Rising Avalanche Risks

Rising Avalanche Risks

For Prelims: Avalanche, Earthquake, Himalayas, Avalanche Monitoring Radar
For Mains: Causes of Avalanches and Measures to Mitigate Its Risks

Why in News?

A massive avalanche in Uttarakhand’s Chamoli district buried people and properties under snow and debris. Warmer temperatures, increased rainfall, and reduced snowfall are altering snow conditions, thereby raising the risk of avalanches in the Himalayas.

What is an Avalanche?
An avalanche is the rapid descent of snow, ice, and debris down a mountain slope, often carrying earth, rocks, and rubble, which can cause significant destruction.
Avalanche risks peak from December to April due to heavy snowfall during winter and the spring thaw, which weakens the snow layers.

Types of Avalanches:

• Loose Snow Avalanche: Initiates from a single point where snow isn’t well bonded, spreading in an inverted V-shape. It tends to be less dangerous because of its lower speed and volume.
• Slab Avalanche: Occurs when a cohesive snow slab breaks off from the underlying layers, reaching speeds of 50-100 km/h and causing substantial destruction.
• Gliding Avalanche: Involves the sliding of snowpacks down a smooth surface, such as rock or grass, creating a broad fracture line.
• Wet-Snow Avalanche: Triggered by rising temperatures or rain, where meltwater weakens the snow bonds.

Causes of Avalanches:
Natural Causes:

• Snow Accumulation: Continuous or excessive snowfall increases snowpack weight, leading to instability (e.g., Himachal Pradesh avalanche, January 2020).
• Windy Conditions: Wind can enhance instability by depositing snow on slopes.
• Weak Snow Layers: Temperature changes weaken the snowpack, making it more prone to avalanches.
• Earthquakes: Seismic activity can destabilize snow layers, as seen during the 2015 Nepal earthquake, which triggered avalanches in Langtang Valley.

Human-Induced Causes:

• Deforestation: The removal of trees destabilizes slopes, increasing the likelihood of avalanches, as seen in Himalayan road projects.
• Adventure Tourism: Activities like skiing, snowboarding, and mountaineering can trigger avalanches by disturbing the snowpack. For instance, in February 2024, skiers in Gulmarg triggered an avalanche by skiing in a non-designated area.
• Global Warming: Rising global temperatures cause more frequent freeze-thaw cycles, which heighten avalanche risks.

How Avalanches Differ from Landslides:

Basis	Avalanche	Landslide
Definition	A landslide that occurs in snowy regions, involving snow and air movement.	A mass of soil, rocks, or mud moving under gravity.
Causes	Snow accumulation, weak snowpack, temperature fluctuations, wind, earthquakes.	Earthquakes, volcanic eruptions, heavy rains, floods, deforestation, wildfires.
Flowing Matter	Snow and air.	Soil, rocks, or mud.
Occurrence	Occurs on slopes with weak snow layers.	Happens on land with steep slopes.
Speed of Movement	Extremely fast (up to 250 miles per hour in extreme cases).	Can be fast (like avalanches) or slow-moving.

Why the Himalayas Are More Prone to Avalanches:

• Rising Temperatures: The Himalayas are warming faster than other regions, causing glacier melt and retreating snowlines. Avalanches have increased significantly since the 1970s in the western Himalayas.
• Wetter Snow: Higher temperatures result in more rain than snow, which makes the snowpack wetter and more unstable.
• Permafrost Melting: The thawing of permafrost causes water accumulation, making ice layers more prone to sliding.
• Increased Wind Speeds: Higher temperatures lead to stronger winds, which increase snow transport and destabilize snow layers.
• Steep Slopes: The steep, rugged terrain of the Himalayas makes it easier for snow to slide down under gravity.
• Seismic Activity: The Himalayas are seismically active, and earthquakes can trigger avalanches by shaking unstable snow layers.

Karakoram Anomaly:

The Karakoram Anomaly refers to the unusual stability or slight mass gain of glaciers in the Karakoram Range, contrary to the general global trend of glacier retreat caused by climate change. The Karakoram Range spans across Pakistan, India, Afghanistan, Tajikistan, and China.

How to Mitigate Avalanche Risks:

• Early Warning Systems (EWS): By monitoring snow conditions using sensors and satellites, EWS can detect weak snow layers and issue alerts to reduce avalanche risk. For example, India’s first avalanche monitoring radar was installed in Sikkim in 2022, capable of detecting avalanches within 3 seconds of initiation.
• Snow Tests: Regular snow tests can assess snowpack stability and predict avalanche risks.
• Defensive Structures: Snow sheds can be constructed along transportation routes to shield vehicles from falling snow, and wall reinforcements can deflect avalanches away from buildings.
• Dual-Purpose Infrastructure: Building dams to protect against flooding and debris flows caused by snowmelt can provide year-round disaster mitigation.
• Artificial Avalanche Triggering: Controlled explosions can trigger small avalanches to prevent larger ones, protecting roads, settlements, and ski resorts.
• Afforestation: Promoting forest growth can help naturally control avalanches by stabilizing slopes over time.

Conclusion:
Global warming is exacerbating avalanche risks in the Himalayas by altering snowpack stability, increasing rainfall, and accelerating glacier melt. Given the region's steep terrain and seismic activity, proactive measures such as early warning systems, protective infrastructure, and controlled avalanche triggering are essential to mitigate risks and protect vulnerable communities.

Drishti Mains Question:
Discuss how climate change is increasing avalanche risks in the Himalayas and suggest mitigation strategies.

UPSC Civil Services Examination, Previous Year Question (PYQ):
Mains
Q. Bring out the relationship between the shrinking Himalayan glaciers and the symptoms of climate change in the Indian subcontinent. (2014)

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