History of Earth: Landslides – Definition, Causes and Types

In this article, we’ll learn about Landslides and its definition, causes and types. Let’s begin

Introduction of Landslides

Have you ever heard on the news that some roads in the mountains were closed due to landslides? In this session, we will discuss the mass movement of landmass, the meaning of landslides, and the causes of landslides.

Let’s discuss this in detail.

Landslides

A landslide is a rapid and sudden movement of a large amount of material downslope.

Landslides can carry away plants and animals or bury their habitats.

The main cause of a landslide is the effect of gravity overcoming the stability of a slope through friction.

Landslides cause rapid changes to the earth’s surface because the area that slopes rapidly becomes flat, altering the earth’s surface.

The Earth’s surface can crack and shift during an earthquake above the point where the crust moves. The land can be pushed up or dragged along this area.

Landslides change the slope of a steep hill and the land at the foot of a hill as the landslides down and off the slope.

A slump, shown in the figure, is the most common kind of landslide.

Slumping occurs when a block of material moves downslope over a curved surface.

Heavy rains, deforestation, construction on unstable slopes, and earthquakes increase the chance that a landslide will happen.

Causes of Landslides

Three major causes of landslides are geology, morphology, and human activity.

Geology

It is the characteristics of the material itself. The earth or rock might be cracked or weak, or different layers might have different strengths and stiffness.

Morphology

It denotes the structure of the land. For example, slopes that lose their vegetation to forest fire or drought are more prone to landslides. Vegetation holds soil in place, and without root systems, the land is more likely to slide away.

Human Activity

Human activity, such as agriculture and the construction of roads, railways, buildings, etc., can increase the risk of landslides. Activities such as deforestation, irrigation, excavation, and water leakage can help destabilize or weaken a slope.

Types of Landslides

The different types of landslides are categorized by the types of material, the slope, and the direction of movement.

Here are a few:

Falls Landslides

Falls are movements of often larger rocks and boulders through the air rather than along the ground in free-fall, bouncing, and rolling.

Falls are often the result of material becoming detached from cliffs and other overhanging formations.

Topple Landslides

These occur because of some fractures between the rocks and the tilt of the rocks because of gravity without collapsing.

Here, we see the forward rotational movement of the material.

Slides

Slides are movements of material, either in large or fine pieces, down a slope where there is a distinct separation between the moving material and the underlying foundation.

This type of movement is the most technical definition of a landslide.

There are two types of slides which include rotational and translational.

Rotational slide – In a rotational slide, the material moves along a pivot point, a center of gravity that is lower in elevation than the mass of the material. This type of slide leaves a concave shape in its path.

A translational slide is one in which the mass moves along a parallel line with the underlying base.

Spread

This happens on flat terrain and gentle slopes and can occur because of softer material.

Flow

This comes in many types: debris flow, debris avalanche, mudflow, creep, and earth flow.

Debris flows: It involves the rapid downhill movement of loose earth material, usually with water.

Debris Avalanche – It is similar to debris flow but has a faster flow.

Flow

Earth flow – In an earthflow, the earth material is finer and washed away, leaving a depression bowl at the head.

Mudflow – Mudslides are made of fine silt, sand, and clay material saturated with water and flowing very rapidly.

Creeps – These are slower and can be evident when electric poles and roads bend slightly.

Effects of Landslides

It can disturb the social and economic environment with a number of other damages, which are mentioned below.

Short-term Impacts

• Loss of life and property.
• Roadblocks
• Damage to the natural beauty of the area.
• The blocking of the channel because of the falling of rocks.
• Destruction of railway lines
• Flooding

Long-term Impacts

• Landscape changes can be permanent.
• The loss of cultivation land or fertile land.
• Erosion and soil loss can lead to environmental problems.
• Population shifting and migration.
• Effects on the sources of water.
• Some roads can be damaged or closed permanently.