Landslide Hazards in India: Himalayan Vulnerability and Notable Disasters

India faces a persistent threat from landslides, particularly in its mountainous regions. Every year, these geological hazards claim hundreds of lives and cause devastating economic losses. Understanding the vulnerability of different regions and learning from past disasters is essential for building safer, more resilient communities in landslide-prone areas.

Why India is vulnerable to landslides 🔗

India’s susceptibility to landslides stems primarily from its unique geological setting. The Himalayas, formed by the collision of Indian and Eurasian plates, experience continuous stress as the Indian plate moves northward at approximately 5 cm per year. This ongoing tectonic activity makes rocks in the region fragile, weak, and highly susceptible to both landslides and earthquakes.

The Eastern Himalaya experiences convergence at a rate of approximately 3.5-6 cm per year, resulting in accumulated strain energy that manifests as earthquakes and slope failures. The region’s steep slopes, intense rainfall, rapid erosion, and weathering of rock masses further reduce the stability of natural slopes, creating conditions ripe for landslides.

Where landslides strike most frequently 🔗

Landslides and avalanches affect approximately 15% of India’s landmass, spanning multiple geographical regions with distinct characteristics.

The Himalayan belt 🔗

The Himalayas stand out as the most landslide-prone region in India. The Eastern Himalayan region comprises Sikkim, Bhutan, Arunachal Pradesh, and the Eastern Himalayan Syntaxis, forming part of one of the most seismically active zones globally. The northwestern and northeastern Himalayan regions experience landslides of every type and scale.

The Northeastern region faces a particularly wide array of landslide issues, causing recurring economic losses in states like Assam, Meghalaya, Darjeeling, and Sikkim. These areas are characterized by immature and rugged topography, fragile rock conditions, high seismicity from proximity to plate margins, and heavy rainfall.

Western Ghats and southern regions 🔗

The Western Ghats and Nilgiris face distinctive landslide challenges characterized by lateritic caps, especially on steep slopes overlooking coastal areas. The Eastern Ghats and Vindhyan ranges also experience landslide activity, though to a lesser extent than the Himalayan regions.

Devastating landslides that changed India 🔗

India has witnessed numerous catastrophic landslides that have shaped its approach to disaster management.

The Malpa tragedy of 1998 🔗

On August 18, 1998, a massive landslide wiped away the entire village of Malpa in Pithoragarh district, Uttarakhand, claiming 221 lives. Among the victims were 60 Hindu pilgrims traveling to Tibet as part of the Kailash Mansarovar Yatra, including noted Indian dancer Protima Bedi.

The rockfall, which began on August 16, continued until August 21. The disaster occurred due to steep, almost vertical slopes, proximity to major tectonic plates, heavy rainfall into porous rock, and stress on rock formations. The landslide generated around one million cubic meters of rock fall and debris flow, partially blocking the Sharda River.

The Kedarnath catastrophe of 2013 🔗

In June 2013, a cloudburst centered on Uttarakhand triggered devastating floods and landslides, becoming India’s worst natural disaster since the 2004 tsunami. The disaster unfolded in two phases over June 16-17, 2013.

The catastrophe killed more than 5,000 people in Uttarakhand, with the vast majority of fatalities resulting from a lake outburst and debris flow disaster originating above Kedarnath village. The rainfall received that month was about 375 percent more than the normal monsoon rainfall for the region.

Heavy rainfall of approximately 390 mm between June 10-17 immediately following a 4-week period of rapid snow cover depletion triggered the disaster. The collapse of the moraine-dammed Chorabari Glacier lake contributed significantly to the flooding. Entire settlements like Gaurikund and Ram Bada were obliterated, while Sonprayag suffered heavy damage and loss of lives.

Other significant events 🔗

India’s landslide history includes the Guwahati landslide (1948), Darjeeling landslide (1968), Mumbai landslides (2000, 2021), Amboori landslide in Kerala (2001), Okhimath landslide (2001), Barpeta landslide (2015), Uttarakhand landslide (2016), Papumpare district landslide (2017), Barak Valley landslide (2020), Manipur Noney district landslide (2022), and Raigad landslide (2023).

Protecting communities through mitigation strategies 🔗

Addressing landslide risks requires comprehensive, multi-layered approaches that combine scientific monitoring, structural interventions, and community engagement.

Hazard mapping and zonation 🔗

Landslide hazard zonation maps at 1:50,000 scale and progressively larger scales for specific areas form the foundation of mitigation efforts. The National Remote Sensing Center, Department of Science and Technology, Council of Scientific and Industrial Research, and Indian Institutes of Technology have conducted extensive work in this area.

Under the National Landslide Susceptibility Mapping program, landslide susceptibility mapping on a macro-scale has been completed for all landslide-prone areas in the Darjeeling-Sikkim Himalaya, covering 7,960 square kilometers and mapping 4,931 active landslides.

Monitoring and early warning systems 🔗

The Landslide Risk Mitigation Scheme provides financial support for site-specific landslide mitigation projects, covering disaster prevention strategy, disaster mitigation, research and development in monitoring critical landslides, and development of early warning systems.

A prototype regional landslide early warning system has been developed through an international collaborative research program, tested in Darjeeling, West Bengal. The system issues experimental daily landslide forecast bulletins to local administration during monsoon periods.

Structural and non-structural measures 🔗

Effective mitigation combines structural interventions with policy measures. Strategies include identifying hazard zones, stabilizing specific slide-prone areas, implementing monitoring systems, and developing codes for excavation and construction in vulnerable regions.

The National Disaster Management Authority has developed comprehensive guidelines covering landslide hazard and vulnerability assessment, risk zonation, remediation practices, research and development, knowledge networks, capacity building, public awareness, and emergency preparedness.

Integrated disaster management 🔗

Since landslide-prone regions largely overlap with earthquake-prone areas, primarily in the northwest and Northeast, integrated approaches to disaster management are essential. This coordination between different hazard management systems enhances overall resilience and reduces vulnerability in these sensitive regions.

What do you think? How can local communities better prepare for landslide risks in vulnerable Himalayan regions? What role should technology play in improving early warning systems and disaster response in remote mountainous areas?

References

1. https://ndma.gov.in/Natural-Hazards/Landslide
2. https://pmc.ncbi.nlm.nih.gov/articles/PMC9245864/
3. https://en.wikipedia.org/wiki/1998_Malpa_landslide
4. https://en.wikipedia.org/wiki/2013_North_India_floods
5. https://link.springer.com/article/10.1007/s11069-015-2076-0
6. https://link.springer.com/article/10.1007/s10346-015-0584-3
7. https://ndma.gov.in/Mitigation_Preparedness/LRMS
8. https://www.indiawaterportal.org/articles/management-landslides-and-snow-avalanches-national-disaster-management-guidelines-national