Seismologists are trying to predict earthquakes from electromagnetic oscillations in the Earth's ionosphere

At the last conference of the American Geophysical Community, scientists shared their experiences in earthquake prediction. In the periods from several minutes to several days before an earthquake, both in the earth's crust and in the atmosphere, electromagnetic fluctuations occur. Their detection and processing can allow seismologists to effectively predict natural disasters.

Japanese geophysicist Kosuke Heki from Hokkaido University in Sapporo, Japan, first noticed this effect in 2011, when the instruments detected a change in the ionosphere's electronic composition 40 minutes before the 9-magnitude earthquake that followed. The discovery was helped by the fact that a geophysicist using data from GPS satellites studied the reaction of the ionosphere to earthquakes. At the moment of movement of the earth's crust, vibration is transmitted throughout the atmosphere to its upper layers.

For several years, he confirmed his observations nine more times , catching changes in the ionosphere before earthquakes occurred. He also found that the stronger the earthquake, the earlier these atmospheric anomalies appear.

The question remains how the movements of the earth's crust lead to the appearance of electromagnetic radiation. Some believe that stony layers heated by pressure are capable of generating positive charges. “When you put a stone under pressure, it turns into a battery,” says Friedemann Freund, an associate professor of physics at the University of California, San Jose. “Not in such an electrochemical battery that is under the hood of your car, but in a new type of semiconductor battery that produces electrons and holes.”

Positively charged holes arise in a crystalline rock in which peroxide bonds are present - in them oxygen atoms are connected to each other, and not to a silicon atom. With increasing pressure and temperature, bonds break, oxygen draws an electron from a neighboring atom, and leaves behind a positively charged “hole”. Neighboring electrons rush into it in turn, which ultimately leads to the described electromagnetic effects.

The same effects explain evidence of unusual phenomena preceding earthquakes, such as a glow that bursts from the ground., and problems with the magnetic compass in the earthquake zone. Frund and colleagues tried to reproduce similar effects in the laboratory, dropping a large mass on the stones, and actually recorded the appearance of electromagnetic pulses.

Jorge Heraud of the Catholic University of Peru said that his team was able to capture electromagnetic pulses in the earth's crust with magnetometers two weeks before the start of the Lima earthquake. True, magnetometers for recording such phenomena should be located no further than 100 km. from the epicenter.

In this regard, seismologists teamed up with a European Space Agency (ESA) project called SWARMstudying the magnetic field of the Earth. The combined data from SWARM, as well as data from GPS satellites and seismometers, can help develop the technology for predicting future earthquakes.

Seismologists have long been trying to find a connection between the ionosphere and earthquakes. Back in 1990, geophysicists from Stanford University discovered low-frequency oscillations in the ionosphere, which began three hours before the 7-point earthquake that occurred in Northern California in 1989.

Unfortunately, many seismologists are not very confident in success. Tom Jordan, director of the Southern California Earthquake Research Center, in his 2009 paper, concluded that there was no evidence of a connection between ionospheric fluctuations and the occurring earthquakes. Even more seismologists believe that even if an earthquake is predicted and possible, this does not mean at all that it will be possible to predict its strength and duration. It is possible that strong earthquakes start just like weak ones.

So far, despite the considerable efforts of seismologists in research, it is impossible to give such a forecast of earthquakes up to a day or even a month. Scientists still do not know all the details of the physical processes associated with earthquakes, and the methods by which they can be accurately predicted.

According to the Seismological Community of America, the claimed forecast method, which could be called correct, should describe the expected magnitude with a certain permissible deviation, a well-defined zone of the epicenter, the range of time during which this event will occur, and the likelihood that it will actually happen. The data on which the forecast is based should be verifiable and the result of their processing should be reproducible.

The ionosphere is a layer of the atmosphere that is highly ionized due to exposure to cosmic rays. On our planet, this is the upper part of the atmosphere, consisting of a mixture of a gas of neutral atoms, molecules and a quasi-neutral plasma. The degree of ionization becomes significant already at an altitude of 60 kilometers.