WHAT if an earthquake could do more than rattle buildings — what if it could change the length of a day?
Some researchers believe they could even affect the Earth’s rotation.
Could something happening miles below us change how long a day is on Earth?
VERDICT:
TRUE
In March 2011, a 9.0 magnitude earthquake in Japan caused a surprising shift in Earth's rotation, but not in the way many might expect.
While it didn’t disrupt Earth’s North-South axis, around which the planet rotates, it did move what’s called the “figure axis” by about 33 feet (10 metres). The figure axis is an imaginary line that balances Earth’s mass, and any shift in it slightly affects the planet’s spin.
The earthquake caused the planet to spin slightly faster, shortening the length of a day on Earth by 1.8 microseconds—about one-millionth of a second.
Scientists are more interested in how the earthquake affected Earth’s wobble, as it provides valuable data for future space missions and could help improve earthquake prediction.
Using high-precision GPS data, researchers discovered that parts of Japan shifted by as much as 13 feet (4 metres) due to the quake’s fault plates moving.
This allowed scientists to calculate how the earthquake redistributed Earth’s mass, which in turn affected its wobble.
A useful comparison is to think of a figure skater who pulls her arms in while spinning, which causes her to spin faster.
Similarly, when mass shifts closer to the equator during an earthquake, Earth’s spin accelerates.
This isn’t the first time a major earthquake has changed the length of Earth’s day.
Previous quakes, like the 8.8-magnitude earthquake in Chile (2010) and the 9.1-magnitude Sumatra quake (2004), also shortened the day.
Even though these tiny changes don’t affect our daily lives, it is definitely an interesting fact that not many might be aware of.
REFERENCES
https://www.space.com/11115-
https://www.jpl.nasa.gov/news/
