational shear stress.

Sources: FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.), Geomorphic Processes, p.39, 42; Certificate Physical and Human Geography, GC Leong (Oxford University press 3rd ed.), Weathering, Mass Movement and Groundwater, p.40; Geography of India, Majid Husain (McGrawHill 9th ed.), Contemporary Issues, p.4

3. Landslide Hazard Zonation in India (exam-level)

To understand Landslide Hazard Zonation in India, we must first look at the first principles: a landslide is the rapid, down-slope movement of rock, soil, or debris under the influence of gravity. While gravity is the driving force, the likelihood of a landslide occurring is determined by the slope gradient (steepness), geological stability (rock type and age), and triggering factors like heavy rainfall or seismic activity GC Leong, Certificate Physical and Human Geography, Chapter 4, p.40. In India, because our geography varies from the young, volatile Himalayas to the ancient, stable Deccan Plateau, the risk is categorized into distinct zones.

The Very High Vulnerability Zone includes areas where all risk factors converge: steep slopes, high rainfall, and frequent ground shaking. This includes the Himalayas, the Andaman and Nicobar Islands, and the Western Ghats/Nilgiris. Interestingly, the North-Eastern regions (excluding the plains) also fall into this high-risk category due to intense monsoonal rain and tectonic instability NCERT Class XI, India Physical Environment, Natural Hazards and Disasters, p.66. In contrast, Moderate to Low Vulnerability Zones include areas like the Trans-Himalayan regions of Ladakh. Even though Ladakh is mountainous, its arid climate (low precipitation) makes it less prone to landslides than the rain-soaked southern slopes of the Himalayas NCERT Class XI, India Physical Environment, Natural Hazards and Disasters, p.67.

Human activities further complicate this zonation. While nature dictates the primary zones, anthropogenic factors create localized hotspots. For instance, in states like Uttarakhand, unplanned urbanization and construction on fragile slopes (like the eastern slopes of Nainital) have increased vulnerability Majid Hussain, Environment and Ecology, Natural Hazards and Disaster Management, p.40-41. Meanwhile, in the mineral-rich belts of Jharkhand, Odisha, and Chhattisgarh, landslides are often triggered by mining activities and land subsidence rather than natural topography NCERT Class XI, India Physical Environment, Natural Hazards and Disasters, p.67.

Vulnerability Zone	Key Regions	Primary Controlling Factors
Very High	Himalayas, Andaman & Nicobar, Western Ghats	Steep slopes, high rainfall, tectonic activity, intense human construction.
High	Most North-Eastern States (except Assam plains)	High rainfall and frequency of triggers similar to Very High zone.
Moderate to Low	Ladakh, Spiti, Aravali, Rain shadow areas of Deccan	Stable relief or very low precipitation levels.
Safe Areas	Rajasthan, Haryana, Indo-Gangetic Plains	Flat terrain and stable geological structures.

Sources: Certificate Physical and Human Geography, Chapter 4: Weathering, Mass Movement and Groundwater, p.40; INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Natural Hazards and Disasters, p.66-67; Environment and Ecology, Majid Hussain (Access publishing 3rd ed.), Natural Hazards and Disaster Management, p.40-41

4. Himalayas vs. Western Ghats Landslides (exam-level)

To understand why landslides behave differently in India's two most prominent highland regions, we must first look at their geological DNA. A landslide is the sudden, rapid downward movement of rock or soil under the influence of gravity, typically occurring on steep slopes Environment and Ecology by Majid Hussain, Natural Hazards and Disaster Management, p.39. While both the Himalayas and the Western Ghats are prone to these disasters, the trigger and frequency differ based on their physical origins.

The Himalayas are young fold mountains formed by the ongoing Continent-Continent (C-C) convergence. Because they are still rising, they are tectonically active and subject to recurrent seismicity. Geologically, they consist largely of sedimentary rocks and unconsolidated deposits, which are physically weaker and more prone to crumbling Physical Geography by PMF IAS, Geomorphic Movements, p.89. In this region, earthquakes are often the primary catalyst that destabilizes these fragile slopes Physical Geography by PMF IAS, Types of Mountains, p.136.

In contrast, the Western Ghats and the Nilgiris are tectonically stable and composed of much older, harder rocks. However, they are not immune to landslides. Their vulnerability stems from their sheer vertical cliffs and escarpments, combined with intense seasonal rainfall during the monsoon Exploring Society: India and Beyond, NCERT Class VII, Climates of India, p.62. While the Himalayas suffer from geological instability, the Western Ghats suffer from topographic steepness and high-intensity weather events.

Feature	The Himalayas	The Western Ghats
Geology	Young, Sedimentary, Unconsolidated	Old, Hard Igneous/Metamorphic rocks
Tectonic Status	Active (High Seismicity)	Relatively Stable
Primary Triggers	Earthquakes, Heavy Rain, Steep Slopes	Heavy Rainfall, Steep Escarpments

Finally, we cannot ignore the anthropogenic (human) factor. In both regions, activities like building infrastructure without following approved methods, cutting down forests, and mining have significantly increased landslide frequency by blocking natural water flows and undercutting stable slopes Exploring Society: India and Beyond, NCERT Class VII, Climates of India, p.62.

