Landslides: Types and Causes

Summary

This educational video delves into the hazards of landslides, a recurring phenomenon exacerbated by factors like topography, rainfall, and human activities. It highlights the significant impact on agriculture, infrastructure, and human life, with an annual cost of nearly 2 billion rupees. The script explains the different types of landslides, including falls, topples, slides, and spreads, and discusses the causes, such as slope failure, deforestation, and unscientific development, emphasizing the critical role of human interference in destabilizing slopes.

Takeaways

• 🏔 Landslides are a serious geological hazard, particularly in areas with rugged topography and heavy rainfall.
• 🌧 Landslides are a chronic problem in hilly regions due to factors like development activities and exploitation of natural resources.
• 📈 The monsoon season is a peak time for landslides, causing disruptions in communication, property loss, and sometimes loss of life.
• 🗺 The landslide hazard map of India shows high risk in the Himalayan terrain and northeastern hill ranges, with moderate risk in the western ghats.
• 💔 Landslides have a significant impact on agriculture, forests, infrastructure, and can lead to substantial monetary losses for the nation.
• 🚨 Early warning signs of landslides include tilted structures, cracks in foundations, and changes in water flow or falling debris.
• 📚 Landslides involve the downward and outward movement of soil or rock mass due to gravity and can be categorized into different types like falls, topples, slides, and spreads.
• 🔍 Key terms in landslide studies include crown, flanks, head, foot, main scarp, and surface of rupture, which help in understanding the mechanics of landslides.
• 📉 The types of landslides range from rock falls and debris slides to complex landslides that involve a combination of different movements.
• 🌳 Causes of landslides include slope failure, deforestation, hydrostatic pressure, earthquakes, intense rainfall, and human activities such as construction and land use changes.
• ⚠️ Human interference, such as improper construction practices and deforestation, significantly contributes to the instability of slopes and the occurrence of landslides.

Q & A

What is a landslide?

A landslide is a serious geological hazard involving the downward and outward movement of soil or rock mass under the influence of gravity, often triggered by factors such as heavy rainfall, slope failure, or human activities.

Why are landslides particularly common during the monsoon season?

Landslides are particularly common during the monsoon season due to heavy and prolonged rainfall, which increases the water content in the soil, reducing its stability and leading to slope failure.

What are the areas in India most prone to landslides according to the landslide hazard map?

According to the landslide hazard map, the Himalayan terrain, northeastern hill ranges, and western ghats are the areas most prone to landslides in India.

What are the socioeconomic impacts of landslides?

Landslides can cause substantial damage to agriculture, forests, roads, and telecommunication infrastructure. They can also result in injury, loss of life, and property damage, leading to significant monetary losses for the nation.

What are some early warning signs of a potential landslide?

Early warning signs of a potential landslide include tilted telephone poles or trees, cracks in foundations or roads, and sudden changes in the flow of water or falling of stones from hill slopes.

What types of landslides are mentioned in the script?

The script mentions several types of landslides, including rock fall, debris fall, soil fall, rock topple, debris topple, soil topple, rotational slides, translational slides, and complex landslides.

How do rotational slides differ from translational slides?

Rotational slides involve movement on a circular or near-circular surface of failure and are characterized by a scarp at the head. Translational slides, on the other hand, are non-rotational and involve mass movement on more or less planar surfaces.

What is the role of human activities in causing landslides?

Human activities such as deforestation, unscientific construction practices, and developmental projects like road building can destabilize slopes and contribute to landslides by altering the natural landscape and increasing the load on hill slopes.

How do earthquakes contribute to landslides?

Earthquakes can contribute to landslides by reducing the shearing resistance along fracture zones or joint planes, making loose and unconsolidated sediments on steep slopes more vulnerable to movement.

What is the significance of the surface of rupture in understanding landslides?

The surface of rupture is significant in understanding landslides as it represents the plane along which the soil or rock mass moves. Identifying this surface helps in assessing the type and potential movement of a landslide.