12 years ago, there was an earthquake that deflected the Earth's axis

In March 2011, a magnitude 9 earthquake struck off the east coast of Japan, shifting the Earth’s axis and shortening the time of day.

The strongest earthquake in Japanese history shifted the Earth’s axis by about 17cm and could cause the main island to shift about 2.4m . Like other similar large earthquakes, it also changes the Earth’s rotation speed, IFL Science reported on March 9.

12 years ago, there was an earthquake that deflected the Earth's axis
Earth’s rotation axis changed after the 2011 earthquake in Japan. (Photo: Jim Barber).

“Earthquakes can change Earth’s rotation through planetary mass rearrangement, similar to how a skater spins to make herself spin faster. She would put her hands close to her body to make her spin faster. mass shifts closer to the axis of rotation,” explains Dr. Richard Gross of NASA’s Jet Propulsion Laboratory. “Earthquakes have a similar effect. This quake certainly moves the average mass closer to the Earth’s axis of rotation , causing the Earth to rotate faster and the day a bit shorter.”

By looking at a model of the Earth’s mass distribution before earthquakes and using estimates of how faults slip during earthquakes, Gross was able to calculate how the mass distribution changes. Then, based on the law of conservation of angular momentum, if the researcher knows how the Earth’s mass is rearranged, the researcher can know how the Earth’s rotation changes.

The earthquake off the coast of Japan caused the Earth to rotate about 1.8 microseconds faster. For comparison, the 2004 earthquake in Indonesia shortened the day on Earth by an estimated 2.68 microseconds. Earthquakes aren’t the only events that affect the Earth’s rotational speed. According to Dr. Benjamin Fong Chao of NASA’s Goddard Space Flight Center, any event that shifts mass has an impact on Earth’s rotation, ranging from seasonal weather, sea level changes and shifts in space. underground, in which the largest element is the Moon

Through looking at ancient coral specimens, scientists speculate that the Earth once rotated faster 444 – 419 million years ago . Each day, corals gain a new layer of calcium as they grow. Because corals thrive more in the dry season than in the wet season, researchers were able to count the number of calcium carbonate rings in each season and calculate how many days there are in a year. Using this method, the researchers calculated that Earth had 420 days between 444 and 419 million years ago before slowing down under the influence of the Moon.