Why Are There So Many Landslides in Indonesia This Year?

The rainy season is also landslide season in Indonesia. Late last week, four people were killed when a landslide buried homes, toppled trees, and overturned cars in Banaran village, in Ponorogo, East Java. The landslide stretched for more than 1.5 kilometers, burying everything in its path under a 20-meter-high wall of muddy earth. Search and rescue teams believe that as many as 38 people could still be buried beneath the landslide. But continued rains, and concerns over additional landslides, have hampered search and rescue efforts.

Saturday's landslide was just the latest in a particularly deadly rainy season. In March, a landslide damaged or destroyed more than 100 homes in Banjarnegara district, Central Java. In central Bali's Bangli district, a dozen people were buried alive in a landslide caused by flash floods in Songan village. The youngest victim was a 1-year-old boy.

By the start of this month, there were already 251 landslides reported throughout Indonesia, according to the National Disaster Mitigation Agency (BNPB). It's a deadly start to 2017, and a grim sign of what's to come. Last year, the BNPB recorded 612 landslides in Indonesia—the highest number in more than a decade. The BNPB is warning people living in landslide-prone areas to remain vigilant over the possibility of disaster.

So what's going on? Why are so many landslides occurring recently? The answer is a complicated mix of issues stemming from climate change, environmental destruction, shoddy infrastructure, and poverty, according to experts.

There are more than 40 million people living in landslide-prone areas—or about 17 percent of Indonesia's population. Few live in villages with adequate emergency warning systems. The BNPB estimates that there are only about 200 landslide warning systems nationwide, a fraction of the more than 100,000 the country likely needs, BNPB spokesperson Sutopo Purwo Nugroho told local media.

How can so many people live in dangerous areas? It has a lot to do with Indonesia's soil. The country is famously on the ring of fire, a belt of highly-volcanic islands that stretches for more than 40,000 kilometers across the Pacific Ocean. The volcanos created wonderfully fertile soil—a key component of nation's history as an agrarian society and a driver of population growth and settlement patterns in Indonesia. To put it simply, farming villages sprout where there is fertile soil, and in a place like Java—the world's most densely populated island—villages can grow into towns and small cities over time.

But this same soil also makes Indonesia a dangerous place to live. The Ministry of Agriculture estimated that as much as 45 percent of all soil in Indonesia is prone to landslides.

"Indonesian soil is very fertile because it sits by the ring of fire, but that also means we're vulnerable to geological disasters," said Ngadisih, a researcher with the Center For Disaster Management at Yogyakarta's Gadjah Mada University. "The fertile soil causes a rise in population, but the soil itself is susceptible to mass shifting."

But it's always been this way. Why are there so many landslides now? The fault lies in the weather and an increase in development. Indonesia was stricken with serious droughts last year thanks to the weather phenomenon El Niño. The droughts destabilized the soil and increased the risk of landslides, Ngadisih explained.

Then this year, El Niño's sister La Niña caused the opposite, drenching Indonesia in torrential rain. Together, the two weather phenomenons wrecked havoc on the nation's soil.

"Water evaporation that happens during a long draught causes cracks," Ngadisih said. "During rainy season, the soil is saturated with water and those cracks can cause landslides."

Increased development only compounds the problem. New roads run along the edge of mountains, where the vibrations of passing trucks shake the soil loose. Even looser regulations mean that people build homes and cultivate farms in areas that were never safe for habitation.

"Landslides are natural because nature needs balance, but there has to be land regulations so we can keep casualties low," Ngadisih said.

National law prohibits the construction of terraced farming on slopes greater than 50 degrees, Ngadisih explained. But enforcement is weak and in many places, like Banaran village, hills with dangerously steep slopes are converted to terraced farms.

The entire village was built on a steep slope atop a layer of weathered volcanic rock, said Bagus Bestari Kamarullah, the spokesman for the UGM quick response team.

"The land use is alarming because there are farms that shouldn't be on slopes like these," Bagus said. "Whether there is high rainfall like in the past couple of days or not."

Similar issues are playing out across South America, where a series of landslides have left hundreds dead in natural disasters caused by changing weather patterns and ongoing issues with deforestation and unchecked development.

But a rise in landslides doesn't necessarily mean that a country has to suffer higher death tolls. Indonesia can save lives by raising awareness of the dangers of landslides, Ngadisih said.

"There are a lot of high-risk zones that turned into residential areas," she explained. "We should educate people so they would know what to do during a natural disaster and what the evacuation process is. We should train them so they're aware of their environment and are able to detect the early signs of a disaster."