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The Nepal Earthquake Made Mt. Everest an Inch Shorter

Satellite data gives the first results for the way the land moved during the quake

Sentinel-1 image showing the effects of the April 25 earthquake in Nepal (ESA/Copernicus data 2015)
smithsonian.com

Millions of people are struggling to cope with displacement and devastation following the deadly Nepal earthquake that claimed over 6,000 lives, though that count is expected to rise as rescue efforts move into more remote areas. In the background, scientists are working to understand exactly what happened during the 7.8-magnitude quake. Becky Oskin reports for Livescience that many are turning to satellite data, that reveals a region 75 miles long by 30 miles wide lifted up by as much as three feet. 

Although the earthquake’s epicenter was 48 miles from the capitol, the uplift’s peak is only 10 miles away from Kathmandu. "That's one of the reasons why Kathmandu has so much damage," geophysicist Tim Wright of the University of Leeds told Oskin. The changes the earthquake wrought on the landscape are visible to the eyes of Europe’s Sentinel-1A radar satellite. Oskin writes:

Researchers detected the vertical shift in the ground by comparing before-and-after radar images from the satellite using a technique that produces an image called an interferogram. The resulting images have rainbow-colored areas that represent the movement of the ground between the times each radar image was taken. Each colorful fringe on the European Space Agency's Nepal interferogram reflects about 1 inch (2.8 centimeters) of vertical movement. The results will be refined in the coming weeks, with as scientists further analyze the images and additional data from satellites become available.

The approximately 20-second-long earthquake and continuing aftershocks have their origins in the action of the Indian tectonic plate sliding under the Eurasian plate. It’s the same process that has pushed the Himalayas up to their impressive heights. The April 25 quake was relatively shallow, reports Joel Achenbach for The Sydney Morning Herald

While the region around Kathmandu lifted up, Mount Everest and other tall peaks in the area dropped down by about one inch, Oskin reports. 

The small decrease will soon be overtaken by the range’s continued growth, however. The Himalayas are lifting up at a rate of about 0.4 inches every year. So the tallest mountain’s height loss isn’t permanent. Unfortunately, Nepal will likely need more time and help to recover from the loss of life and cultural treasures taken by the earthquake.

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