## 4 Statistical Analysis of Earthquakes  
A total of 12 Ms \(>5.0\) earthquakes were selected within the research area, of which satellite data before and after the Ms 5.4 earthquake off the east coast of Honshu, Japan, on 29 November 2019 were unavailable, so this earthquake was not investigated. The remain ing earthquakes were investigated in detail. The 11 earthquakes mentioned above cannot be fully displayed due to the large number of figures. Without loss of representativeness, we describe only the Ms 6.5 earthquake off the west coast of Honshu, Japan, on 18 June 2019, in detail. An Ms 6.5 earthquake occurred on 18 June 2019, off the west coast of Honshu, Japan, at 38.56\({}^{\circ}\) N latitude and 139.52\({}^{\circ}\) E longitude at a depth of 20 km. While screening all the up-orbit data for the area around the epicenter, we found two groups of up-orbit trajectories passing near the epicenter, as shown in Figure 1. The pentagram in Figure 1 indicates the epicenter. We found that the western orbital group is closer to the epicenter, while the eastern orbital group is farther away from the epicenter, but both orbital groups occur within 10\({}^{\circ}\) of the epicenter. Therefore, these two orbital groups are systematically studied in the following. Notably, the sudden disturbance changes in the results in the region above 50\({}^{\circ}\) N and near the region above 50\({}^{\circ}\) S were due to the disturbances caused by switching the measurement mode in CSES operation, and these disturbances are retained in this paper. Figure 1: Two groups of CSES up-orbit trajectories near the 18 June 2019, Ms 6.5 earthquake off the west coast of Honshu, Japan. Study of the Western Orbital Group Associated with the 18 June 2019, Ms 6.5 Earthquake off the West Coast of Honshu, Japan  
Orbit data of the up-orbit group were selected from 90 days before to 30 days after the earthquake under the condition of space magnetic disturbance (Dst \(\geq-\)30 nT and Kp \(<\) 3) according to the research method. Then, the spectral time-series data of the three geomagnetic components, i.e., the horizontal north-south component, horizontal east-west component, and vertical component, were filtered, as shown in Figures 2a, 3a and 4a, respectively. The curves with the different colors in the figure represent different periods, i.e., different orbital data, which were limited from \(-\)60\({}^{\circ}\) S to 60\({}^{\circ}\) N from 90 days before to 30 days after the earthquake. The unit is nT/Hz, and the values varied at different latitudes. The spectral time-series data of the three geomagnetic components also have different values at the same latitude at different times in Figures 2a, 3a and 4a, respectively. The Figures 2a and 3a reveal that some perturbation data occurred near the epicenter (the vertical dashed line in the figure indicates the latitude of the earthquake, the red rectangular box indicates the location of the perturbation, and the other subfigures refer to Figure 2a). The north-south and east-west component spectra of the horizontal component within the 10\({}^{\circ}\) latitude range from the epicenter from 90 days before to 15 days after the earthquake were subjected to time-series analysis, as shown in Figures 2b and 3b, respectively. In terms of subfigure b, every curve in subfigure b was the amplification from subfigure a within the 10\({}^{\circ}\) latitude range from the epicenter from 90 days before to 15 days after the earthquake. The curves with the different colors in subfigure b represent different periods, i.e., different orbital data, which were limited from 28.5\({}^{\circ}\) N to 48.5\({}^{\circ}\) N. The horizontal dashed line indicates the latitude of the epicenter, the diagonal vertical dashed line indicates the approximate time of the earthquake and the red pentagram indicates the epicenter (refer to Figure 2b for a description of the dashed lines in subfigure b).