What threatens humanity with the Earth's largest magnetic anomaly

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

MOSCOW, June 13 - RIA Novosti, Vladislav Strekopytov. Recently, the European Space Agency (ESA) reported that, judging by satellite data, the Earth's largest magnetic anomaly began to move, split in two, and changed in intensity. What does this threaten humanity - RIA Novosti figured out.

The earth is like a magnet

It is believed that the magnetic field is associated with the processes taking place deep in the bowels of our planet. The core of the Earth is made of metals. At the same time, its central part, the inner core is solid, and the outer one is liquid. Due to the difference in temperature and pressure, convection occurs, flows of molten iron create an electric current, and that current creates a magnetic field that protects the planet's surface and all living things from solar radiation and dangerous cosmic radiation.

Roughly speaking, the Earth is a magnetic dipole, and its axis does not quite coincide with the axis of rotation of the planet. The deviation is 11 degrees, about the same distance between the geographic and magnetic poles.

But the Earth is not a perfect dipole. The planet's magnetic field is heterogeneous, it contains anomalies caused by the peculiarities of the deep structure and different magnetization of the earth's crust. The largest is the South Atlantic Magnetic Anomaly (SAMA), stretching from South Africa to Brazil.

The deviousness of the magnetosphere

On June 1, 2009, an Air France liner en route from Rio de Janeiro to Paris disappeared from radar. Debris in the ocean was found only a few months later. According to one version, the crash was due to equipment failure in the UAMA zone.

Where everything is in order with the magnetic field, the charged particles of cosmic rays and the solar wind - electrons and protons, slow down already at a distance of 60 thousand kilometers from the surface, and they usually do not get closer than 1300-1500 kilometers. This is considered the lower boundary of the radiation belt. And only in the area of the South Atlantic anomaly, where the field is very weak, the radiation approaches the Earth by 200 kilometers.

This is especially dangerous for low-orbit satellites and space telescopes - they are at about this height. As a result, unprotected electronics can malfunction. So, in 2007, the first-generation American communication satellites Globalstar were disconnected in the UAMA, and in 2016, the Hitomi orbital X-ray observatory of the Japanese Aerospace Research Agency went out of order and collapsed. The Hubble Space Telescope is being put into sleep mode over the South Atlantic Anomaly.

© ESA

The points where the Swarm satellites recorded the effects of cosmic radiation in the period from April 2014 to August 2019. The maximum is concentrated in the UAMA zone

Something is happening to the Earth

To study the planet's magnetic field in 2013, ESA launched the Swarm mission of three satellites, capturing all signals emanating from the core, mantle, earth's crust and oceans, as well as the main parameters of the ionosphere and magnetosphere.

The earth's magnetic field is strongest near the poles. The weakest of all is in UAMA. Measurements from the Swarm satellites have shown that the anomaly is growing.

The ESA website reports that from 1970 to 2020, the JAMA border moved westward at a speed of 20 kilometers per year, with the minimum field strength dropping from 24 to 22 thousand nanotas. It is estimated that the expansion of the SAAMA has weakened the Earth's magnetic field by nine percent over the past two centuries, and now this process has accelerated by an order of magnitude - tensions are decreasing by five percent in a decade.

Several years ago, a second center of minimum tension began to form in South AMA, and now the anomaly has practically split into two parts - Brazilian and Cape Town. And this means that soon another zone of increased danger for satellites and space stations may appear.

© ESA / Division of Geomagnetism, DTU Space

The emergence of two centers at the South Atlantic Magnetic Anomaly

Scientists cannot yet unambiguously explain such a rapid change in the magnetic field in this part of the globe. One of the versions: under the southern part of Africa, on the core-mantle border, there is an area with reverse magnetic polarity, which creates the anomaly. Here, at a depth of about 2,900 kilometers, lies an area of dense rock that geophysicists call a low shear province and geologists call a superplume. Perhaps for some reason, these rocks began to move, which affected the anomalies.

© Photo: Michael Osadciw / University of Rochester

South Atlantic Magnetic Anomaly (blue lines) and mantle superplume (green spot)

Two northern "drops" pulling the pole

In the past twenty years, the magnetic north pole has also been rapidly shifting. This creates serious problems for navigation systems of various levels - from maritime transport to Google maps in household smartphones, since they are all based on an accurate reference to the geographical coordinates of the magnetic pole, which is indicated by the arrow of any compass.

Satellite geophysical data made it possible to explain this phenomenon. It turned out that anomalies are to blame here, in this case, positive ones. One of these zones of a strong magnetic field, resembling a drop in shape, is located under Northern Canada, the other - under the Siberian shelf. The Canadian "drop" began to decrease, and the Siberian - to increase, and the pole sharply shifted in its direction.

© ESA

Magnetic anomalies and displacement of the magnetic north pole

Local anomalies

In the 1960s and 1970s, NASA launched a series of satellites to study the Earth's magnetosphere. After processing the results, experts from the Goddard Space Flight Center built a map of surface magnetization, on which only anomalies associated with the peculiarities of the composition of the earth's crust rocks are noted, without taking into account the Earth's dipole field.

The map shows that the thinner and younger oceanic crust is less magnetized than the thick and ancient crust of the continents. But there are also nuances here.

Magnetization map of the earth's crust, according to NASA satellites MAGSAT, OGO-2, OGO-4 and OGO-6. Red and yellow are zones with high magnetism, blue and blue are zones with low.

Local magnetic anomalies on the continents are associated with the features of the upper crust - the depth of the crystalline basement or large accumulations of iron-bearing rocks. The Kursk Magnetic Anomaly (KMA) above the world's largest iron ore basin and the Bangui magnetic anomaly in Central Africa, whose origin still remains a mystery to scientists, are especially clearly distinguished.

In those places of the KMA, where the iron ore deposits come close to the surface, the compass needle begins to rotate chaotically. So at one time geologists and found here the first deposit.

Doctors have found that prolonged exposure to an abnormally high natural magnetic field reduces immunity, disrupts systemic functions of the body and accelerates aging. But not all residents of the KMA fall into the risk group (the anomaly covers the Kursk, Belgorod and Voronezh regions), but only those who are in direct daily contact with magnetic ore - workers of mining and processing enterprises.