<p>Numerous sources repeat that, apart from slowing down the rotation of the globe, the Three Gorges Dam caused the geographic pole to shift by 2 cm. For example:    <a href="https://blog.prv-engineering.co.uk/engineering-three-gorges-dam/" rel="nofollow noreferrer">https://blog.prv-engineering.co.uk/engineering-three-gorges-dam/</a>
&quot;The secret behind this phenomenon is called inertia and occurs as a result of Newton’s First Law Of Motion. According to NASA scientist, a shift in mass that size does affect the Earth. Raising 42 billion tons of water 180 meters above sea level increases the Earth’s moment of inertia which slows its rotation. It increases the length of a day by 0.06 microseconds while <strong>shifting the pole position by about 2 cm (0.8 inch)</strong>.
I'm curious, how did they calculated above mentioned &quot;2cm&quot;?,</p>

CC BY-SA 4.0
2021-02-05T05:16:17.063Z
The NASA source: https://www.jpl.nasa.gov/news/nasa-details-earthquake-effects-on-the-earth This seems to be based on this paper: https://www.semanticscholar.org/paper/Changes-in-the-Earth%27s-rotation-and-low-degree-by-Chao-Gross/68d5cca843020667d871eccc1e82a7aef075486d (click the academic.oup.com link).
Keith McClary
CC BY-SA 4.0
2020-12-29T04:32:48.463Z
"Raising 42 billion tons of water 180 meters above sea level increases the Earth’s moment of inertia which slows its rotation." The 180 meters is insignificant. You are taking a layer of water from the oceans and moving it to a certain latitude, which means a certain distance from the Earth's axis, which varies by thousands of km depending on the latitude. I did the math on the length-of-day change [here](https://earthscience.stackexchange.com/a/15946/6535).
Keith McClary
CC BY-SA 4.0
2021-01-27T04:46:07.533Z
Tectonic subsidence can counteract the raised water and changing sea level, so its only theory unless we have precise metrics of the planets geometry, which we don't afaik. Meanwhile a 315 billion-tonne iceberg breaks off Antarctica in 2019.
bandybabboon
CC BY-SA 4.0
2021-01-27T22:43:23.457Z
different but related: [Was the filling of the Three Gorges Dam's impact on the Earth's rotation rate detectable?](https://earthscience.stackexchange.com/q/9978/6031)
uhoh
<geophysics><water><earth-rotation><dams>
Did the Three Gorges Dam shift the North Pole by 2 cm?
Jacek Musial
# Did the Three Gorges Dam shift the North Pole by 2 cm?

(Asked by: username_0 on 2020-12-28)

Numerous sources repeat that, apart from slowing down the rotation of the globe, the Three Gorges Dam caused the geographic pole to shift by 2 cm. For example: <https://blog.prv-engineering.co.uk/engineering-three-gorges-dam/>
"The secret behind this phenomenon is called inertia and occurs as a result of Newton’s First Law Of Motion. According to NASA scientist, a shift in mass that size does affect the Earth. Raising 42 billion tons of water 180 meters above sea level increases the Earth’s moment of inertia which slows its rotation. It increases the length of a day by 0.06 microseconds while **shifting the pole position by about 2 cm (0.8 inch)**.
I'm curious, how did they calculated above mentioned "2cm"?,

**Tags:** geophysics, water, earth-rotation, dams

> **Comments:**
> **username_1**: "Raising 42 billion tons of water 180 meters above sea level increases the Earth’s moment of inertia which slows its rotation." The 180 meters is insignificant. You are taking a layer of water from the oceans and moving it to a certain latitude, which means a certain distance from the Earth's axis, which varies by thousands of km depending on the latitude. I did the math on the length-of-day change [here](https://earthscience.stackexchange.com/a/15946/6535).  
> **username_2**: Tectonic subsidence can counteract the raised water and changing sea level, so its only theory unless we have precise metrics of the planets geometry, which we don't afaik. Meanwhile a 315 billion-tonne iceberg breaks off Antarctica in 2019.  
> **username_3**: different but related: [Was the filling of the Three Gorges Dam's impact on the Earth's rotation rate detectable?](https://earthscience.stackexchange.com/q/9978/6031)  
> **username_1**: The NASA source: https://www.jpl.nasa.gov/news/nasa-details-earthquake-effects-on-the-earth This seems to be based on this paper: https://www.semanticscholar.org/paper/Changes-in-the-Earth%27s-rotation-and-low-degree-by-Chao-Gross/68d5cca843020667d871eccc1e82a7aef075486d (click the academic.oup.com link).  

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