Did an Earthquake Make Mount Everest Shorter? New Expedition Aims to Find Out
India and Nepal both plan to determine if the 2015 earthquake that devastated Nepal caused the world’s highest peak to lose an inch
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In April, 2015, a magnitude 7.8 earthquake devastated the Himalayan nation of Nepal—killing 9,000 and injuring thousands more. Soon after, data from Europe’s Sentinel-1A satellite indicated that the quake may have decreased the height of several mountains, including Mount Everest, the highest peak on Earth, by about an inch.
Now, Max Bearak at The Washington Post reports that India's surveyor general, Swarna Subba Rao, told reporters at the Geospatial World Forum in Hyderabad, India that his nation is planning to measure the mountain to confirm or refute those reports. “We are re-measuring it. It is almost two years since the major Nepal earthquake. After that, there is a doubt in the scientific community that it is shrinking,” Rao tells the Press Trust of India. "That is one of the reasons. Second reason is, it helps in scientific studies, plate movements etc.”
John Elliott, a geophysicist at the University of Leeds in England who has used the satellite data to try to measure changes in the mountains says he can’t say one way or the other whether Everest was affected. “What we've shown and others have corroborated is, it shrunk the highest mountains,” he tells Tia Ghose at Live Science. "But the lower mountains it built up a bit…because Everest is far away [from the epicenter], we can't conclusively say it went down; it's within the error of our measurement.”
Rao tells CNN he plans to send a team of 30 researchers on an expedition to the mountain this spring and that the team will measure the mountain using two procedures. “There are two methods. One is GPS. It is a survey instrument. It looks like a transistor. If you put it on the summit, say for ten minutes, it tells you the height. That is one,” he tells PTI. “The second is, ground method. Triangulation. We observe. The height can be calculated from ground.”
Though Rao says he is currently making the necessary diplomatic requests from Nepal for the expedition, Suresh Man Shrestha, deputy director general of Nepal's Survey Department tells CNN that India does not yet have permission to conduct a survey and Nepal is mounting its own effort to re-measure the mountain. "Nepal's survey department is working on a plan to survey Everest's height on our own—since there have been many claims about movement of its tectonic plate during the recent earthquake.” But, he adds that Indian scientists may be invited to join the Nepal led survey.
Whichever nation ends up spearheading the expedition, it will be historic. Obtaining accurate measurements of Mount Everest is more difficult and more disputed than one might think. According to Maseeh Rahman at The Guardian, when the mountain was first surveyed by George Everest in 1856, his trigonometric methods put the mountain at 29,002 feet. A 1955 expedition sponsored by India set the height at 29,029 feet. China’s state bureau of surveying put the height at 29,017 feet in 2005, though there was an ice cap that brought the spire to within seven centimeters of the Indian measurement. In 1999, an American expedition calculated the height at 29,035 feet including the cap of ice and snow.
To complicate matters, Ghose reports that the mountain may rise a quarter of an inch each year naturally due to stress between the Indian and Eurasian tectonic plates. That means natural growth of the mountain over the last 62 years might mask any small shrinkage caused by the earthquake. “We don’t know how much of that ‘up’ eventually must come back down in these earthquakes," explains Elliott, saying measuring any change from the quake will be difficult but not impossible to detect.