Indonesia needs earthquake-proof houses. Building them is a big challenge



CNN

A deadly earthquake that reduced buildings to rubble in West Java, Indonesia, has highlighted once again the dangers of living in poorly constructed homes in one of the most seismically active zones on earth.

Since Monday’s quake, survivors have been sleeping outdoors or in temporary shelters away from collapsing homes as aftershocks rattle buildings already damaged by the magnitude 5.9 quake that killed at least 271 people.

The earthquake’s shallow depth — just 10 kilometers (6 miles) — increased pressure on structures across West Java, where more than a million people experienced very strong shaking, according to the United States Geological Survey (USGS).

During a site visit on Tuesday, Indonesian President Joko Widodo pledged that damaged homes – more than 56,000 of them – would be rebuilt earthquake-proof.

“Houses affected by this earthquake must meet earthquake-proof building standards set by the Minister for Public Works and Public Housing,” he said. “These earthquakes happen every 20 years. So the houses should be earthquake-proof.”

But in a developing country where about 43% of the rural population lives in largely unsafe and poorly constructed homes, the task of constructing earthquake-resistant buildings remains a major challenge.

More than 61,000 people had been displaced as of Thursday, according to the National Agency for Disaster Management (BNPB) – and experts say the damage could have been mitigated with proper infrastructure.

A man reacts as rescue workers search for victims in a landslide-hit area after Monday's earthquake struck in Cianjur, West Java province, Indonesia, November 22, 2022.

Indonesia, an archipelagic nation of more than 270 million people, lies on the Ring of Fire — a band around the Pacific Ocean where most active volcanoes are and most earthquakes occur when tectonic plates push against each other, causing tremors.

Of the 271 people killed in Monday’s quake, at least 100 were children, many of whom were at school when the quake struck. A 6-year-old boy was pulled alive from the rubble of his home two days later, but many others were not so lucky.

The earthquake shook the foundations of buildings, causing the concrete structures to collapse and roofs to collapse. Photos showed broken pieces of metal, wood and brick. According to West Java Governor Ridwan Kamil, most people were killed or trapped under rubble. Others were killed in landslides.

Cleo Gaida Salima said that when she heard about the quake, she tried to call her mother in Cugenang, Cianjur, but when she didn’t answer, she decided to go there by motorbike from her home in Bandung.

The journey – around 65 kilometers (40 miles) – usually takes less than two hours. But with the roads completely blocked by landslides, it took her 24.

“All the houses were covered in dirt and mud,” she said, adding that she was reunited with her family, who survived the quake.

“We all cried from emotion and happiness,” she said. “Our whole family immediately ran to save themselves. The earthquake was very strong.”

Indonesian search and rescue team evacuates the bodies from destroyed buildings in Regency Cianjur in west Java province on November 22, 2022.

In Indonesia, due to the country’s hot and humid climate, houses have traditionally been built from organic building materials such as wood, bamboo and thatched grasses.

These were considered sustainable homes and largely durable in the event of an earthquake. However, according to a 2009 study by the Architectural Science Association on post-disaster reconstruction in Indonesia, increasing deforestation and the high cost of wood prompted people to turn to alternative materials.

More homes were being built of brick and concrete, and while the facade looked modern, the structure underneath was poorly held together, the study found.

In addition, the poor quality of concrete and poor steel reinforcement make these structures increasingly vulnerable to collapse during an earthquake – while causing maximum injury due to the weight of the materials, the report said.

A man stands near houses damaged after an earthquake in Cianjur, West Java province, Indonesia, November 21, 2022.

Earthquake-resistant structures are designed to protect buildings from collapsing and can work in two ways: by making buildings stronger, or by making them more flexible so they sway and slide over the swaying ground rather than crumbling.

Architects have been developing this technology for decades, and engineers often adapt materials and techniques locally to the region.

Architect Martijn Schildkamp, ​​​​​​founder and director of Smart Shelter Consultancy, said his company helped build about 20 schools in earthquake-prone Pokhara, in central Nepal, seven years before a major earthquake struck.

When the 2015 earthquake struck, more than 8,000 people died, but the schools, built using traditional techniques and materials from the landscape like rubble masonry, did not crumble.

“Our schools didn’t collapse,” he said. “They only suffered cosmetic damage.”

He said that in developed countries like Japan, knowledge, infrastructure and money are readily available to construct earthquake-resistant buildings, but the high cost of constructing such structures makes it more difficult in developing countries.

In Nepal, many people build their homes with clay mortar, which is very brittle, Schildkamp said. “If it’s completely unreinforced, there’s no additional reinforcement in the building. It’s going to collapse very easily,” he said.

Schildkamp’s team used cement mortar and inserted horizontal rebar into the structure to strengthen it, rather than vertical ones.

Building codes should prevent the proliferation of poorly built structures, but in some countries governments are not doing enough to enforce the rules, Schildkamp said.

“We need knowledge and strategy in these countries. And we need governments to make these building codes mandatory,” he said.

In West Java, hopes of pulling more people alive from the rubble of the earthquake are fading.

Aftershocks are also complicating efforts, and residents now live in fear that the next disaster could bring down their unstable homes again.

While President Widodo said the government would award up to $3,200 each in compensation to owners of badly damaged homes, many families in Cianjur lost everything. And now they face the nearly impossible task of rebuilding.

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