The Himalaya ‘breathes’, growing and shrinking in cycles

May 13, 2021

If we could put our planetary clock on fast forward, Earth’s surface would writhe with activity. Continents would scurry across the globe, oceans would open and close, and new mountains would shoot up toward the sky.

Yet even as mountains rise, they also periodically sink back down when the stress from tectonic collisions triggers earthquakes. These events happen in a cycle, like the chest of a rocky behemoth drawing uneven breaths, explains Luca Dal Zilio, a geophysicist at the California Institute of Technology.

In a new paper published in Nature Reviews, Dal Zilio and his colleagues have stitched together results from more than 200 past studies of Himalayan geology to lay out the intricate mechanisms behind these geologic respirations—as well as the many challenges that remain.

Since similar geologic “breaths” have been documented around the world, the new work is key to grasping the processes that sculpt many of Earth’s mountain ranges—and figuring out the risks those ranges might also pose. The Himalaya’s lengthy expanse and geologic complexity make it a terrific natural laboratory, says study co-author Judith Hubbard, a structural geologist at Nanyang Technological University in Singapore.

Different zones in a string of mountains may produce different types or intensities of exhalations. While some violently cough, others might generate a series of hiccups, Hubbard says. And just because a section of mountains exhaled one way at one time doesn’t mean it’ll do so again.

“Even the same patch can have different behaviors at different times,” says Rebecca Bendick, a geophysicist at the University of Montana who was not involved in the new paper. “And pretty much nobody has the foggiest clue why.”

Source:https://www.nationalgeographic.com/science/article/himalaya-breathes-with-mountains-growing-and-shrinking-in-cycles