Abstract
In order to find out whether the geomagnetic storms and large-mega earthquakes are correlated or not, statistical studies based on Superposed Epoch Analysis (SEA), significance analysis, and Z test have been applied to the Dst index data and M ≥ 7.0 global earthquakes during 1957–2020. The results indicate that before M ≥ 7.0 global earthquakes, there are clearly higher probabilities of geomagnetic storms than after them. Geomagnetic storms are more likely to be related with shallow earthquakes rather than deep ones. Further statistical investigations of the results based on cumulative storm hours show consistency with those based on storm days, suggesting that the high probability of geomagnetic storms prior to large-mega earthquakes is significant and robust. Some possible mechanisms such as a reverse piezoelectric effect and/or electroosmotic flow are discussed to explain the statistical correlation. The result might open new perspectives in the complex process of earthquakes and the Lithosphere-Atmosphere-Ionosphere (LAI) coupling.
Highlights
The electromagnetic anomaly prior to large earthquakes has been intensively investigated during the past decades [1,2,3,4,5,6,7,8,9,10,11,12,13]
The common period for observing more geomagnetic storms is around 27 days before the earthquakes. This phenomenon is not clear for deeper cases (≥60 km) as shown in Figure 7c, implying that geomagnetic storms are more likely to be related with shallow earthquakes rather than deep ones
Further analysis to check the statistical result is applied by calculating the cumulative hours of geomagnetic storms each day
Summary
The electromagnetic anomaly prior to large earthquakes has been intensively investigated during the past decades [1,2,3,4,5,6,7,8,9,10,11,12,13]. Some researchers studied the possible links among earthquakes, solar activity, and geomagnetic storms, and they revealed the seismicity of the earth may be related to the solar activity [20,21,22,23,24,25,26,27,28,29]. There are still active debates on the linkage between the solar-terrestrial disturbance and earthquakes. Some studies suggest insignificant solar-terrestrial triggering of earthquakes and conclude that geomagnetic storms do not trigger earthquakes [31,32]
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