What is the Difference Between Landslide and Avalanche

The main difference between landslide and avalanche is that landslides occur on land whereas avalanches occur on snow.

Both landslide and avalanche refer to the movement of a large stationary mass under the force of gravity. These are very dangerous processes that can cause many damages and deaths. 

Key Areas Covered

1. What is a Landslide 
     – Definition, Characteristics, Causes
2. What is an Avalanche
     – Definition, Characteristics, Causes
3. What is the Difference Between Landslide and Avalanche
     – Comparison of Key Differences

Key Terms

Avalanche, Landslide, Disasters

What is a Landslide

Landslides are a form of mass wasting that includes the movement of a large area of land under the force of gravity. This can occur as a soil movement, rockfalls, mudflows, debris flows, etc. A landslide can take place in a variety of environments such as mountains, coastal cliffs, underwater (submarine slides), etc. This type of land movement occurs where there is a steep slope or a gentle slope that cannot hold the land tight to itself. Gravity is the primary force of driving the land from one place to another. Generally, a landslide is triggered by a particular event such as heavy rainfall, earthquakes, building roads by cutting mountains, etc.

There are different types of landslides. The two most common forms of landslide include debris landslide and earthflow. Debris landslide is caused by the saturation of the debris matter with water that develops into a mudflow or a debris flow. This results in a flow of a slurry rock and mud mixture which can pick up trees, houses, vehicles, etc. and can block bridges and roads. Earthflow is another important landslide process where the fine-grained matter falls under gravity. These are a lot like mudflows, but they typically move very slowly, and these landslides begin with the increase of pore pressures in finely grained mass.

What is an Avalanche

Avalanche is a type of landslide that occurs in snowy regions. Therefore, we can call it a snowslide. This type of landslide occurs when a cohesive slab of snow that is lying upon a weaker layer of snow fractures and slides down a steep slope. Usually, the initiation of a snowslide occurs due to a very small force acting on a snow layer. But the disturbed snow portion can rapidly grow into a large mass of snow. This is due to the entrainment of more snow. Moreover, when an avalanche moves very fast, some of the snow mixes with air and forms a powder snow avalanche. It is a type of gravity current.

The formation of the initial snowpack may occur due to the weakening of the snowpack on a snow layer or increased load due to precipitation. These avalanches are called spontaneous avalanches. In addition, an avalanche can also be initiated due to human activities and biological activities (natural reasons).

Primarily, an avalanche is composed of snow and air. But, upon the rapid growth of the snowpack, it has the ability to entrain trees, ice, rocks, etc. on the way. Some common types of avalanches include slab avalanche, powder snow avalanche, wet snow avalanche, etc.

Difference Between Landslide and Avalanche

Definition

A landslide is a form of mass wasting that includes the movement of a large area of land under the force of gravity while an avalanche is a type of landslide that occurs in snowy regions. 

Flowing matter

While the mass in landslides contains soil, rocks, or mud, avalanches are made of snow and air.

Occurrence

Landslides happen on land with steep slopes while avalanches happen in snowy regions where snowpacks are weakly held by snow layers.

Conclusion

Landslides and avalanche are processes that involve the movement of a large mass of matter from one place to another under the force of gravity. The key difference between landslide and avalanche is that landslides occur on land, whereas avalanche occurs on snow.

Reference:

1. “Landslide.” National Geographic Society, 9 Oct. 2012, Available here.
2. “Avalanche.” Wikipedia, Wikimedia Foundation, 26 May 2020, Available here.
3. “Landslide.” Wikipedia, Wikimedia Foundation, 8 Apr. 2020, Available here.

Image Courtesy:

1. “Goodell Creek Debris Avalanche” By G310Luke – Own work (Public Domain) via Commons Wikimedia
2. “Avalanche on Everest” By Chagai at English Wikipedia – Transferred from en.wikipedia to Commons (Public Domain) via Commons Wikimedia