## 3 Automatic Detection Method
The electron density perturbation searched via the software is denoted by a black arrow. Red arrows stands for plasma bubbles in the electron density, electron temperature, He\({}^{+}\) density, and O\({}^{+}\) density from the top panel to the bottom panel. Figure 6: Kp variations during 20 January–3 February 2024. Figure 8: Variations in plasma parameters along the night orbit 33251 on January 29 2024. (**a**) Electron density (top line) and electron temperature (bottom line). (**b**) He\({}^{+}\) density (top line) and O\({}^{+}\) density (bottom line). Figure 7: Fluctuations of (**a**) the geomagnetic H component and (**b**) geoelectric EW component during 20–25 January 2024 at the ground-based Hongqian station. An electron perturbation and an O\({}^{+}\) perturbation with magnitudes over 20% were successfully detected in the next week (31 January-6 February 2024), and they have been listed as Pe2 and Pi2 in Table 3. Their relative locations on the map are displayed with blue triangles in Figure 4b. From Table 3, these two plasma disturbances happened on 3 February on the night orbit 33327, one revisiting orbit of 33175 where obvious electron depletion occurred earlier. These two ionospheric variations occurred almost synchronously, with near locations and similar amplitudes of 24.6% for the electron density and 27.3% for the ion density and space sizes of 489 km and 510 km (see Table 3), respectively. Variations in different plasma components automatically output from the CSES data processing system were extracted and are displayed in Figure 9. The two detected ionospheric perturbations are labelled with a blue arrow for the electron density (see the top panel in Figure 9a) and a black arrow for the O\({}^{+}\) density (see the bottom panel in Figure 9b). From Figure 9, it is obvious that almost synchronous fluctuations occurred not only in the electron and O\({}^{+}\) density data but also in the electron temperature and He\({}^{+}\) density measurements. On one hand, the electron density and the electron temperature demonstrate a contrary varying trend where one increases and the other decreases (see Figure 9a), which is highly coincident with what has been reported before [19]. Enhancements of O\({}^{+}\) and He\({}^{+}\) show almost the same pattern when comparing the top panel with the bottom one in Figure 9b, on the other hand. Meanwhile, the Kp index on the same day as plasma perturbations occurred was quiet when we checked this parameter in Figure 6. Thus, these apparent irregularities had been considered as seismic precursors at that time and would be traced continuously in the following days. Figure 9: Variations in the ionospheric parameters along the night orbit 33327 on 3 February 2024. (**a**) Electron density (top line) and electron temperature (bottom line). (**b**) He\({}^{+}\) density (top line) and O\({}^{+}\) density (bottom line). Automatically detected positive electron and O\({}^{+}\) perturbations are denoted by a blue arrow and a black arrow, respectively. The negative irregularity of the electron temperature is labelled by a red arrow and the enhancement of He\({}^{+}\) by a green arrow. However, neither electron perturbations nor ion perturbations with a magnitude beyond 20% had been detected in the next two weeks since 7 February 2024 (see Figure 4c,d). Corresponding fluctuations for various plasma parameters of the following revisiting orbits on 8, 13, 18, and 23 February had been checked and are demonstrated in Figure 10 for the electron density and in Figure 11 for the O\({}^{+}\) density. From Figures 10 and 11, since 8 February, no obvious variations in these two parameters had taken place around the location where strengthened ionospheric irregularities were detected on orbit 33327 on 3 February 2024. Two strong aftershocks with magnitudes of \(M_{\rm S}\) 5.3 and \(M_{\rm S}\) 5.8 took place on 24 and 25 February 2024, in the aftershock area of the Wushi event, with depths of 10 km and 11 km, respectively (Table 2 and red dots in Figure 3).