Understanding Himalayan Landslides: Why The Mountains Keep Slipping?
The mountains have always moved. The question is how much we are helping them along. There is something depressingly strange about watching a mountain disappear, watching it take away with it a solid ecosystem, few infrastructure, some memories and many more lives.
I have seen roads we went for morning walks, suddenly covered in mud. A tree falling right in front of my door. A house that stood on a hillside for decades, buried under rocks and soil. Losing connectivity with the outside world, with no ration for days. And then, a few days later, the photographs arrive. A road split open in Himachal Pradesh. A hillside collapsing in Uttarakhand. A village cut off in Nepal. A stretch of highway buried in Darjeeling.
Every monsoon, the locations change. The headlines change. The death toll changes.
The landslide, however, is not new. The Himalayas have been sliding, cracking, eroding and reshaping themselves for millions of years. What is changing is the environment around them, and increasingly, the question is not simply, why do landslides happen in the Himalayas?
It is: What happens when a naturally unstable mountain range meets roads, tunnels, hydropower projects, towns, tourism and a changing climate?
Why do the mountains in Himalaya move?
It is easy to look at a landslide and think something has gone terribly wrong.
Geologically, movement is part of how the Himalayas work. The range that was created by the collision of the Indian and Eurasian tectonic plates are still moving towards each other.
The Himalayas continue to rise, while rivers, rainfall, glaciers and gravity continuously wear them down. This creates a strange balance. The mountains are being pushed upwards while simultaneously being carved down. The rocks are relatively young and, in many places, heavily fractured. The slopes are steep. Rivers cut deeply through valleys. Earthquakes periodically shake the region.
Then comes rain. Water enters cracks in rocks and soil. Saturated soil becomes heavier. The strength holding particles together can decrease. Rivers can undercut the bottom of a slope.
Eventually, gravity wins, and that is a landslide. All of this can happen without a road, hotel or dam anywhere nearby. This is important because not every Himalayan landslide is caused by humans. Some are simply the result of a mountain range that is still being built and eroded at the same time.
Not all Himalayan landslides are the same
Not every Himalayan landslide has the same story
A landslide in Himachal Pradesh isn't necessarily happening for the same reasons as one in Darjeeling or Nepal. The Himalayas are not one uniform landscape. Geology, rainfall, elevation, vegetation, slope angle, river systems, seismic activity and patterns of human settlement vary considerably across the region. So rather than talking about the Himalayan landslide as if there is one common cause, it is more useful to look at how different regions experience the risk.
Himachal Pradesh & Uttarakhand
Steep, young and fractured slopes already make these regions naturally prone to landslides. Intense rainfall, road cutting, construction and altered drainage can further weaken slopes and increase instability.
Darjeeling & the Eastern Himalayas
Very high monsoon rainfall is a major trigger. Slopes can become saturated quickly, while roads, settlements and changing drainage patterns can make them more vulnerable.
Nepal
Landslide risk varies greatly from east to west, depending on geology, rainfall and terrain. Mountain roads, settlements, deforestation and poor drainage can add pressure to naturally unstable slopes.
And then there are the situations where several triggers arrive together. A slope might already be weak. Heavy rain saturates it. A road has been cut into its side. Vegetation has been removed. Water is no longer draining along its natural path. Eventually, the slope gives way. So when we ask whether a particular landslide was caused by climate change or construction, the answer isn't always one or the other.
Sometimes it is both.
Then we started building on the slopes
The Himalayas are home to millions of people making it difficult for the landscape to be left untouched. People need roads to reach hospitals, they need electricity, villages need bridges, farmers need to move produce, children need to reach schools, and mountain communities need economic opportunities.
The problem begins when development assumes that a mountain behaves like a flat piece of land.
Road construction is one of the most visible examples. To build a road through a mountain, you often have to cut into the slope.
That changes the slope's geometry.
Trees and vegetation may be removed.
Excavated material has to go somewhere.
Drainage has to be redesigned.
And if the road is widened, the process happens again.
None of this guarantees a landslide, but on an already fragile slope, these interventions can alter its stability. The same question applies to tunnels, hydropower projects, buildings and other large infrastructure. Blasting and excavation can disturb rock, causing changes to drainage which can redirect water. Heavy structures add loads to slopes and construction debris can end up in places where it can later be washed downhill.
