Japanese earthquake reduced the length of a day on Earth


15/03/2011

The huge earthquake that struck northeastern Japan, reduced the duration of the earth of the day was the reason for the changes in the position and rotation of the globe.

As a result of the new research geophysicist Richard Gross of NASA’s Laboratory in California, it was found that the intense earthquake of magnitude 8, 9 points sped up the Earth’s rotation, shortening the length of the 24-hour day by 1.8 microseconds. Gross re-estimated the effects of the earthquake, as they had previously proposed the reduction of the day by 1.6 microseconds, and based its approval on the new data, highlighting how much the fault that triggered the earthquake, contributed to a redistribution of planetary mass. Microsecond - a millionth of a second.

The actions associated with the Earth’s rotation are similar to the actions of a skater, which adds up and presses her hands close to your body while rotating in the air to quickly get back on the ice. The closer the mass shift during an earthquake to the equator, the more it speeds up the rotation of the Earth.

One Earth day is about 24 hours, or 86,400 seconds. Throughout the year, the length varies by about one millisecond, or 1,000 microseconds, due to seasonal changes in the distribution of planetary mass, for example, the seasonal shift of the jet stream.

The initial data of the Center of Geological Research in the U.S. shows that the earthquake shifted the main island of Japan by 8 feet (2.45 meters). Earthquake Observation scientists also caused the displacement of the outer Earth’s axis by about 6 1/2 inches (17 centimeters). External earth’s axis is not the same as the north-south axis in space which rotates every day at about 1,000 miles per hour (1604 km).

This is not the first time that a huge earthquake affects the length of the Earth day. Large earthquake shortened the length of the day and in the past. Thus, the magnitude 8.8-magnitude earthquake last year in Chile also accelerated the planetary rotation and shortened the day by 1.26 microseconds. Earthquake on the island of Sumatra in 2004 decreased by 6.8 microseconds day.

Japanese earthquake magnitude 8.9-magnitude reduction process of the day on Earth may not be over. The weaker aftershocks may also contribute to small changes in day length.

The earthquake that occurred on March 11, was the most formidable of all ever recorded in Japan and the fifth largest earthquake in the world since 1900, according to information USGS. It struck the coast, located about 231 miles (373 kilometers) northeast of Tokyo and 80 miles (130 kilometers) east of the city of Sendai and caused a huge tsunami that devastated the northeast coast of Japan. At least 20 subsequent aftershocks recorded value of 6 points or more have followed the main earthquake.

"In theory, anything that redistributes the Earth’s mass, the rotation changes the Earth" - said geophysicist Gross. "So basically small tremors also affects the rotation of the Earth. But while the tremors are small, and their influence is too small."

Original: LiveScience Translation: M. Potter


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