Sources: Environment and Ecology by Majid Hussain, Natural Hazards and Disaster Management, p.39; Physical Geography by PMF IAS, Geomorphic Movements, p.89; Physical Geography by PMF IAS, Types of Mountains, p.136; Exploring Society: India and Beyond, NCERT Class VII, Climates of India, p.62

5. Anthropogenic Triggers: Mining and Infrastructure (intermediate)

While nature provides the raw materials for landslides through gravity and rainfall, human activity often acts as the final 'trigger' that causes a slope to fail. In the context of Indian geography, anthropogenic triggers—or human-induced causes—are increasingly responsible for disasters in fragile ecosystems like the Himalayas and the Western Ghats. The primary mechanism involves disturbing the slope stability. Every slope has a natural 'angle of repose,' which is the steepest angle at which soil or rock remains stable. When we engage in road-cutting or rail construction, we often perform what is known as 'toe-cutting'—removing the base support of a mountain to create a flat path. This artificially steepens the slope beyond its limit, making it highly susceptible to sudden collapses, a phenomenon frequently seen along the Konkan Railway and the Srinagar-Jammu National Highway (NH-1A) INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Natural Hazards and Disasters, p.66.

Mining and quarrying represent another massive anthropogenic threat. The continuous extraction of coal, minerals, and building stones involves two dangerous elements: the physical removal of material that provides lateral support and the use of explosives for blasting. These explosions send high-frequency vibrations through the rock layers, creating micro-fractures that weaken the integrity of the entire hill-face. Such activities have been identified as major contributors to landslides throughout the Himalayas, the North-East hill states, and the Nilgiris Environment and Ecology, Majid Hussain, Natural Hazards and Disaster Management, p.40.

Beyond physical excavation, human interference changes how water interacts with the earth. By clearing natural vegetation for housing or agriculture, we remove the 'root anchors' that hold the soil together. More critically, the removal of plant cover allows rainwater to penetrate deep into the soil (regolith) rather than being absorbed by plants. This water eventually reaches the interface between the loose soil and the hard bedrock, acting as a lubricant that allows the entire mass to slide down easily Certificate Physical and Human Geography, GC Leong, Weathering, Mass Movement and Groundwater, p.40. In India, this is a common sight where steep slopes have been converted into tea gardens or residential zones Geography of India, Majid Husain, Contemporary Issues, p.5.

Sources: INDIA PHYSICAL ENVIRONMENT, Geography Class XI (NCERT 2025 ed.), Natural Hazards and Disasters, p.66; Geography of India, Majid Husain, Contemporary Issues, p.5; Environment and Ecology, Majid Hussain, Natural Hazards and Disaster Management, p.40; Certificate Physical and Human Geography, GC Leong, Weathering, Mass Movement and Groundwater, p.40

6. Characteristics of Landslides (exam-level)

A landslide is essentially a form of mass wasting where a cohesive mass of rock, debris, or earth moves down a slope under the direct influence of gravity. Unlike simple erosion, which involves a transport agent like water or wind carrying away individual particles, a landslide involves the movement of a large, unified volume of material. These events are characterized by their sudden and rapid nature, often occurring in a matter of seconds, though some complex slides can slip gradually over longer periods Environment and Ecology, Majid Hussain, p.38.

The topography plays a decisive role in these events. Landslides are almost exclusively associated with steep slopes, such as those found in the Himalayas, the Western Ghats, or coastal cliffs. While some forms of slow mass movement, like soil creep, can occur on moderate gradients, true landslides require the gravitational pull to overcome the internal friction of the slope material. Areas at the top of long ridges or flat plains are generally considered safe, whereas the "toe" (the base) of a steep slope is the most vulnerable zone Environment and Ecology, Majid Hussain, p.39.

While natural factors like heavy monsoon rainfall, earthquakes, and volcanic disturbances are primary triggers, human interference has significantly accelerated these hazards in India. Activities such as undercutting slopes for road or rail construction, large-scale mining vibrations, and the blocking of natural drainage systems through unplanned urbanization create artificial instability. In hilly regions like Himachal Pradesh or Sikkim, the combination of fragile geology and infrastructure development has made landslides a recurring seasonal disaster Exploring Society: India and Beyond, NCERT, p.62.

Feature	Landslide	Soil Creep
Speed	Sudden and Rapid	Extremely slow / Imperceptible
Slope Type	Primarily Steep Slopes	Moderately steep to gentle slopes
Evidence	Visible scars, debris piles	Tilted fence posts or telephone poles

Sources: Environment and Ecology, Majid Hussain, Natural Hazards and Disaster Management, p.38-39; Exploring Society: India and Beyond, NCERT, Climates of India, p.62; Physical Geography, PMF IAS, Geomorphic Movements, p.86

7. Solving the Original PYQ (exam-level)

Now that you have mastered the mechanics of mass wasting and the role of gravity, this question tests your ability to synthesize those building blocks into a practical scenario. As we explored in Certificate Physical and Human Geography (G.C. Leong), landslides are not slow, continuous processes like soil creep; they are sudden and sporadic movements of debris triggered by specific events like heavy rainfall or tectonic activity. This directly confirms Statement 1. Similarly, your understanding of anthropogenic factors allows you to see how mining activity acts as a catalyst by undercutting slopes and creating mechanical vibrations that destabilize the earth, making Statement 3 an easy inclusion.

To arrive at the correct answer, you must apply the physical principle of shear stress. A landslide occurs when the downward force of gravity overcomes the internal resistance of the soil or rock. This mechanical failure typically requires a steep slope to provide the necessary gravitational momentum. Statement 2 is a classic UPSC trap; it uses the word "gentle" to describe a phenomenon that, by definition, requires significant topographic relief. While very slow movements can happen on low gradients, true landslides are synonymous with steep mountainous terrains, as highlighted in Geography of India (Majid Husain).

By identifying that Statement 2 is factually inverted, you can confidently eliminate Options (A), (C), and (D). This leaves you with the correct answer: (B) 1 and 3 only. Remember, the UPSC often tests your conceptual precision by swapping a single word—like "gentle" for "steep"—to see if you can distinguish between general mass movements and the specific high-energy nature of a landslide.