October 27, 2011 11:45
French scientists have proposed a new unexpected hypothesis to explain the shift of the magnetic poles of the Earth. They believe that this change is associated with the movement of tectonic plates.
The magnetic poles of the Earth, in contrast to the geographical (South and North Pole), do not have permanent origin, and move slowly. It is believed that this drift is due to the large amount of iron in Earth's core. Most of the iron is in the molten state and uneven running. Because of this, the magnetic field created by iron impermanent. For example, at the beginning of XXI century, the north magnetic pole was located off the coast of Ellesmere Island, and is now moving toward Siberia. Paleomagnetic dating showed that about 780,000 years ago, there was a complete reversal when the magnetic north pole moved south. Inversion occurred before that time, in a similar shift of the poles usually takes about a thousand years.
A new hypothesis
A team of scientists led by Dr. Francois Petrella (F. Petrelis) from the University of Earth Physics (Paris) has proposed a new original hypothesis to explain the drift of the magnetic poles. According to the authors, the movement of the poles helps the uneven distribution of lithospheric plates on the surface of the Earth.
The symmetry of the drift of the continents and the poles
Petrella and colleagues by modeling and experiments that are carried out for five years, came to the conclusion that the change of the magnetic poles occurs when boards are unevenly distributed, that is concentrated in a single hemisphere. For example, according to Petrella, about 200 million years ago, the supercontinent Pangea, which united most of the Earth's land, began to split into smaller parts. Given this fact, the researchers compared the distribution of parts of the former supercontinent in the northern and southern hemispheres with known change in the magnetic poles.
It was found that the degree of symmetry in the arrangement of continents changed just before the next inversion.
Why is it so
With regard to the mechanisms of how the location of plates may be due to the magnetic poles, scientists have the following assumption. Lithospheric plates to sink into the mantle at a considerable depth in the so-called subduction zones, thereby changes the properties of the mantle, which led to modifications to the kernel. A recent change caused the magnetic poles.