Le Népal ou comment une catastrophe peut semer la suivante

Nepal faces the consequences of a disaster that has set off another, revealing how one catastrophe can lead to another. Recent images of devastation have led many to believe this latest tragedy was caused solely by an extreme weather event. However, geological studies show that such disasters rarely occur in isolation. They often form part of a chain of events that can unfold over years or even decades. To understand what happened recently in Nepal, we must look back more than a decade to the 2015 Gorkha earthquake. That quake, measuring 7.8 on the Richter scale, was one of the largest in recent history for the country. It claimed thousands of lives and left hundreds of thousands of homes destroyed. But its effects extended far beyond immediate destruction. The earthquake triggered thousands of landslides, rockfalls, and avalanches along much of the Central Himalayas. In many areas, the landscape was permanently altered. Geologists know that a major earthquake does not end when the ground stops shaking. Open fractures in slopes, weakened cliffs, and massive volumes of displaced rock can remain unstable for years. Numerous studies conducted after the earthquake warned that the arrival of the monsoon season would continue to reactivate these movements and increase erosion in affected watersheds. For thousands of residents living in mountain villages, this meant living with a constant sense of insecurity. Roads had disappeared, many houses were uninhabitable, and the slopes that had long provided sustenance and shelter had turned into threats. It is difficult to measure how much this factor influenced population movement, but it is known that the earthquake caused significant displacement and changes in settlement patterns. It is also clear that better-connected and more accessible areas concentrated much of the aid and reconstruction efforts. This brings up a rarely covered issue. During emergencies, the priority is saving lives. It makes sense that temporary shelters, distribution centers, and relief camps are located in accessible areas near roads and relatively flat terrain. In Nepal, as anywhere else, this decision responded to an obvious operational need. Aid needed to reach large numbers of people quickly. However, the logic of emergency response does not always align with the logic of territorial planning. International experience shows that many temporary settlements eventually become permanent. Where roads, electricity, healthcare facilities, and economic opportunities arrive first, it is common for communities to find reasons to stay. It is not hard to imagine that some families who had abandoned particularly affected mountainous areas due to landslides ended up settling permanently in valley floors or near transportation corridors. Although this hypothesis requires specific studies to quantify its extent, it fits with observed mobility patterns following the earthquake and with the role accessibility plays in relocation decisions. And here lies one of the great paradoxes of risk management. Leaving a danger behind does not necessarily mean arriving at a safe place. Valleys offer better communication, a more favorable topography for building, and access to essential services. Yet they also concentrate other risks. These are the spaces through which water flows, where sediments from mountains accumulate, and where many processes generated in highland areas converge. From a geological perspective, a community can shift from being exposed to landslides and to...