in March 2011 A 9.0 magnitude earthquake hit the east coast of Japan followed by a powerful tsunami. caused the death of approximately 20,000 people and the accident at the Fukushima nuclear power plant. However, this natural disaster it also changed the earth’s axis and even shortened the length of the days.. The strongest earthquake ever recorded in a country with a long history in this regard shifted the planet’s axis by about 17 centimeters and may have shifted the main island of the Japanese archipelago by about 2.4 meters.
But in addition to that, as with other earthquakes of similar magnitude, the planet’s rotation speed has changed: “Earthquakes can change the Earth’s rotation by rearranging the planet’s mass. This is what an ice skater does to spin faster: He moves his arms closer to his body, bringing his mass closer to the axis around which it rotates. Earthquakes do the same,” Richard Gross of NASA’s Jet Propulsion Laboratory told Popular Mechanics in 2011.
“This earthquake To make the Earth spin faster and the day length slightly shorter, it should have moved the mass a little closer, on average, to the Earth’s axis of rotation.‘ he pointed.
By looking at the mass distribution patterns of the Earth before the earthquake and analyzing how the fault shifted during the earthquake, Gross was able to understand how the mass distribution changed.
“If we know how the mass of the Earth is rearranged through conservation of angular momentum, then we also know how the rotation of the planet changes,” he added.
In total, the earthquake Speeded up Earth’s rotation by about 1.8 microseconds (1.8 millionths of a second). The 2004 Indonesian earthquake, by comparison, sped up Earth’s day by about 2.68 microseconds.
However, earthquakes are not the only events and factors that affect the speed of Earth’s rotation. Benjamin Fong Chao of NASA’s Goddard Space Flight Center, after the 2004 Indonesia earthquake, said, “Any mundane event involving mass motion affects the Earth’s rotation, from seasonal weather to driving a car.”
The Moon recedes and the Earth slows
There are all kinds of factors that affect the rate of rotation, such as changes in sea level as well as changes within the Earth. The most important factor is that the Moon is moving away from the Earth.. The result is Earth slowing down, albeit with some bursts of speed from time to time.
Scientists studying ancient corals discovered that the Earth rotated much faster 444-419 million years ago. As the coral grows, it leaves a thin layer of calcium every day. Because corals grow more in the dry season than in the wet season, you can count the calcium carbonate deposits in each season and calculate how many days are in a year. Using this method, the team discovered that: Earth lived 420 days a year 444-419 million years ago.Before it slowed down under the influence of our Moon.
Reference article: https://www.popularmechanics.com/science/environment/a6543/how-the-japan-earthquake-made-the-day-shorter/
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