Space.com
3/2/2010
The massive 8.8 earthquake that struck Chile may have changed the entire Earth’s rotation and shortened the length of days on our planet, a NASA scientist said Monday.
The quake, the seventh strongest earthquake in recorded history, hit Chile Saturday and should have shortened the length of an Earth day by 1.26 milliseconds, according to research scientist Richard Gross at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“Perhaps more impressive is how much the quake shifted Earth’s axis,” NASA officials said in a Monday update.
The computer model used by Gross and his colleagues to determine the effects of the Chile earthquake effect also found that it should have moved Earth’s figure axis by about 3 inches (8 cm or 27 milliarcseconds).
The Earth’s figure axis is not the same as its north-south axis, which it spins around once every day at a speed of about 1,000 mph (1,604 kph).
The figure axis is the axis around which the Earth’s mass is balanced. It is offset from the Earth’s north-south axis by about 33 feet (10 meters).
Strong earthquakes have altered Earth’s days and its axis in the past. The 9.1 Sumatran earthquake in 2004, which set off a deadly tsunami, should have shortened Earth’s days by 6.8 microseconds and shifted its axis by about 2.76 inches (7 cm, or 2.32 milliarcseconds).
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