Pre-seismic multi-parameters variations before Yangbi and Madoi earthquakes on May 21, 2021

On May 21, a Ms6.4 earthquake occurred in Yangbi, Yunnan Province. Less than 5 ​h later, on May 21, follows a Ms7.4 earthquake in Madoi, Qinghai Province. In this study, multiple parameters are studied from CSES-01 satellite and GNSS. The parameters include the electron density from LAP, energetic particle flux from HEPP, electric field spectrum from EFD, induced magnetic field spectrum from SCM, and global TEC from ground-based GNSS receivers. In the time scale, all parameters changed on May 15, 17 and 18. The relative amplitude of Ne is more than 200%. In space scale, the clear enhancement focus on the southeast of the epicenter of Madoi, Qinghai, and the shape of the focus region is like a clockwise-30°-rotated rectangle, which is about 45° in length and 20° in width. Moreover, there appeared enhancement in the conjugated region. According to the day-to-day analysis of the low-frequency (75–90 Hz) spectrum of EFD and SCM payloads, the relationship of the increment on May 18 could be confirmed with the successive two earthquakes. The energetic particle fluxes enhanced on May 20. All those changes are located in the east of the following epicenter and appeared just several days before, which could be well explained by the Lithosphere-Atmosphere-Ionosphere theory.