Himalayan Range “Drops” After Massive Quake

Mt. Everest

Photo courtesy of NASA

Himalayan Range “Drops” After Massive Quake
| published May 9, 2015 |

By Keith H. Roberts Thursday Review contributor

The complex debate about the exact height of the world’s tallest mountain just got more complicated, and confusing.

The powerful April 25 earthquake which devastated Nepal and cost the lives of thousands has also substantially shifted the height of much of the Himalayan mountain range, and may have altered the height of Mount Everest—on the border between Nepal and China—by as much as three feet.

Satellite imagery and data, coupled with other geological data, indicate that some parts of the Himalayan range—the area known as the Langtang Himal, or Langtang Range, dropped in relative height by about three feet. Though Everest’s position and height has not yet been officially measured, scientists believe it too may have lost some of its impressive height—perhaps by as little as a few inches, or perhaps by as much as several feet.

The U.S. Geological Survey says that a vast stretch of at least 80-to-100 kilometers of mountains have been affected by the 7.8 magnitude quake, as parts of one of the Earth’s plates shifted under another plate. Areas south of the range shifted violently upward, while some areas north of the where the two plates overlap may have been pushed down. Nepal’s capital city of Kathmandu is located near the southern edge of the disrupted zone, where the ground was shoved upward by the movement of the two plates. The areas south of Kathmandu are being pushed downward by the force of the movement, which is where the Eurasian tectonic plate smashes against the Indian tectonic plate.

The earthquake was felt for thousands of square miles, and in addition to the massive damage it inflicted on cities, towns and villages all across Nepal, the quake triggered landslides, and triggered avalanches which killed or injured many hundreds of hikers, campers and mountain climbers. Scores of climbers and hikers are still unaccounted for in the mountainous areas. In all, the death toll has climbed past 7900 in Nepal.

Satellite imagery from a variety of scientific sources—U.S., German, Chinese, and others—indicates that the drop in height in the Langtang region is relatively widespread, and consistent. Further studies and additional data will be needed to offer definitive measures of the vertical changes.

Most experts agree that Mount Everest, the world’s tallest peak, is 29,029 feet in height. But that height came after decades of disagreement by several of the countries closest to the famous mountain. Nepal and India had always relied on the figure of 29,029, but Everest’s neighbor on its northern face—China—officially listed Everest’s height as 29,016. Part of the dispute was over whether to measure the mountain’s height by the actual rock surface at the peak, or whether to measure it based upon the substantial, mostly permanent snowcap, which adds the additional 13 feet. Indian surveys in 1955 concurred that it was appropriate to measure Everest to the top of its snowcap, since the snow never melted nor shifted in height.

In 1999, a team of American and British geologists used GPS technology to settle on a height of 29,030—give or take and inch—which was the figure adopted by the National Geographic Society shortly afterwards.

Then, after much discussion and scientific debate, all sides agreed to the uniform figure of 29,029 in 2010. Geologists, however, say that Everest’s height will always been subject to change, since it sits atop a mountain range along the confluence of those two enormous tectonic plates.

Related Thursday Review articles:

Australia, Seen From Space; Thursday Review staff; Thursday Review; April 8, 2015.