Chile quake shortened our day, NASA says

March 3rd, 2010 - 3:40 am ICT by BNO News  

By Michael van Poppel
The Earth SANTIAGO, CHILE (BNO NEWS) — The massive 8.8-magnitude earthquake that struck south-central Chile on early Saturday was so powerful that it affected Earth’s rotation, shortened the length of day, slightly changed the planet’s shape, and shifted the North Pole, NASA said on Tuesday.

The space agency used a computer model at the Jet Propulsion Laboratory in Pasadena, California to study the effects of the earthquake, which was one of the most powerful earthquakes in modern history.

However, the changes are not that unusual, according to NASA scientists who say that all earthquakes have some affect to the Earth’s rotation, although they are usually barely noticeable. “Any worldly event that involves the movement of mass affects the Earth’s rotation, from seasonal weather down to driving a car,” said Dr. Benjamin Fong Chao, of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

According to the study, Saturday’s earthquake found the Earth’s figure axis - the North Pole - to have shifted by some 8 centimeters, meaning each day is now about 1.26 microseconds shorter.

A similar change happened on December 26, 2004 when a 9.3-magnitude earthquake rocked the west coast of Sumatra, Indonesia, unleashing a devastating tsunami that killed hundreds of thousands of people across Asia.

That earthquake, which was much stronger than Saturday’s earthquake, shortened the length of day by 2.68 microseconds. Physically that is like a spinning skater drawing arms closer to the body resulting in a faster spin. The 2004 earthquake also affected the Earth’s shape. A NASA study found Earth’s oblateness (flattening on the top and bulging at the equator) shortened by one part in 10 billion, continuing the trend of earthquakes making the Earth less oblate.

Saturday’s earthquake in Chile killed at least 795 people and injured hundreds more. The earthquake, one of the strongest recorded, happened only weeks after one of the most deadliest earthquakes in modern history - the 7.0-magnitude earthquake that killed more than 230.000 people there.

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