## 4 Discussion
Moreover, these earthquakes may look as addressed (targeted) because they occurred exactly near the footprint of geomagnetic lines filled with relativistic electrons precipitating from the outer radiation belt due to geomagnetic storms. Moreover, the time delay between the onset of a geomagnetic storm and the occurrence of an earthquake may vary from weeks to months. This means the solar wind energy is somehow delivered to some regions of the lithosphere. For several weeks or months, it somehow prepares rock media in those regions for destruction in a kind of earthquake. These results may be helpful for the further development of mathematical models of the solar-terrestrial coupling stated in [61]. Figures 9 and 10 compare temporal variations in global seismicity, sunspot numbers, and galactic cosmic rays. Understandably, the rows of seismic and cosmic ray data were relatively short in comparison with sunspot data, which have been known about since 1755; nevertheless, a tendency of increasing global seismic activity with decreasing sunspot numbers and increasing galactic cosmic rays is evident and agrees with the findings of other authors, e.g., [50; 51; 52; 53]. The dashed red square in Figure 10 marks the cluster of five mega-earthquakes in 2004-2012. The clustering started shortly after the giant magnetic storm in late October 2003, which provoked the long-lived storage of relativistic electrons forming around L\(\sim\)1.5. This storage persisted for more than 2 years (\(\sim\)26 months). It could have been repeatedly replenished with high-energy charged particles during other geomagnetic storms, as seen in Figure 5. Such an assumption does not seem very irrational because in [60], it was found that the delay time can be as long as several years for very strong earthquakes (Mw7.5+). It is necessary to mention that after a cluster of strong earthquakes at the beginning of the 21 st century (and especially after the M9.0 event in Japan), at the meeting of the Seismological Society of America in 2011, a heated debate ensured regarding whether the observed temporary clustering of strong earthquakes had some physical cause [49; 63]. It was noted [49], \"If global clustering of earthquakes is so important that it should be taken into account when assessing seismic hazard, then seismological data should reject the \"null hypothesis\" that the temporal distribution of earthquakes on the planet is described by the distribution Poisson (uniform distribution of random independent events that occur at a constant speed).\" However, questions immediately arose about the reliability of the results of such testing conducted on a time-limited sample of sporadic events (which are the strongest earthquakes). In [64], the effectiveness of traditional statistical tests to unambiguously answer the question of the existence or absence of the clustering of earthquakes in catalogs with a small number of events was evaluated. It was concluded that the test results cannot be considered reliable then analyzing a relatively short sample with rare events. Thus, it was concluded [49], \"... even if there is a global process leading to the generation and clustering of earthquakes, the length of the instrumental seismological series is currently too small to discover reliably. This situation may change either with the accumulation of seismological data in the future or with the advent of the physically justified hypothesis of earthquake generation, which will positively affect the test results.\" We can consider a new hypothesis that the Sun could be a significant earthquake-provoking agent [4]. One of these hypotheses [61] suggests that electromagnetic earthquakes are triggered by a sharp rise of telluric currents in the lithosphere due to the interaction of solar flare X-ray radiation with the ionosphere-atmosphere-lithosphere system.