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Why do landslides and debris avalanches occur frequently in the Nilgiris?
It is a tectonically active region.
The slopes are steep.
Nilgiris are mostly composed of sedimentary and semi consolidated deposits.
Mechanical weathering of rocks is high.
Select the correct answer using code given below.
- a)1 and 2 only
- b)2 and 4 only
- c)3 only
- d)1, 3 and 4 only
Correct answer is option 'B'. Can you explain this answer?
Most Upvoted Answer
Why do landslides and debris avalanches occur frequently in the Nilgi...
- In our country, debris avalanches and landslides occur very frequently in the Himalayas. There are many reasons for this.
- One, the Himalayas are tectonically active.
- They are mostly made up of sedimentary rocks and unconsolidated and semi-consolidated deposits.
- The slopes are very steep.
- Many slopes are steeper with almost vertical cliffs and escarpments in the Western Ghats and Nilgiris.
- Mechanical weathering due to temperature changes and ranges is pronounced.
- They receive heavy amounts of rainfall over short periods.
Hence option (b) is the correct answer.
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Community Answer
Why do landslides and debris avalanches occur frequently in the Nilgi...
Landslides and debris avalanches occur frequently in the Nilgiris due to a combination of factors. The correct options are 2 and 4, which are "The slopes are steep" and "Mechanical weathering of rocks is high". Let's explore these factors in detail:
1. Steep Slopes:
The Nilgiris region is characterized by rugged and hilly terrain with steep slopes. Steep slopes are more prone to landslides as they have a higher gravitational force acting on the soil and rocks. This makes the stability of the slopes weaker, especially during heavy rainfall or seismic activity. The force of gravity, combined with the weight of the overlying material, can overcome the frictional forces holding the slope in place, leading to mass movement.
2. High Mechanical Weathering:
Mechanical weathering refers to the physical breakdown of rocks into smaller fragments without any chemical changes. In the Nilgiris, mechanical weathering processes such as freeze-thaw action, abrasion, and exfoliation occur at a significant rate. These processes weaken the rocks and make them more susceptible to erosion and landslides. The disintegration of rocks into smaller particles increases the chances of landslides as it reduces the cohesion and stability of the slope.
3. Sedimentary and Semi-consolidated Deposits:
The Nilgiris are mostly composed of sedimentary and semi-consolidated deposits. Sedimentary rocks are formed by the accumulation of sediments over time, such as sand, silt, and clay. These rocks are generally less resistant to weathering and erosion compared to igneous or metamorphic rocks. The presence of unconsolidated or loosely packed sediments in the Nilgiris makes the slopes more prone to landslides and debris avalanches.
Therefore, the correct answer is option B, which includes factors 2 and 4. The tectonic activity in the region (option 1) is not a major factor contributing to landslides in the Nilgiris, as the region is not recognized as highly tectonically active. Option 3, which suggests that the Nilgiris are mostly composed of sedimentary and semi-consolidated deposits, is incorrect as it is a valid factor contributing to landslides in the region.
1. Steep Slopes:
The Nilgiris region is characterized by rugged and hilly terrain with steep slopes. Steep slopes are more prone to landslides as they have a higher gravitational force acting on the soil and rocks. This makes the stability of the slopes weaker, especially during heavy rainfall or seismic activity. The force of gravity, combined with the weight of the overlying material, can overcome the frictional forces holding the slope in place, leading to mass movement.
2. High Mechanical Weathering:
Mechanical weathering refers to the physical breakdown of rocks into smaller fragments without any chemical changes. In the Nilgiris, mechanical weathering processes such as freeze-thaw action, abrasion, and exfoliation occur at a significant rate. These processes weaken the rocks and make them more susceptible to erosion and landslides. The disintegration of rocks into smaller particles increases the chances of landslides as it reduces the cohesion and stability of the slope.
