## 3 Results
### Single-Orbit Analysis
The red star represents the epicenter position, the blue oblique line in the left diagram is the orbit track, the red circles indicate the regions where the perturbation occur for each parameter, and the dotted lines represent the latitude location of the epicenter. with the incoming EQs, so a possible interaction with the seismo-induced phenomenon could not be excluded, even if it is more plausible than the external perturbation source. In this study, we analyzed the electric field data recorded by the Electric Field Detector (EFD) onboard the CSES-01 to determine the possible driving sources of plasma perturbations. The electric field data use the geographic coordinate system (+X indicates the direction that the center of the earth points to the prime meridian along the equatorial plane, and +Z indicates the direction that the center of the earth points to the North Pole) [24]. As presented in Figures 4 and 5, there were disturbances in the vertical direction of the Ultra Low Frequency band (ULF; the range is 0.5-16 Hz, with a resolution of 1 uV/m) waveform of the EQs\({}^{\prime}\) anomalous orbits, which were completely synchronized with the plasma perturbations at the same positions. Figures 6 and 7 show the simultaneous perturbation of multiple plasma parameters recorded in orbits 3458_1 on 17 September 2018, 11 days before the Ms 7.4 Indonesia EQ, and orbit 3806_1 on 10 October 2018, 1 day before the Ms 7.1 Papua New Guinea EQ, which have similar characteristics as Figures 4 and 5. Certain synchronous variations in _Te_, _Ne_, _No\({}^{+}\)_, _V\({}_{z}\)_, _Ex_, and _E\({}^{\prime}\)_ data above the area of \(\sim\)100 km southeast of the epicenter are discernible. On other days, no clear perturbations are shown. Among them, the relative variation characteristics of _No\({}^{+}\)_ and _V\({}_{z}\)_ are the most significant plasma, compared to the relative smoothly feature of _Te_ and _Ne_ values in this area. A noticeable difference between Figures 4 and 5 is that the locations of the disturbances in these two EQs occurred south of the epicenters. At the same time, the two Loyalty Islands EQs appeared in the north of the epicenters. The different geomagnetic latitudes of these EQs, as shown in Figure 1, could explain this apparent discrepancy, even if they were all in the same geomagnetic southern hemisphere. Considering the PAP's contamination, we selected revisiting orbits in the short term, about 25-30 days around the EQs, to ensure the dataset's reliability and reduce some factors related to seasonal changes, longitude position differences, etc. Their relative changes can somewhat reflect the precursor characteristics of EQ events that occurred in close locations in this short time. Taking Figure 8 as an example, five revisiting orbits of orbit 2939_1 (shown in Figure 4) on 14 August were chosen to build a background trend, which are 2787_1 (ten days before, 4 August), 2863_1 (five days before, 9 August), 3015_1 (five days after, 19 August), 3243_1 (twenty-five days after, 3 September), and 3319_1 (thirty days after, 8 September). In the meantime, on 24 and 29 August, the observations were greatly disturbed by the strong geomagnetic storm around 26 August (as shown in Figure 2), so they were not selected for analysis of seismo-ionospheric anomalies. We used the inter-quartile ranges (IQR) method for comparing the \(No^{+}\) and \(V_{z}\) data of orbit 2939_1 with their backgrounds and thus identified the anomalous data. The median and IQR values are statistical parameters, which are equal to the second quartile and the difference between the third (Q3) and first quartile (Q4). The median and IQR values are statistical parameters, which are equal to the second quartile and the difference between the third quartile and the difference between the third quartile. Figure 6: Same format as Figure 4, but the synchronous abnormal perturbations of \(Te,No^{+},V_{z},Ex,\) and \(Ez\) recorded by orbit 3458_1 on 17 September 2018, 11 days before the Ms 7.4 Indonesia EQ influential area.