Quake shifted island, sped up Earth's rotation

March 12, 2011

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12/03/2011 1:41:12 PM

CTV.ca News Staff

The changes may be imperceptible to most people, but the massive earthquake that

struck off the coast of Japan Friday had a startling impact on the Earth,

experts say. The 8.9-magnitude quake moved Japan's main island by more than two

metres, in addition to shifting Earth on its axis and briefly speeding up its

rotation.

Early data from Japan suggests the earthquake moved the island about 2.4 metres,

according to Hudnut of the U.S. Geological Survey. The agency compared

information from a GPS station that had moved by more than two metres with

satellite images from Japan.

Late Friday, scientists at NASA revealed the quake shaved more than a

microsecond from the day. The quake, which lasted about two minutes, sped up the

earth's rotation by about 1.6 microseconds. (One microsecond is one-millionth of

a second.) NASA geophysicist Gross said the quake shifted the Earth's

mass, which caused the change in speed.

While the speed change was only slightly more than what was caused by last

year's earthquake in Chile, it was considerably less than the quake in Sumatra

in 2004. That quake sped up the Earth's rotation by 6.8 microseconds.

Meanwhile, a report from Italy's National Institute of Geophysics and

Volcanology suggested Friday's quake shifted the Earth on its axis by an

estimated 10 centimetres.

The quake was the fifth-largest recorded in the world since 1900. The quake was

an estimated 299 kilometres long and 150 kilometres wide, and occurred where the

North American and Pacific tectonic plates intersect, in the northwest region of

the " Ring of Fire. "

Thousands of people were missing after Friday's tremblor, which triggered a

tsunami that swept away entire villages. By late Saturday, the death toll had

risen to more than 600, with thousands of people still missing. Several million

residents were also without power.

With files from The Associated Press

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