Indonesia needs earthquake resistant homes. Building them is quite a challenge

CNN
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A deadly earthquake has reduced buildings to rubble West Java, Indonesia He once again exposed the dangers of living in poorly constructed homes in one of the most seismically active regions on the planet.

Since Monday’s quake, survivors have been sleeping in the open or in shelters far from homes in danger of collapsing as aftershocks rattled buildings already damaged by the 5.9-magnitude quake that killed at least 310 people, according to the head of the National Disaster Management Agency. in the country (BNPB). ).

Lieutenant General Suharyanto said Friday that 24 other people were still missing.

The quake’s shallow depth — just 10 kilometers (6 miles) — added stress to structures across West Java, where more than 1 million people experienced very strong tremors, according to the US Geological Survey (USGS).

Indonesian President Joko Widodo during his visit to the site on Tuesday promised to rebuild the damaged homes – more than 56,000 of them – to be earthquake-proof.

“The 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 have to be earthquake-proof.”

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

Indonesia, an archipelago country of more than 270 million people, lies along the Ring of Fire – a strip around the Pacific Ocean where most active volcanoes lie and most earthquakes occur when tectonic plates rub against each other, causing tremors.

Of the 310 people killed in Monday’s quake, at least 100 were children, many of whom were in school when the quake struck. a 6 year old boy They were 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 scraps of metal, timber and bricks. Most of the dead were crushed or trapped under rubble, said Ridwan Kamil, governor of West Java. Others were killed in landslides.

Cleo said very well when she heard about the earthquake, she tried to call her mother in Koginang, Cianjur, but when she failed to answer, she decided to drive there from her home in Bandung on a motorbike.

The journey—about 65 kilometers (40 miles)—usually takes less than two hours. But with roads completely blocked by landslides, it took 24 years.

“All the houses were covered in dirt and mud,” she added, adding that she had reunited with her family who had survived the earthquake.

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

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

They were considered sustainable homes, and largely durable in the event of an earthquake. However, increased deforestation and the rising cost of wood have led people to choose alternative materials, according to a 2009 study on post-disaster reconstruction in Indonesia from the Architectural Science Association.

More and more homes were being built of brick and concrete, the study said, and while the facade may have looked modern, the construction underneath was poor.

Furthermore, the low quality of concrete and poor steel reinforcement make these structures increasingly vulnerable to collapse during an earthquake – with maximum casualties caused by the weight of the materials, the report said.

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 that they sway and slide over the shaking ground instead of collapsing.

Architects have been developing this technology for decades, and engineers often adapt local materials and technologies in the area.

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

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

He said, “Our schools have not collapsed.” “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.

Many people in Nepal build their homes with clay mortar, Schildkamp said, which is very fragile. “If it is not fully reinforced, there is no additional stiffening in the building. That is what will collapse very easily.”

The Shieldcamp team used cement mortar and inserted horizontal stiffeners into the structure to strengthen it, rather than vertical ones.

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

We need knowledge and strategy in these countries. And we want governments to make these building codes mandatory.”

In West Java, hope is fading that more people will be pulled alive from the wreckage of the earthquake.

Aftershocks also complicate efforts, and residents now live in fear that the next disaster might topple their precarious homes again.

While President Widodo said the government would provide compensation of about $3,200 per head to owners of badly affected homes, many families in Cianjur lost everything. And now, they face the near impossible task of rebuilding.