Scientists have found that five days before an earthquake, the parameters of the internal gravitational waves in the atmosphere change. This information can help develop short-term earthquake prediction methods. The results of the study are published in the journal “Reports of the Academy of Sciences.”
Geophysicists processed satellite data obtained during earthquakes in Uzbekistan on May 26, 2013, in Kyrgyzstan on January 8, 2007, and in Kazakhstan on January 28, 2013. It turned out that five days before the seismic catastrophe, in all three cases the parameters of internal gravitational waves (IGW) changed – oscillations of air masses, which, in contrast to sound waves, have, in addition to longitudinal waves, a transverse component.
The studies were conducted by Russian scientists from the Institute of Dynamics of Geospheres of the Russian Academy of Sciences, IKI RAS and the Higher School of Economics (HSE), headed by academician V.V. Adushkin with the assistance of colleagues from Kyzgyzstan and Germany.
Scientists watched how the temperature of the middle atmosphere (the layer of the Earth’s atmosphere, which includes the stratosphere and mesosphere) behaves over time. Then, the HBV parameters were determined. It turned out that their maximum vertical wavelengths are 14.2 and 18.9 kilometers. It is known that HBV with vertical lengths of more than 10 kilometers occur during convective processes in the atmosphere associated with heating.
* “This means that processes occur in the Earth’s lithosphere, the development of which convective instabilities occur in the lower atmosphere. It is they that cause the HBV in seismically active regions. Internal gravitational waves, reaching the mesosphere, can be destroyed. When this happens, the HBV energy passes into the thermal movement, which affects the temperature, “the HSE press service quotes the words of one of the authors of the study, professor at the HSE Department of Physics, head of the laboratory of IKI RAS Sergey Popel. *
A few days before the earthquake in the earth’s crust, constantly operating global oscillations, seismic gravity waves, are activated, and the flow of hot lithospheric gases leaving the earth’s crust in areas of increased seismic activity is also amplified. All this should affect the temperature and state of the atmosphere, reflecting on a change in the parameters of internal gravitational waves.
The researchers decided to find out what these changes are expressed. It turned out that the wavelength of the HBV in the atmosphere begins to grow in 4-5 days, reaches its maximum value two days before the earthquake and drops sharply the day before the event.
To identify the parameters of the waves associated with the source in seismically active regions, scientists for the first time used satellite-based data on the temperature of the average atmosphere, available on the NASA Giovanny resource. This method greatly facilitates the observation and can serve for short-term prediction of seismic shocks.