## 5 Conclusions
As already presented in the discussion section, the statistical results are very consistent among the two works, demonstrating that, even with different decluster parameters in the Reasenberg approach and the slightly different earthquake catalog, the main results of our Worldwide Statistical Correlation (WSC) algorithm are not affected significantly. The reason for this is probably that, in the final WSC results, the bins are generally large in space (3.34\({}^{\circ}\)) and time (from 2.4 days to 20 days), so the low \"space and time\" resolution homogenizes the differences among the two declustered earthquake catalogs. Here, we want to explore how the results are affected by using another declustering technique--in particular, that provided by [PERSON] [55]--or by using the original undclustered catalog. More recent seismological techniques have been developed, such as the Epidemic-Type Aftershock Sequence (ETAS) model that was also applied to decluster earthquake catalogs [56]. The ETAS technique permits the obtention of the probability that an earthquake can trigger another one (or be triggered by another one) and also has some forecast capabilities [57]. ETAS declustering has been applied to global seismicity by [PERSON] et al. [58], but this is beyond of the scope of this paper (to test it by WSC). We propose, as a future improvement, the study of the ionospheric electromagnetic disturbances combined with the ETAS investigation of seismicity. Different decluster techniques have been compared by [PERSON] et al. [59] in terms of the Gutenberg-Richter parameters obtained after declustering the catalog and were also compared with the original catalog. From [59], it is possible to note that [PERSON] [35] and [PERSON] [55] provide a different, non-superposed set of \(a\)- and \(b\)-values of the Gutenberg-Richter earthquake magnitude distribution, so we consider them as independent for the next test. We reanalyzed the _Swarm_ magnetic field data presented in Figure 1 with the [PERSON] declustered catalog and the earthquakes not declustered by associating all the anomalies to all the earthquakes (Method 1). In addition, we also propose Method 3 (maximum magnitude) to analyze the non-declustered catalog, as it could, in principle, provide similar results to a declustered catalog. In fact,the declustering means extracting the mainshocks that have a higher magnitude than the foreshocks and aftershocks. So, associating the anomaly with the maximum magnitude earthquake could mean linking it with the mainshock. Contrariwise, we need to note that the seismic radius used by the decluster techniques tends to be very much smaller (e.g., 10 km) than the [PERSON]'s radius used by our searching algorithm (e.g., \(\sim\)600 km for M6.5), so it is not the same approach as that using the declustered catalog. Figure 11 reports the results of the WSC applied to 8 years of _Swarm_ magnetic field data and M5.5+ shallow earthquakes declustered by the above-mentioned techniques (on the left side: A and C) or not declustered (on the right side: B and D). In subfigure 11, the method of \"Max (magnitude)\" has been applied to the WSC using the non-declustered earthquake catalog (i.e., the original one). It is possible to note that, in any case, some concentrations of anomalies at about 30 days and 80 days before the earthquake are underlined. Such evidence provides more proof that these concentrations are real and, furthermore, that they are not dependent on the way in which the earthquake catalog is treated. Comparing the two results with the declustered catalogs (subfigures 11 and 11), it is possible to note that the results are very similar, even if the decluster technique is different. The pattern of concentrations is almost equal, with slightly differences, and the statistical significance is comparable.