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



CNN

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

Since Monday’s quake, survivors have been sleeping on the streets or in shelters away from homes vulnerable to collapse, while aftershocks have rattled buildings already affected by the magnitude-5.9 quake that killed at least 310 people, according to the head of the National Bureau of Disaster Management (BNPB).

Another 24 people are missing, Lieutenant General Suharyanto said Friday.

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

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

“The homes affected by the earthquake must use earthquake-resistant building standards according to the Minister of Public Works and Housing,” he said. “These earthquakes happen every 20 years. The houses must therefore be earthquake-resistant.”

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

More than 61,000 people were displaced on Thursday, according to the National Agency for Disaster Management (BNPB), and experts say the damage could have been mitigated by proper infrastructure.

Indonesia, an archipelago of more than 270 million people, lies along the Ring of Fire – a belt around the Pacific Ocean where most of the active volcanoes lie and most earthquakes occur as tectonic plates push against each other, causing quakes.

Of the 310 people killed in Monday’s quake, at least 100 were children, many of whom were in school when the quake hit. 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 concrete structures to collapse and roofs to collapse. Pictures showed bits of metal, wood and bricks. According to West Java governor Ridwan Kamil, most people were crushed or trapped under the rubble. Others died in landslides.

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

The journey – about 65 kilometers (40 miles) – usually takes less than two hours. But with 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 with emotion and happiness,” she said. “Our whole family immediately ran to save themselves. The earthquake was very strong.”

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

In Indonesia, houses were traditionally built from organic building materials, including wood, bamboo, and reed grasses, due to the country’s hot and humid climate.

These were considered durable homes, and largely sustainable in the event of an earthquake. However, increased deforestation and the high cost of wood 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 homes were built of brick and concrete, and while the facade may have looked modern, the structure underneath was poorly held together, the study said.

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

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

Earthquake-resistant 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 above the vibrating ground instead of 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 firm helped build about 20 schools in earthquake-prone Pokhara, Nepal’s central region, seven years before a major earthquake.

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

“Our schools have not collapsed,” he said. “They only suffered some cosmetic damage.”

He said that in developed countries such as 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 homes with mud mortar, which is very brittle, Schildkamp said. “If it is completely unreinforced, there is no additional reinforcement in the building. This is what will collapse very easily,” he said.

Schildkamp’s team used cement mortar and placed horizontal reinforcement piles in the structure to strengthen it, instead of vertical ones.

Building codes are supposed to prevent the spread of shoddy construction, but in some countries governments aren’t doing enough to enforce the rules, Schildkamp said.

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

In West Java, hope of getting more people alive from the earthquake remains is fading.

Aftershocks also complicate 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 compensation of up to about $3,200 each to owners of severely damaged homes, many families in Cianjur lost everything. And now they face the almost impossible task of rebuilding.

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