Climate change is changing the background conditions
The Himalayas are warming, glaciers are retreating and many glacial lakes are expanding. This matters for landslides, but also for another hazard: glacial lake outburst floods, or GLOFs. A lake formed by melting glacier ice can grow behind a natural dam made of rock and debris. If that dam fails, enormous quantities of water can move rapidly downstream, just like what happened in Nepal.
That is a different disaster from a rainfall-triggered landslide.
But in the Himalayas, hazards rarely exist in isolation. A landslide can block a river. A flood can destabilise a slope. Heavy rainfall can trigger several landslides at once. An earthquake can weaken slopes that become more vulnerable during the next monsoon.
The 2013 Kedarnath disaster is a stark example of how multiple hazards can converge. Extreme rainfall, flooding and landslides combined to create a disaster far greater than any one of these hazards alone.
Nepal has seen similar cascading risks, where intense rainfall and landslides can block rivers, damage roads and isolate communities, while glacial lakes and changing mountain conditions add another layer of uncertainty.
This is why the future of Himalayan disasters is unlikely to be about one single hazard. It is increasingly about multiple hazards interacting with one another — sometimes turning one event into a chain reaction.
But in the Himalayas, hazards can interact. A landslide can block a river. A flood can destabilise a slope. Heavy rainfall can trigger several landslides at once. An earthquake can weaken slopes that become more vulnerable during the next monsoon. This is why the future of Himalayan disasters is unlikely to be about one single hazard. It is increasingly about multiple hazards interacting with one another.
So, are landslides in Himalayas going to get worse?
There is no simple answer. Landslides themselves are not new, and not every future landslide will be larger or more frequent than those of the past. But several conditions that influence landslide risk are changing.
Extreme rainfall events can be intense.
Glaciers are retreating.
Glacial lakes are changing.
Mountain towns are expanding.
Infrastructure is increasing.
Tourism is growing in many destinations.
Climate change adds uncertainty to the rainfall and temperature patterns on which mountain communities have traditionally depended.
The result is not that “the Himalayas are going to collapse.” That makes for a dramatic headline, but it isn't a useful scientific description. The Himalayas will still be here. The question is whether the places where people live and travel will become increasingly exposed to unstable slopes and other hazards.
Joshimath’s Cracked Homes
Joshimath’s cracks are linked to its location on old landslide debris and a relatively weak, unstable foundation, making the town naturally prone to subsidence. Heavy rainfall, drainage problems and increasing construction have likely added pressure, while experts have also examined the role of nearby hydropower and tunnelling activity.
Tourism brings another layer
Tourism is slightly more complicated, because tourism also brings things mountain communities need.
Jobs.
Income.
Restaurants.
Homestays.
Transport.
Local guides.
Handicrafts.
Small businesses.
For a village with limited economic opportunities, tourists can be important. So, the answer cannot simply be: Stop tourism. However, tourism changes the physical landscape when visitor numbers grow faster than infrastructure. A village that once had a few hundred visitors can suddenly have thousands.
More visitors require more rooms. → More rooms require water. → More water requires pipelines and storage. → More people mean more sewage and waste. → More cars mean more parking and wider roads. → More electricity means more infrastructure.
A small mountain settlement can begin to behave like a city without ever having been planned as one. This is where carrying capacity becomes important. How many people can a place accommodate without overwhelming its water, waste, roads, drainage and ecological systems?
And perhaps more importantly: Where should those people be accommodated?
A hotel on a stable terrace is not the same as a hotel constructed on a vulnerable slope.
A well-designed homestay using an existing building is not necessarily comparable to clearing a forest and constructing a large resort.
A traveler arriving by public transport is not creating the same infrastructure demand as dozens of tourist vehicles climbing the same narrow mountain road.
Tourism isn't one thing.
Its environmental footprint depends enormously on how it is organised.
The mountain will move, what we do around it matters
Perhaps that is the most important thing to take away from the landslide crisis in the Himalayas. The mountains were never static. Landslides are part of the landscape's story, but our roads, towns, dams, hotels, vehicles and changing climate are now becoming part of the story too. And that is where the conversation becomes less about whether we should build or whether we should stop tourism altogether, and more about how we build, how we plan and how we travel.
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