A massive experiment in Taiwan aims to reveal landslides’ surprising effect on the climate

American Association for the Advancement of Science (AAAS)
Date: Nov. 20, 2019
By: Katherine Kornei

Steep, wet slopes and earthquakes make landslides a common feature in Taiwan’s Taroko National Park. KRISTEN L. COOK

TAROKO NATIONAL PARK, TAIWAN—The frequent crackle of tumbling rocks overhead is unnerving, especially when you're picking your way through a pile of jagged debris. "I hate walking down roads like this," says Niels Hovius, a geomorphologist at the GFZ German Research Centre for Geosciences in Potsdam. "I know what can happen here."

Taroko National Park, famous for a precipitous marble gorge that cuts through it, is in a futile fight with gravity. Rockfalls litter the park's serpentine main highway. The scars of at least a dozen landslides punctuate the view in all directions. Maintenance crews are perpetually spraying concrete on slopes in a last-ditch effort to stabilize them. The park gives out safety helmets for free, and strongly encourages visitors to wear them.

For Hovius, all this moving rock and soil makes for a perfect laboratory. For the past 3 years, he and his colleagues have scrambled and rappelled across the park, installing dozens of instruments in what will end up being Taiwan's most comprehensive landscape dynamics observatory. One goal is to monitor landslides and understand their triggers. A bigger aim is to investigate their hidden impact on the climate: As massive chemical reactors, landslides draw carbon dioxide (CO2) out of the sky and sometimes belch it out, too. Understanding their role as both carbon source and sink could help researchers better model the carbon cycle that ultimately controls our planet's climate and habitability.

The recipe for landslides requires three basic ingredients: steep hillslopes, earthquakes to weaken them, and water to make them slick. Taiwan has all three in spades, making it one of the most landslide-prone countries in the world. The island was born 6 million years ago in an ongoing collision of tectonic plates that lifts mountains and generates a drumbeat of earthquakes. And its location in the tropical western Pacific Ocean means typhoons come regularly, occasionally dumping meters of rain in just days. "You can learn a lot by looking at extremes," says Susan Brantley, a geochemist at Pennsylvania State University in State College.    [FULL  STORY]

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