When Nepal was hit by consecutive earthquakes in April and May 2015, around 9,000 people were killed and many thousands more were injured. Multistory buildings, homes and temples, not built to withstand the tremors, collapsed. Damage and reconstruction costs were in the billions.
Nearly eight years later, the Nepalese government and international aid organizations have helped rebuild hundreds of thousands of homes across the Himalayan country, preparing these buildings to withstand the shock of the next inevitable earthquake.
But in Turkey and Syria — where the death toll and destruction are much higher — this is expected to be a far greater challenge.
Urgent global need for disaster-resilient housing
The aim for reconstruction groups is to "build back better," often using "locally available, widely known, and cost competitive" building techniques, said Elizabeth Hausler, the founder and CEO of US-based NGO Build Change, which is active in Asia, Latin America and the Caribbean.
In Nepal, homeowners were required to be involved in the rebuilding effort. For the Japan International Cooperation Agency, that included a strong focus on community networks and "mobile masons." These local engineers were trained in seismic-resistant building by Japanese experts, who are well-versed in designing earthquake-proof buildings. Mobile masons traveled from village to village, helping with reconstruction and passing on their newly learned techniques.
"The mobile masons helped us to build our house brick-by brick, which is stronger and will not collapse even if another earthquake hits," said Resham Binita Bhujel, a single mother of five young children in a village northeast of Kathmandu, in a 2020 JICA progress report.
The majority of the more than 1 million buildings damaged or destroyed in rural Nepal featured traditional stone masonry and mud-mortar techniques, on average two stories in height. After surveying the damage, Build Change found that many damaged buildings didn't necessarily have to be torn down and replaced.
"Much of the single family housing damaged in the earthquake could be repaired and strengthened for around $3,000," Hausler told DW. "Given these buildings would cost $20,000 to replace, the cost-benefit of strengthening them was compelling." Through retrofitting — repairing and strengthening unsafe buildings — builders reinforced weak walls, strengthened columns and other support structures and replaced inferior building materials.
To be eligible for government assistance, homeowners were required to use earthquake-resilient measures in their reconstruction, said Kamran Akbar, a disaster risk management specialist with the World Bank based in Kathmandu. "There was no restriction on any construction materials or methods as long as they met the minimum seismic resilience requirement," he said.
Many of the solutions used in Nepal by Build Change and other organizations relied on confined masonry, which uses evenly spaced horizontal and vertical beams and columns of reinforced concrete to better support homes during earthquakes.
In a YouTube video published by Build Change, an engineer in Haiti compares the reinforcements to interlaced fingers which resist external pressure much more efficiently than two closed fists side by side.
There's a critical need for disaster-resilient housing, not just in Turkey and Syria but globally. Hausler said up to 40% of the world population will be living in vulnerable housing by 2030. "It's one of the urgent challenges of our time, affecting almost the same number of people as those that lack access to basic health care," she said.
Earthquakes are part of daily life in Chile
Chile, where millions of people live on an extensive system of fault lines, has been able to successfully address that challenge. Near-daily seismic events are a "constant reminder that we are on shaky ground," said Magdalena Gil, a post-disaster reconstruction researcher at the Research Center for Integrated Disaster Risk Management, CIGIDEN. "Every Chilean who is 30 years old has gone at least through one main [earthquake] event."
"Fortunately, Chile has strict seismic design codes," said Gabriel Gonzalez, CIGIDEN's deputy director, crediting these regulations for the fact that only one building collapsed during the last major quake, a magnitude 8.8 tremor, in February 2010. The building, a 15-story residential structure that had just been completed in the central city of Concepcion, was still largely empty. Some 500 people were killed throughout the country as a result of the quake and the ensuing tsunami.
Over the years, the construction sector — in Chile and other seismically active regions — has developed techniques designed to reinforce modern high-rises. Gonzalez said there are no height limits for buildings in Chile's seismic design codes. Instead, these high-risk buildings use reinforced concrete columns and beams, supported by steel frames, to develop the flexibility to withstand strong quakes. The concrete beams may break, but the steel reinforcement columns are designed to stay standing and prevent complete collapse.
Surprise inspections at construction sites also ensure that design codes are being followed to the letter. These codes, said Gil, have been steadily improved after every major earthquake dating back to the magnitude 9.5 disaster in May 1960, the most powerful seismic event ever recorded.
'Building codes are not magic'
Gonzalez told DW that since the 2010 earthquake, the government's focus has also shifted to improving cooperation between emergency response agencies. He added that risk anticipation and disaster preparedness — emergency drills, education and retrofitting older infrastructure — are playing a greater role to mitigate the impact of future quakes and other natural disasters.
With some of the strictest design codes in the world, Chile is seen as a model of earthquake preparedness and response alongside Japan. "But the building codes are not magic," said researcher Gil, pointing out that Turkey, for example, also has building codes that meet modern standards.
"You also need to look at the different institutions and processes and actors that enforce the codes," she said. "The code is meaningless without this network. If you don't enforce the codes, then it's just paper."
Turkey, Syria face rebuilding challenges
Experts believe weak enforcement of building codes — in part to help fuel a construction boom and economic growth over the last two decades — was at least partially responsible for the widespread devastation in Turkey after the recent earthquakes.
Periodic amnesty policies since the 1960s have allowed Turkish construction companies and individuals to pay a fine to avoid having to bring their buildings up to code. At the time of the latest amnesty in 2018, the Environment, Urbanization and Climate Change Ministry, responsible for enforcing building codes, said more than half of all buildings in Turkey were not in compliance with current standards.
For Gonzalez, seeing single buildings still standing amid a vast debris field in the news footage from Turkey was "a clear picture that some buildings have not followed the regulations."
As Turkey and Syria rebuild, authorities will have to consider what needs to change to keep their homes and towers standing during the next major earthquake or climate-related disaster. One estimate by the Turkish Enterprise and Business Confederation has put the reconstruction costs at more than $70 billion (€65.2 billion).
"It is of absolute necessity that not only new construction be made disaster resilient, but the existing ones are retrofitted to face disaster challenges," said Akbar. The latter option is often preferred: it can be less expensive, and quicker to realize.
It's also better for the environment: in a global study due out later this year, Build Change found that, on average, retrofitting vulnerable housing could avoid about 60% of the embodied carbon associated with new construction. Making housing more resilient against the impact of earthquakes can also help protect against other hazards, such as hurricanes, windstorms and flooding.
Edited by: Tamsin Walker, Sarah Steffen