# Detection of Geomagnetic Signals as Precursors to Some Earthquakes in China
## 5 Conclusions  
We applied polarization analysis to geomagnetic data recorded in the JYG, GLM, and KSH observatories, and obtained the evolution of polarization ratios of \(Y_{\rm ZH}\) and \(Y_{\rm ZG}\) in these stations. The results showed that some significant enhancements (exceeded the threshold value \(m+2\sigma\) by 85%) of \(Y_{\rm ZH}\) and \(Y_{\rm ZG}\) in JYG station occurred a few days prior to the Jinta \(M_{\rm s}\) 5.4 earthquake and lasted for about 2 months. In the case of the Haixi \(M_{\rm s}\) 5.0 earthquake, the polarization ratios of \(Y_{\rm ZH}\) and \(Y_{\rm ZG}\) in GLM station reached an abnormally high value (exceeded the threshold value \(m+2\sigma\) by 72% and 57%, respectively) about half a month before the earthquake and lasted for about 1 month. For the last case, some enhancements (exceeded the threshold value \(m+2\sigma\) by 62%, 69%, and 119%, respectively) of polarization ratio \(Y_{\rm ZH}\) of KSH station occurred 1 month prior to the \(M_{\rm s}\) 7.4, \(M_{\rm s}\) 6.7, and \(M_{\rm s}\) 6.7 earthquakes and lasted for half a month. Compared with the Dst index and reference stations, our preliminary conclusions suggested a close relationship between the enhancements prior to the Jinta earthquake and a series of earthquakes near the KSH station. Nonetheless, the enhancements are not related to the Haixi earthquake.  
The following are available online at [[https://susy.mdpi.com/user/manuscripts/resultm/4d4454a76326d7936](https://susy.mdpi.com/user/manuscripts/resultm/4d4454a76326d7936) fb9c546c5a17 cdc]([https://susy.mdpi.com/user/manuscripts/resultm/4d4454a76326d7936](https://susy.mdpi.com/user/manuscripts/resultm/4d4454a76326d7936) fb9c546c5a17 cdc), Figure S1: Distribution of geomagnetic stations and earthquakes at (a) the national scale, (b) KSH area, (c) JYG and GLM area. Figure S2: Polarization ratios of \(Y_{\rm ZH}\) at (a) JYG, (c) CNH observatories and \(Y_{\rm ZG}\) at (b) JYG, (d) CNH stations about 0.04 Hz from 2011 to 2012 and (e) Dst index. Figure S3: Polarization ratios of \(Y_{\rm ZH}\) at (a) GLM,  
Figure 6: Scatter diagrams of magnitude and epicentral distance for (**a**) 37 and (**b**) 30 earthquakes.  
(c) CNH stations and \(Y_{\rm ZG}\) at (b) GLM, (d) CNH observatories about 0.1 Hz during 2013 and (e) Dst index. Figure S4: Polarization ratios of \(Y_{\rm ZH}\) at (a) CDP, (b) GLM, and (c) CNH stations at approximately 0.1 Hz during 2013. Figure S5: Polarization ratios of \(Y_{\rm ZH}\) at (a) KSH, (c) CNH stations and \(Y_{\rm ZG}\) at (b) KSH, (d) CNH observatories within 0.003-0.02 from 2014 to 2017 and (e) Dst index. Figure S6: Scatter diagrams of magnitude and epicentral distance for (a) 37 and (b) 30 earthquakes.  
Data collection and processing, X.Y. and W.W.; funding acquisition, Y.T.; writing--original draft, X.Y. and W.W.; writing--review and editing, Y.T. All authors have read and agreed to the published version of the manuscript.  
This research is financially supported by the National Natural Science Foundation of China (Grant No. 42164004).  
Not applicable.  
The data presented in this study are available within the article and its Supplementary Materials.  
The authors would like to thank the Geomagnetic Network of China for providing the geomagnetic data.  
The authors declare no conflict of interest.