José Manuel NievesSEGUIR Updated: Save Send news by mail electrónicoTu name *
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A new study conducted by researchers from the universities of Leeds, in the Uk, and California, in San Diego, lets just give another twist to the thorny issue of the behavior of the magnetic field of the Earth, which depends, in good measure, our survival.
Recently published in Nature Communications, the new research has revealed, in effect, that changes in the direction of the magnetic field of the planet can be up to ten times faster than was thought until now. The work offers a new vision of the flow of iron to 2800 km depth under the earth’s surface, and shows how that flow has impacted on the movement of the magnetic field during the last hundred thousand years.
As is well known, the magnetic field of the Earth is generated and maintained by a convective flow of the molten metal that forms the outer core of our planet. The movement of the liquid iron creates electric currents which feed the field, and that not only helps us to guide the navigation systems, but also keeps the atmosphere in place and protects us, at the same time, the harmful radiation from the Sun and other sources more distant.
however, the magnetic field is not fixed, but changes constantly. During the past few years, satellites have provided new means to measure and track these changes, but the field has existed since long before even the existence of man, and is ignored to a large extent how they behaved in the past.
The magnetic field of the past
To know how was the magnetic field in geological times, scientists typically analyze the address magnetic tape recorded in ancient rocks, sediments, , lava flows, or even tools made by man. However, the task is not straightforward, and the rates of change obtained by these procedures are subject to intense debate.
Now, Chris Davies, University of Leeds, and Catherine Constable, of the of California, San Diego, have managed to approach the issue from a different point of view. And to do this combined simulations of the process of generation of the field with a reconstruction recently published his variations for a period that spans the last 100,000 years .
The study has shown that the changes in the direction of the field have gone on to achieve rates that are up to ten times faster than those reported in the present. The variations came, in effect, to be of more than one grade per year.
Changes associated with periods of weakening
Davies and Constable showed, moreover, that these rapid changes are closely associated with periods of weakening the local magnetic field. Which indicates that these changes were usually in moments in that the field reversed its polarity (the magnetic north pole was going to be the magnetic south pole and vice versa), or during the “excursions geomagnetic” during which the magnetic poles are rapidly moving toward the north or toward the south (as is happening now, with the magnetic north pole moving toward Siberia at a speed of about 60 km per year).
The most obvious example of this situation, however, was the sudden change of direction of approximately 2.5 degrees that took place to 39,000 years. The change occurred in a region just off the west coast of Central America, where the strength of the field was locally weaker, and it came to pass just after the “trip global Laschamp” , a brief reversal of the magnetic field that is produced makes some 41,000 years. The researchers also identified other such events during the period studied.
Patches of reversed flow
According to the study, the directional changes more rapid are associated with the movement of patches of reversed flow” of the liquid iron through the surface of the outer core. These patches are more common in lower latitudes, which suggests that future searches should focus precisely on those areas.
In the words of Davies, “we still have a knowledge is very incomplete of our magnetic field beyond 400 years ago . And since these rapid changes reflect some of the events more ends of the liquid core, could give us important information about the behavior of the deep interior of the Earth.”
Constable, for his part, believes that “to understand whether the computer simulations of the magnetic field reflect, or do not, accurately the physical behavior of the geomagnetic field as inferred from the logs can prove very difficult. In this case, however, in our simulations we have been able to show an excellent matching both in the rates of change as in the general location of the events more extreme.
The study provides a useful strategy to document how these changes happen fast, and if you also give in times of magnetic polarity stable, like the one we are experiencing today”.
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