Explained: What is a landslide, its causes, types, states most prone to it and worst landslides in India | Knowledge News

In one of the deadliest natural calamities in Kerala, a minimum of 123 individuals lost their lives and 128 sustained injuries as massive landslides were set off by heavy rainfall in Wayanad on Tuesday. With numerous people trapped under the debris, there is a growing concern about increasing fatalities. Rescue teams are working tirelessly to save any survivors.

The spot where a landslide occurred due to heavy rain at Chooralmala, Wayanad (Photo credit: PTI)

New Delhi: A natural disaster is a catastrophic event triggered by natural hazards, which are natural processes or phenomena that can lead to devastating consequences, including loss of life, destruction of property, and adverse environmental effects. Examples of natural hazards include earthquakes, hurricanes, droughts, and landslides. In this article, let us look at a landslide, its types, causes, districts more prone to landslides, and a list of the worst landslides in India.

What is a landslide?

Landslides, or landslips or rockslides, encompass various types of mass wasting, including rockfalls, mudflows, slope failures, and debris flows. They can occur in multiple environments, from steep mountain slopes to coastal cliffs and even underwater, where they are known as submarine landslides.

While gravity is the primary force driving landslides, other factors, such as specific environmental conditions and human activities, can contribute to slope instability. Incidents like heavy rainfall, earthquakes, and human interventions like road construction can trigger landslides, but the exact cause is sometimes challenging to identify.

Landslide mitigation is a crucial process involving implementing policies and practices to minimise the impact of landslides. These measures are important in ensuring safety and resilience by reducing the risk of these natural disasters on human lives and infrastructure.

What causes landslides?

Human activities like urban expansion, mining and deforestation worsen landslides. These activities further lead to land degradation and loss of soil stabilisation from vegetation, which are major contributing factors. The influence of climate change and global warming can escalate natural disasters, like extreme weather, thereby increasing the risk of landslides.

Landslides happen when a slope becomes unstable due to various factors. Natural causes of landslides include an increase in water content from rain, snow, or glacier melting, rising groundwater or pore water pressure, erosion by rivers or sea waves, and physical and chemical weathering.

Other natural causes include ground shaking from earthquakes, volcanic eruptions, changes in pore fluid composition, and temperature changes. Human activities, such as deforestation, construction, and agriculture, can worsen landslides.

Additionally, vibrations from machinery or traffic, blasting and mining, and land use and cover changes can also contribute to landslides.

How can you classify landslides?

Landslides, including falls, slides, topples, and flows, can be classified based on their movement type.

Falls: These are sudden movements of soil, debris, and rock that break away from slopes and cliffs due to mechanical weathering, earthquakes, and the force of gravity.

Slides: This type of mass movement involves materials breaking away from the underlying stable material and sliding down slopes.

Topples: Topple failure refers to the forward spinning and movement of large masses of rock, debris, and earth from a slope. This type of slope failure occurs around an axis near or at the bottom of the block of rock.

Flows: This category includes various types of landslides such as earth flows, debris avalanches, debris flows, mudflows, and creep. These can occur seasonally, continuously, or progressively, involving the flow of materials down slopes.

Source: nrsc.gov.in

Source: nrsc.gov.in

States most prone to landslides

District Rank	District	State
1	Rudraprayag	Uttarakhand
2	Tehri Garhwal	Uttarakhand
3	Thrissur	Kerala
4	Rajauri	J&K
5	Palakkad	Kerala
6	Poonch	J&K
7	Malappuram	Kerala
8	South District	Sikkim
9	East District	Sikkim
10	Kozhikode	Kerala
11	Imphal West	Manipur
12	Kodagu	Karnataka
13	Wayanad	Kerala
14	Jammu	J&K
15	Ernakulam	Kerala
16	Mandi	Himachal Pradesh
17	Udhampur	J&K
18	Idukki	Kerala
19	Chamoli	Uttarakhand
20	West District	Sikkim

Source: nrsc.gov.in

Source: nrsc.gov.in

In news

Three landslides happened in Kerala’s Wayanad district after heavy rain. More than 120 people have died, and hundreds are injured. People are using the NDRF and other groups to rescue them.

The first landslide hit Chooralmala village. It destroyed parts of the village, and workers are struggling to help. The floods carried dead bodies, showing how bad the disaster was.

In just four hours, three landslides occurred, making things worse in Chooralmala. Shops, cars, and homes disappeared, and over 200 houses were washed away. The rescue teams still can’t reach Mundakkai because the bridge is gone. The floodwater from Meppadi has made the Chaliyar River rise, which could worsen things. An army team from Wellington, Coonoor, is coming to help.

List of worst landslides in India

In recent years, India has seen several devastating landslides in different regions:

1. Manipur (2022): Two years ago, Manipur experienced landslides due to heavy monsoon rains, which killed over 40 people and injured several others. The landslides affected the state, including the capital city of Imphal and neighbouring regions.

2. Malin, Maharashtra (2014): In 2014, heavy rainfall caused a landslide in Malin village, Maharashtra, resulting in the deaths of over 151 people. The entire village was buried under mud and debris, with more than 40 homes destroyed.

3. Kottayam, Kerala (2019): In 2019, heavy rains and soil erosions triggered a landslide in Kerala, resulting in the deaths of at least 15 people and several others injured.

4. Kedarnath, Uttarakhand (2013): The 2013 Kedarnath landslide, triggered by cloudbursts, resulted in massive floods and killed over 5,000 people. The hilly region faced extensive destruction and took years to rebuild.

5. Shillong, Meghalaya (2011): In 2011, heavy monsoon rains triggered a landslide in Shillong, causing the collapse of a hill section and resulting in the deaths of over 20 people, along with several injuries.

6. Mapla village, Uttarakhand (Then Uttar Pradesh) (1998): In August 1998, consecutive landslides over seven days resulted in the deaths of over 200 people, wiping out an entire village and marking one of the worst human tragedies in India.

7. Darjeeling, West Bengal (1968): On October 4, floods triggered a landslide that severed a 60 km long national highway into 91 segments. The catastrophe resulted in the deaths of over 1,000 people and caused extensive damage to property, infrastructure, and tea plantations.

8. Guwahati, Assam (1948): Heavy rain triggered a massive landslide in September, burying an entire village and resulting in the deaths of over 500 people.

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