Indonesia needs earthquake resistant houses. Building them is a huge challenge



CNN

A deadly earthquake that reduced buildings to rubble in Indonesia’s West Java has once again exposed the dangers of living in poorly built homes in one of the most seismically active zones on the planet.

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

The quake’s shallow depth – just 10 kilometers (6 miles) – added to the strain on structures in West Java, where more than a million people were exposed to very strong earthquakes, according to the United States Geological Survey (USGS).

Visiting the site on Tuesday, Indonesian President Joko Widodo promised that the damaged houses – more than 56,000 of them – would be rebuilt to be earthquake-resistant.

“Houses affected by this earthquake are required to use earthquake-resistant building standards by the Minister of Public Works and Public Housing,” he said. “These earthquakes happen every 20 years. So the houses must be earthquake-proof.”

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

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

A man reacts as rescuers search for victims in an area hit by landslides after Monday's earthquake in Cianjur, West Java province, Indonesia, November 22, 2022.

Indonesia, an archipelago nation of more than 270 million people, sits along the Ring of Fire – a zone around the Pacific Ocean where most active volcanoes are located and most earthquakes occur as 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 building foundations, causing concrete structures to collapse and roofs to cave in. Photographs showed broken remains of metal, timber and bricks. According to the governor of West Java, Ridwan Kamil, most of the dead were crushed or trapped under the debris. Others were killed in landslides.

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

The trip – about 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 with dirt and mud,” she said, adding that she was reunited with her family who survived the earthquake.

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

Indonesian search and rescue team evacuate bodies from damaged buildings in Cianjur Regency, West Java Province, on November 22, 2022.

In Indonesia, houses were traditionally made of organic building materials such as timber, bamboo and thatch due to the country’s hot and humid climate.

These were considered sustainable houses and largely earthquake resistant. However, increased deforestation and the high cost of timber have led people to choose alternative materials, according to a 2009 study on post-disaster reconstruction in Indonesia by the Architectural Science Association.

More and more houses were built of brick and concrete, and while the facade may have looked modern, underneath, the structure did not hold up well, according to the study.

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

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

Seismic structures are designed to protect buildings from collapse and can work in two ways: by making buildings stronger or by making them more flexible so that they sway and slide over the ground instead of collapsing.

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

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

When the earthquake struck in 2015, more than 8,000 people were killed, but the schools, built with traditional techniques and materials from the landscape, such as rubble masonry, did not collapse.

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

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

In Nepal, many people build their houses with mud mortar, which is very fragile, Schildkamp said. “If it is completely unreinforced, there is no additional reinforcement in the building. This is what will fall apart very easily,” he said.

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

Building regulations should prevent the proliferation of junk structures, but in some countries not enough is being done by governments 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, hope is fading to pull more people alive from the rubble of the earthquake.

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

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

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