Geophysicists have developed a simple and not resource-intensive software tool that allows you to identify the gravitational waves, caused by earthquakes. Since gravitational waves travel at the speed of light, the new method will help to detect earthquakes much earlier than the seismic stations will come conventional seismic waves, for example, that in the event of a tsunami could save many lives. A study published in the journal Earth and Planetary Science Letters.
The earthquake provoked a rapid redistribution of mass within the Earth and generate seismic waves — longitudinal waves of compression (P-waves) and shear waves (S-waves), which propagate along the surface and in the rock. The P-wave velocity from 8 to 13 kilometers per second, depending on the properties of the medium, and S-waves is approximately two times less. In addition, earthquakes and give rise to gravitational perturbations, i.e. gravitational waves. They move at the speed of light, and therefore can reach distant seismic stations much earlier than the fastest seismic P-waves.
In the early 2000 years, scientists tried to detect those disturbances that should arise until the arrival of P-waves. They used a superconducting gravimeters able to feel the vibrations of the gravitational field of the order of 10 nanogel (1 Gal corresponds to 0.01 of the gravitational acceleration), but the signal from the earthquakes was not possible to isolate from background noise and artifacts.
Finally, in 2016 the French geophysicist Jean-Paul Montagnier (Jean-Paul Montagner) and his colleagues were able to isolate the gravity signal of the earthquake. They analyzed the data collected during the powerful earthquake in Japan in March 2011, the magnitude of which reached 9.1. This earthquake caused a tsunami that triggered the disaster at the plant in Fukushima. During the earthquake in Japan worked Kamioka Observatory superconducting gravimeter, the only one in Japan who was doing measurements with sufficient for analyzing a frequency of once per second. The amplitude amounted to about 0.15 microgal that was in harmony with the predictions of theoretical models (0,1 microgal).
However, in this case it was an extremely powerful earthquake, attempts to capture the signal less strong earthquakes requires first to derive a prediction of how it will look like the desired gravitational signal. This task can be very complex, as gravitational waves propagating in the Earth provoke the secondary seismic waves, to create additional “noise”, which greatly complicates the modeling.
To solve this problem came from scientists of the German Center of Geosciences in Potsdam and the University of Beijing under the leadership of Sebastian Heimann (Sebastian Heimann). They modified the program QSSP, which the original was intended for the synthesis of seismograms for spherically symmetric Earth model taking into account the influence of the oceans and atmosphere.
Previous software tools that were used for simulation of gravitational waves earthquakes were very complex and require high computing power. The new approach allowed to solve the problem more accurately, but without the involvement of powerful computers. Using this new algorithm, the researchers conducted a simulation of gravitational waves from the 2011 earthquake. These data are well consistent with the simulation results of other groups, who used much more sophisticated models and more powerful computers.
According to scientists, they have developed method allows to significantly simplify the identification of the gravitational signals, but to create new systems for early warning of seismic shaking necessary to create a new, more sensitive gravity meters and infrastructure.
About whether it is possible to predict earthquakes, read in our blog. For warning of earthquakes now offer an increasing number of configurations of different sensors, e.g., based on accelerometers in smartphones or fiber optic cables.