[I have wondered…"As the world turns."]

NASA Confirms China’s Three Gorges Dam Has Slowed Earth’s Daily Rotation

Mass Redistribution and Earth’s Spin

The effect is linked to the dam’s vast reservoir on the Yangtze River. By concentrating water in one region, the structure redistributes mass across the globe. This changes Earth’s moment of inertia, the same principle that governs how a figure skater spins faster or slower by moving their arms. The result is a subtle but detectable delay in rotation.

NASA calculations show the impact is tiny compared to natural events, but significant in illustrating the scale of human engineering. By comparison, the 2004 Sumatran earthquake shifted enough mass to shorten the length of a day by 2.68 microseconds.

The Three Gorges Dam is the largest of its kind, but it is not the only example of infrastructure altering geophysics. Research published in Geophysical Research Letters suggests the cumulative effect of thousands of dams worldwide has nudged Earth’s rotational axis by nearly a meter over recent decades. Similar measurements have also linked large seismic events to changes in spin and tilt.

https://orbitaltoday.com/2025/09/03/nasa-confirms-chinas-three-gorges-dam-has-slowed-earths-daily-rotation/