## 3 Results
### Swarm Magnetic Field Results
In Figure 2B, we can see that, in the four larger magnitude bands (i.e., for M6+), the absolute maximum concentration increases perfectly with the magnitude. The anticipation time in the function of the magnitude is presented with a fit (as determined by the Rikitake law, i.e., log\(\Delta T\) = \(a+bM\)) in Figure 2A, where \(a\) = \(-\)0.96 \(\pm\) 0.73, and \(b\) = 0.51 \(\pm\) 0.10. For the lower magnitude earthquake bands (i.e., 5.5 \(\leq\) M \(\leq\) 5.9), the maximum concentrations are at \(-\)210, \(-\)150, and \(-\)90 days, but at the beginning of the graph (where we expect the maximum concentration corresponding to this band), there is also a high concentration of anomalies. We can explain such results in different ways, either independently or occurring simultaneously. One explanation is based on the fact that the lower magnitude earthquakes, i.e., those below M6.0, are less likely to produce distinguishable LAIC effects, while only a part of them can still show some possible ionospheric earthquake precursors. Furthermore, eventual ionospheric electromagnetic perturbations from lower magnitude earthquakes could be very much weaker, and the method presented in this paper could be insufficiently sensitive to detect all of them. An alternative explanation is that these lower magnitude earthquakes are so frequent that an anomaly can be associated with many of them, including those with a longer anticipation time. A third possible reason is that this lower magnitude band could have a typical anticipation time of less than 20 days, which is the most affected by the removal of earthquakes at these distances from larger earthquakes due to the applied declustering method. Despite these considerations, we noted that, in the Rikitake law of Figure 2A, the \"not aligned\" magnitude band with the fit is the one with earthquakes in the range of 6.0 \(\leq\) M \(\leq\) 6.4. Future investigations are necessary to clarify such ambiguity. A summary view of the WSC analysis of the _Swarm_ magnetic field data applied to all the investigated M5.5+ earthquakes is provided in the Supplementary Materials in Figure S3, showing higher concentrations toward the earthquake occurrence. To validate such results, an earthquake catalog with a shuffled magnitude has been produced, and we showed the results in Figure S4 in the Supplementary Materials. In the subplot on the left, it is possible to see that a correlation between the shuffled earthquake magnitudes and the real set is practically absent (R = 0.0004), while, on the right side of Figure S3, it is shown that the relationship between the anticipation time and the earthquake magnitude is lost, as expected after shuffling the earthquake catalog. Some minor correlations can still be found, but this could simply be due to the fact that, since we shuffled only magnitudes, the epicenter and the origin time of the events are still real, so the anomalies really preceded an earthquake. Figure 3 shows the different analyses of the _Swarm_ Y-East component magnetic field data, taking into account the signal's frequency correlated with M5.5+ earthquakes. For these analyses, we show the classical WSC with Method 1 (all possible combinations of anomalies and earthquakes) from 500 days before until 500 days after the earthquake. The periods are from the upward shorter period (2-10 s) (subpanels A) to the downward longer period (25-50 s) (subpanel C). We can note that it seems that the anticipation time increases  
Figure 2: Correlation of _Swarm_ magnetic field anomalies with earthquakes divided into five magnitude bands. (**A**) Fit of the anticipation time of maximum concentration (underlined by a red circle in subfigure (**B**) as a function of earthquake magnitude using the equation \(\Delta T=10^{4+b\cdot M}\). The error bar takes into account the width of the pixel. (**B**) Details of the analysis in the earthquake magnitude bands of 5.5 \(\leq\) M \(\leq\) 5.9, 6.0 \(\leq\) M \(\leq\) 6.4, 6.5 \(\leq\) M \(\leq\) 6.9, 7.0 \(\leq\) M \(\leq\) 7.4, and M \(\geq\) 7.5.