Magnetic Storms And Earthquakes

For years scientists have been studying the impact of different geophysical fields on the earthquakes occurrence. It has been assumed that the fields, generated due to the solar activity, earth flows fluctuations, the Earth`s speed of rotation and even the launch of magnetohydrodynamic generators affect the strained state of the earth`s crust, these fields `pumping` additional energy into the crust. Normally the aroused earthquakes are recorded several days after the provoking key event.

Specialists from the Shmidt United Institute for Physics of the Earth, Russian Academy of Sciences, assume that magnetic storms are also powerful enough to quake the earth`s crust. To verify the hypothesis, the researchers compared more than 14,000 earth`s crust vibrations of sufficient power recorded since 1975 in Kazakhstan and Kirgizia, and approximately 350 sudden magnetic storms recorded within the same period by the world geomagnetic observations network.

Geomagnetic storms usually arise due to the high-speed plasma streams ejection on the Sun which accompany the solar flares activity. The air-blast produced by the high-speed plasma streams ejection hits the Earth magnetosphere causing the vibrations. The beginning of the storm which lasts from several hours to several days can be sensed almost simultaneously all over the Earth. Then the storm is replaced by a longer recovery stage, when the Earth magnetic field is gradually restored. At this stage the magnetic field characteristics vary considerably in different latitudes.

The calculations have proved that the greatest number of earthquakes in Kazakhstan and Kirghizia occurs within a several-day period after the beginning of the magnetic storm. Normally the number of earthquakes increases noticeably after a magnetic storm takes place. Nevertheless, in some areas the opposite regularity has been observed. In order to account for other factors (possibly of no less importance), the scientists have tried to trace a connection between the above earthquakes and the tidal fluctuations. However, according to the statistical analysis the tidal fluctuations, unlike geomagnetic storms, have no impact on the earthquakes.

The scientists have also tried to estimate whether the magnetic storm energy is sufficient to provoke an earthquake. In general, the seismic activity releases the energy amount comparable with that carried over by the magnetic storm. However, an earth shock consumes only the hundredth part of the involved resilient energy which triggers the process. Besides, the electromagnetic energy of the storm is being converted into mechanical one through complicated effects in the rocks, for instance piezoelectric effect. The efficiency factor of this conversion makes as little as the hundredth parts of a percent. Therefore, the scientists tend to believe that the magnetic storm acts as the earthquake trigger. The geophysics hope to understand better the physical nature of the trigger effect in the course of the future fieldwork and laboratory experiments.