Disturbance identification of electric field data observed by the CSES-01 satellite before earthquakes

• Published in: Science China. Earth sciences Vol. 66; no. 8; pp. 1814 - 1824
• Main Authors: Huang, Jianping, Zhang, Fuzhi, Li, Zhong, Shen, Xuhui, Yang, Baiyi, Li, Wenjing, Zeren, Zhima, Lu, Hengxin, Tan, Qiao
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.08.2023; Springer Nature B.V
• Subjects: Amplitude; Amplitudes; Disturbance; Earth and Environmental Science; Earth Sciences; Earthquakes; Electric field; Electric fields; Flight characteristics; Satellite observation; Satellites; Seismic activity; Seismic zones; The CSES-01 satellite; value method; Whistle; Normalization; Electric field
• ISSN: 1674-7313; 1869-1897
• DOI: 10.1007/s11430-022-1048-8

Numerous studies have confirmed that electromagnetic disturbances before earthquakes can be observed by satellites. In this study, we use the C -value method that includes the acoustic whistle signature; pre-seismic ionospheric electromagnetic disturbance signals were acquired based on the CSES-01 satellite electric field data, and the maximum value of C in the earthquake preparation zones increased continuously from 2.0 three days before the earthquake and reached a maximum weight of 3.0 on the day of the earthquake, after the earthquake, it gradually decreased and recovered to about 2.0; its the C values fluctuated between −2 and 3, it is different from the C values range −2–12 of the previous seismic case study using the DEMETER satellite, which may be related to the orbital altitude and revisit period of the satellite. Then, the C values were normalized, and the time series analysis of the obtained θ values were done, and the results showed that: In the pregnant zone, the background variation of the disturbance amplitude θ is within 2 σ , and the maximum disturbance amplitude of θ starts to increase gradually from the seventh period (one period of 5 days, i.e., 35–39 days before the earthquake), it reached 2 σ by the fourth pre-seismic cycle (20–24 days before the earthquake), and then dropped sharply to about 1.5 σ in the third pre-seismic cycle (15–19 days before the earthquake), after two cycles of increase, the θ over the epicenter reached a maximum of 2.1 σ at the time of the earthquake (combining the time of the earthquake and the satellite flight characteristics, the epicenter period is defined as January 25–January 29, 2020, and this defines the study time period line), and the θ decreases to within 2 times the standard range after the earthquake; The negative value of the disturbance amplitude θ in the central region of the pregnant seismic zone during the earthquake shows the transient energy release process. Through comparison, the θ values obtained by normalization based on the C -value method takes into account the variation of the background field, and the result can better reflect the energy change of the ionospheric field before the earthquakes.