3. Sedimentary and Semi-consolidated Deposits:
The Nilgiris are mostly composed of sedimentary and semi-consolidated deposits. Sedimentary rocks are formed by the accumulation of sediments over time, such as sand, silt, and clay. These rocks are generally less resistant to weathering and erosion compared to igneous or metamorphic rocks. The presence of unconsolidated or loosely packed sediments in the Nilgiris makes the slopes more prone to landslides and debris avalanches.
Therefore, the correct answer is option B, which includes factors 2 and 4. The tectonic activity in the region (option 1) is not a major factor contributing to landslides in the Nilgiris, as the region is not recognized as highly tectonically active. Option 3, which suggests that the Nilgiris are mostly composed of sedimentary and semi-consolidated deposits, is incorrect as it is a valid factor contributing to landslides in the region.
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Why do landslides and debris avalanches occur frequently in the Nilgiris? It is a tectonically active region. The slopes are steep. Nilgiris are mostly composed of sedimentary and semi consolidated deposits. Mechanical weathering of rocks is high. Select the correct answer using code given below.a)1 and 2 onlyb)2 and 4 onlyc)3 onlyd)1, 3 and 4 onlyCorrect answer is option 'B'. Can you explain this answer?
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Why do landslides and debris avalanches occur frequently in the Nilgiris? It is a tectonically active region. The slopes are steep. Nilgiris are mostly composed of sedimentary and semi consolidated deposits. Mechanical weathering of rocks is high. Select the correct answer using code given below.a)1 and 2 onlyb)2 and 4 onlyc)3 onlyd)1, 3 and 4 onlyCorrect answer is option 'B'. Can you explain this answer? for UPSC 2025 is part of UPSC preparation. The Question and answers have been prepared according to the UPSC exam syllabus. Information about Why do landslides and debris avalanches occur frequently in the Nilgiris? It is a tectonically active region. The slopes are steep. Nilgiris are mostly composed of sedimentary and semi consolidated deposits. Mechanical weathering of rocks is high. Select the correct answer using code given below.a)1 and 2 onlyb)2 and 4 onlyc)3 onlyd)1, 3 and 4 onlyCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for UPSC 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Why do landslides and debris avalanches occur frequently in the Nilgiris? It is a tectonically active region. The slopes are steep. Nilgiris are mostly composed of sedimentary and semi consolidated deposits. Mechanical weathering of rocks is high. Select the correct answer using code given below.a)1 and 2 onlyb)2 and 4 onlyc)3 onlyd)1, 3 and 4 onlyCorrect answer is option 'B'. Can you explain this answer?.
Why do landslides and debris avalanches occur frequently in the Nilgiris? It is a tectonically active region. The slopes are steep. Nilgiris are mostly composed of sedimentary and semi consolidated deposits. Mechanical weathering of rocks is high. Select the correct answer using code given below.a)1 and 2 onlyb)2 and 4 onlyc)3 onlyd)1, 3 and 4 onlyCorrect answer is option 'B'. Can you explain this answer? for UPSC 2025 is part of UPSC preparation. The Question and answers have been prepared according to the UPSC exam syllabus. Information about Why do landslides and debris avalanches occur frequently in the Nilgiris? It is a tectonically active region. The slopes are steep. Nilgiris are mostly composed of sedimentary and semi consolidated deposits. Mechanical weathering of rocks is high. Select the correct answer using code given below.a)1 and 2 onlyb)2 and 4 onlyc)3 onlyd)1, 3 and 4 onlyCorrect answer is option 'B'. Can you explain this answer? covers all topics & solutions for UPSC 2025 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Why do landslides and debris avalanches occur frequently in the Nilgiris? It is a tectonically active region. The slopes are steep. Nilgiris are mostly composed of sedimentary and semi consolidated deposits. Mechanical weathering of rocks is high. Select the correct answer using code given below.a)1 and 2 onlyb)2 and 4 onlyc)3 onlyd)1, 3 and 4 onlyCorrect answer is option 'B'. Can you explain this answer?.
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