Preliminary results of an ongoing survey, obtained by THT, show the new height of Mt Everest to be approximately 8,848.9 metres in World Height System, which is 90 cm more than the current official value of Nepal. The margin of error is about 10 cm. The final results of the survey, being jointly undertaken by the National Space Institute (DTU) of Denmark and the Department of Survey, Nepal are yet to be calculated. The geoid of Nepal was measured through an airborne gravity survey in December last year.
Earlier, a survey team led by Y Chen of China in 2005 had put the snow height at 8,847.93 metres whereas the National Geographic Society survey of 1999 had pegged the height at 8,850 metres, some seven feet higher than previously thought. Scientists used Global Positioning System satellite equipment carried to the summit by two Sherpas on May 5 of that year to calculate the height.
The Himalayas are the most rugged gravity field on the planet, and one of the goals of the 2010 airborne survey, which was done at a height of about 35,000 feet, was to find a revised height of Mt Everest, said researchers from DTU and DoS. The Nepal government is, however, trying to measure the height of the world’s highest mountain on its own. The government announced in July that it was measuring the height of the world’s tallest mountain using latest technology.
“Currently the proposal is at the Ministry of Finance for programme approval,” Krishna Raj BC, Director General of DoS, said. “We are looking at more beneficial options and are corresponding with different international agencies. We still need a lot of assistance to move this project ahead.” GPS measurements of Everest, particularly by Chinese and Italian teams were done in 1995, 1999 and 2005. Earlier technology used methods of levelling and triangulation from the sea level, including sea level in Kolkata and the Yellow Sea.
The airborne gravity survey was done by Rene Forsberg, Arne V Olesen and Indridi Einarsson from DTU and Niraj Manandhar and Kalyan Shrestha from DoS, Nepal.
The government entered into an agreement with DTU in 2009. Scientists think Everest is growing taller by about 4 mm every year due to uplift caused by the Indian tectonic plate pushing northward into Asia.AJAYA BHADRA KHANAL, THT