25-cm shift in Earth’s axis has little effect, experts say

Initial results out of Italy’s National Institute of Geophysics and Volcanology show that the 8.9-magnitude earthquake that rattled Japan yesterday shifted Earth’s rotation axis by about 25 centimetres.
INGV’s report, which came hours after the devastating quake, is equivalent to “very, very tiny” changes that won’t be seen for centuries, Canadian geologists say.
Only after centuries would a second be lost as each day is shortened by a millionth of a second, according to University of Toronto geology professor Andrew Miall.
“Ten inches sounds like quite a lot when you hold a ruler in front of you. But if you think of it in terms of the earth as a whole, it’s absolutely tiny; it’s minute,” he said.
“It’s going to make minute changes to the length of a day. It could make very, very tiny changes to the tilt of the Earth, which affects the seasons, but these effects are so small, it’d take very precise satellite navigation to pick it up.”
Earth’s rotation will now shift at a different speed because the globe’s mass has been redistributed, said Michael Bostock, a University of B.C. earthquake seismology professor.
He used an analogy of a figure skater pulling in his or her arms to spin faster because weight has been reorganized.
“Ultimately, if you change the length of day, you can change the length of time a given point on Earth receives sunlight and doesn’t receive sunlight,” he said. “But will this affect us in our lifetimes? Absolutely not.”
The researchers said that although the minuscule change may be undetectable, it still illustrates the punch behind Japan’s earthquake.
Last year, NASA reported that an 8.8-magnitude earthquake that hit Chile shortened the day by 1.26 millionths of a second, according to computer-model calculations.
NASA had estimated that the Chilean earthquake shifted the globe’s axis by about 10 centimetres, National Geographic reported at the time.
INGV, Europe‘s largest research institute to monitor geophysics, said the impact of yesterday’s event was “much greater” than 2004′s Sumatra earthquake, which clocked in at a magnitude of 9.1.