The world's largest hydroelectric dam in China called the Three Gorges Dam is a very huge infrastructure project that is affecting the spin of Earth, according to IFL Science. The dam, located in central China’s Hubei province, is spread across the longest river in Eurasia, the Yangtze River. It uses the flow of water from three nearby gorges – Qutangxia, Wuxia, and Xilingxia – to spin turbines and generate electricity. The dam was first found to have Earth-shifting capabilities in 2005 when US space agency NASA discovered how the rotation of our planet was affected by the 2004 catastrophic Indian Ocean earthquake and tsunami.
In its blog, NASA explained how changing the distribution of mass on Earth can have a very small influence on the planet's moment of inertia. Similarly, the spin of Earth can be impacted following an earthquake due to the motion of the tectonic plates, the space agency said.
According to NASA, this is what happened in 2004 after the earthquake in the Indian Ocean. The scientists found that the mass distribution on Earth was altered by the earthquake and the length of a day was decreased by 2.68 microseconds.
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Experts explained that a massive shift of water can also change the spin of Earth. According to IFL Science, in a 2005 post, Dr Benjamin Fong Chao, a geophysicist at NASA’s Goddard Space Flight Center, explained that the giant Chinese dam is able to hold 40 cubic kilometres (10 trillion gallons) of water. By his calculation, this shift of mass would increase the length of a day by 0.06 microseconds and move the pole position of Earth by about 2 centimetres.
It's not much, even compared to the marginal effect of giant earthquakes, but it's fairly significant for a human-made structure, the outlet said.
Further, it noted that humans are influencing the rotation of our planet in other ways too. It said that a similar effect is currently being caused by climate change and its impact on Earth's mass distribution. With the increase in temperatures and melting of polar ice caps as well as the rising of tropical seas, more mass has gathered at the equator of the planet in comparison to its poles. This is slowing the spin of Earth and leading to slightly longer days.
