Is the North Pole shifting towards Japan?
earthquakes round the world are dragging the North Pole towards Japan. It has been discovered by Giorgio Spada of the University of Bologna, Italy, that the largest of the quakes, most of which occur along the Pacific rim, tend to tilt the pole towards their epicentres.
This finding is a continuation of a study last year by Benjamin Chao of the National Aeronautics and Space Administration's Goddard Space Flight Center in Maryland, us . Chao and his colleagues looked at the records of earthquakes since 1977 in order to figure out how earthquakes had affected the earth's rotation. Earthquakes occur due to the shifting of the earth's crust and the mantle underneath. These might result in distortion of the earth's shape and can also change its axis of rotation and speed, just as spinning ice-skaters turn faster or slower by moving their arms in or out ( New Scientist , Vol 153, No 2074).
According to Chao's team, earthquakes since 1977 have slightly pushed the North Pole towards Japan at the rate of about six centimetres each century. However, they could not point out why the shift is always towards Japan. Chao suggested that there is perhaps some link between the earth's rotation and the earthquakes.
Spada was keen to probe this mysterious link. He studied the effect of individual earthquakes and figured out that during large quakes, one plate of the earth's crust slides under another resulting in redistribution of mass. According to Spada's calculations, the mass rearrangement is most likely to pull the North Pole along the longitude containing the epicentre of the quake. And since most of the large earthquakes occur round the Pacific rim, this explains the slight polar motion towards Japan.
Chao hopes to confirm Spada's theory by watching the effect of a single, huge earthquake. In case of an earthquake of magnitude 8.5 on the Richter scale, the pole is likely to shift by a few millimetres; this can be measured by state-of-the-art astronomical detectors.
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