Natural disasters force us, as engineers, to question our role in a rapidly changing world. Following the Mw 7.8 earthquake which struck Nepal in April 2015, I had the opportunity to visit the country as part of the UK-based Earthquake Field Investigation Team (EEFIT) to assess the damage. There is much to be learned from the disaster, but one lesson we must drive home is that resilient infrastructure is essential in disaster zones.
The epicentre of Nepal’s earthquake was located near the town of Gorkha, approximately 80km west of Kathmandu. It is not difficult to understand the devastating effect of the disaster on a country with slow economic growth, an unemployment rate of more than 40% and a reliance on agriculture, tourism and international aid to support its economy. With more than 7,500 fatalities, as well as significant damage to unreinforced masonry, historic structures and temples, it is estimated that the economic losses of the earthquake could be as high as US$10bn. Preliminary estimations suggest the cost of rebuilding is nearly US$5bn.
The frequency and impact of natural disasters globally is increasing – this can be measured by loss of life as well as economic costs. This trend is set to continue due to risks associated with rapid urbanisation and environmental degradation. As engineers, we must be aware of the importance of seismic safety in the infrastructure we design.
Consequences of vulnerable infrastructure
The EEFIT team visited sites at Kathmandu, Bhungmati, Khokana, and UNESCO World Heritage Site Bhaktapur, as well as mountainous regions. Many collapsed and damaged buildings were seen in the older parts of the towns, but we observed that concrete frames with brick infill were better able to withstand the impact. Initial conclusions suggest that damage may have been induced by soft storey buildings, ground liquefaction, induced ground movement or a combination of all these factors.
The earthquake’s impact was greatest on remote mountain communities due to landslides and rockfall triggered by the seismic shaking. Concerns were raised about the stability of these slopes with the subsequent onset of monsoon rainfall. Many communities now face a potentially dangerous situation with slopes already near failure and wetting due to incessant monsoon rainfall. Hence seismic and urban resilience strategies need to consider the possibility that landslides could cut off communities from post-disaster support. Rapid landslide assessment work is urgently needed. Such vital work could protect communities and infrastructure from future disasters.
During the trip I was also struck by the resilience of the people who had lost everything. Conversations centered on the loss of memories associated with the ruined Dhoka Durbar Square heritage site in Bhaktapur. Despite it all, people were determined to carry on, searching for their belongings in piles of rubble. Huge efforts were being made to clear the rubble by hand off the narrow streets and to sort the materials to reuse them for construction.
Engineers are essential
It was overwhelmingly moving to have people ask the EEFIT team for advice on rebuilding their homes. A primary school teacher told us that she did not need food or money, but expertise on how to save her house and belongings in future.
The full support of engineers will be required in rebuilding, retrofitting and redesigning safer structures for Nepal’s schools, hospitals, bridges, infrastructure and houses to survive catastrophic events like this. In future, resilient infrastructure will make it easier to cope with extreme events. This requires engineers who understand risk, can devise appropriate mitigation strategies and who will promote a new culture of safety and collaboration.