In mountainous areas, earthquakes can sometimes be amplified by the shape of the landscape. Research by the University of Twente shows that further from the epicentre, the shape of the terrain’s topography increases the risk of landslides. Closer to the epicentre, it is mainly the strength of the earthquake itself.
Ashok Dahal, a young researcher from Nepal, together with an international team at the University of Twente, has developed a new method to better predict landslides after severe earthquakes. The findings show how certain mountain areas amplify the strength of the earthquake due to their shape, leading to greater damage in specific places.
In the event of an earthquake, the shock wave spreads through the landscape. In some places in the mountains, these waves are amplified by the shape of the hills and mountains, a phenomenon called 'topographical amplification’. This effect makes certain areas particularly vulnerable to landslides. Dahal and his colleagues developed computer models that show exactly where those amplified shock waves end up.
A personal motivation
The research focused on the devastating earthquake in Kathmandu Nepal in 2015, an event close to home for Dahal, who grew up in Nepal. With family and friends in affected areas, he had a personal motivation to carry out this research. With these findings, regions like Nepal may better protect communities from future landslides by understanding how the landscape shapes earthquake impact.
The team found that the landslides are most common in places that are more than 40 kilometres from the earthquake's epicentre. "Our findings show that close to the epicentre, the effect of topography is minor; the quake’s raw strength dominates. But further from the centre, where the earth's movement weakens, topographic amplification becomes much more significant, greatly increasing landslide risk," Dahal explains.
Ten years of research
This knowledge can help countries with mountainous terrain, such as Nepal, in protecting vulnerable regions more effectively. "We have been studying this phenomenon for over a decade, with nearly ten years focused on this particular earthquake," says researcher Mark van der Meijde. "This extensive research, combined with our latest simulation, has provided a wealth of knowledge to improve earthquake impact predictions."
Learn more
Dr Ashok Dahal is an assistant professor in the Department of Applied Earth Sciences at the Faculty of ITC. Prof. Mark van der Meijde is a professor in the same department. The researchers Dahal, Tanyas, Mai, Van der Meijde, Van Westen and Lombardo published their findings in an article, entitled 'Quantifying the influence of topographic amplification on the landslides triggered by the 2015 Gorkha earthquake', in the scientific journal Nature Communications Earth & Environment.
