Losing ground

To tectonics

 
Published: Saturday 30 April 2005

-- What do clothes and countries have in common other than the fact that both start with the same letter? Both can shrink, according to a US seismologist.

Roger Bilham of the Colorado University in the US says Nepal is shrinking by 18 millimetre (mm) each year as a result of the Indian tectonic plate pushing against the Asian plate. "This is equivalent to the loss of two soccer fields a year along its 600 kilometre-long northern border (with Tibet)," he remarks in a report based on global positioning system (commonly referred to as GPS) measurements.

The readings show Nepal is getting shortened because the Indian plate is moving 50 mm closer to Asia every year, or about one mm each week. At the same time, Tibet moves 32 mm closer to Asia each year.

Such movements of tectonic plates can cause earthquakes in the Himalayan region. "Several earthquakes measuring more than 8 magnitude (on the Richter scale) may be overdue," says Bilham. But little can be said about when they might strike.

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