# Seismic Reflection Analysis of AETA Electromagnetic Signals
## 5 Conclusions  
In this study, the LAE and IQR methods were utilized to analyze the electromagnetic signals of the AETA stations near the Jiuzhaigou and Yibin epicenter. The results show that the electromagnetic signals of the AETA stations are obviously abnormal before the two earthquakes. First, the time, value, and number of abnormal points in stations at different geographical locations are not consistent, which is probably due to the difference of geological structure and the distance from the epicenter. The stations that were further away from the epicenter may show stronger anomalies than those closer. In general, there was obvious abnormal information about half a month before the earthquake. Secondly, the stations near the seismic epicenter generally exhibited outliers accounting for \(2\sim 4\%\) of the total data, and some stations had outliers with anomaly values exceeding 0.7 before the occurrence of a large earthquake, which shows that the electromagnetic anomaly of the AETA station has a certain correlation with the earthquake. Finally, comparing the methods of LAE and PCA through the case of the Jiuzhaigou earthquake, we found that the abnormal performance of the station is more common based on the LAE method, and that the ability to respond to abnormalities is also stronger and more intuitive. While the PCA method has good earthquake reflection performance at the JZG station, the performance of the other stations is not effective, which further proves the robustness of the LAE method used in this study.  
In summary, the experiment in this study proves that the electromagnetic disturbance anomalies of the AETA station could imply an upcoming large earthquake, and that AETA electromagnetic signals can be regarded as a type of earthquake precursor. According to the experimental results, we believe that if 2% of abnormal points appear in most  
Figure 11: Thermogram of abnormal values in stations within 200 km of the Jiuzhaigou epicenter. (**a**) JZG station; (**b**) SP station; (**c**) PWX station; (**d**) QCX station; (**e**) MX station; (**f**) WC station.  
monitoring stations within half a month, it means that a certain area has a higher risk of strong earthquakes.  
In the future, we consider using a Generative Adversarial Networks (GAN) approach to generate several representative anomalous sequences. When the original signal matches these anomalous sequences, the system can automatically alert, which indicates that a certain area is facing the risk of high-level earthquakes. In addition, due to the complexity of actual seismic activity, it is difficult for us to directly estimate the geographical location of the epicenter from statistical values such as the number and amplitude of anomalous points. The use of AETA electromagnetic signals for earthquake prediction or early warning is awaiting further research in the future.  
Conceptualization, Z.B., S.Y. and C.Y.; methodology, Z.B. and C.Y.; software, Z.B.; validation, Z.B., S.Y. and X.W.; formal analysis, Z.B.; investigation, Z.B. and C.H.; resources, S.Y. and X.W.; data curation, Z.B., J.X. and C.H.; writing--original draft preparation, Z.B.; writing--review and editing, S.Y., X.W. and C.Y.; visualization, Z.B. and J.X.; supervision, S.Y., X.W. and C.Y. All authors have read and agreed to the published version of the manuscript.  
This research was supported by a fundamental research grant from Shenzhen science & technology, grant number JCYJ20200109120404043 and KQTD20200820113105004.  
Not applicable.  
The data presented in this study are available from the authors upon reasonable request.  
The authors declare no conflict of interest.