# Successful Tests on Detecting Pre-Earthquake Magnetic Field Signals from Space
## 4 Conclusions  
Between 2014 and 2023, focusing on M5.0+ earthquakes along the Alpine-Himalayan tectonic belt, we specifically analyzed 1077 earthquakes in the preceding 10-day period. Each earthquake underwent magnetic field signal analysis from the lower-orbit Swarm satellites, i.e., Alpha and Charlie, covering the 10 days preceding each earthquake event. Our scrutiny identified anomalies meeting predetermined anomaly criteria. Subsequently, our findings revealed a statistically significant correlation between earthquake magnitude and the duration and amplitude (\"energy\") of the identified anomaly. Similar correlations were found also for other anomaly parameters, including the distance between the satellite anomaly and the earthquake epicenter. To ensure the robustness of our results, a confutation analysis was conducted. In this analysis, when earthquake epicenters were displaced in latitude from their original positions, many less real satellite anomalies were detected and no significant correlation was observed between earthquake magnitude and the duration and amplitude of the chosen anomaly. This result reinforces the validity of our actual findings and refutes the possibility that they are merely the outcome of random chance. Finally, we also wanted to establish the degree of capability of the method to make predictions, so as to become the base for an OEPS: the high values of the accuracy and of the hit rate are indeed encouraging. However, the still non-negligible value of the false alarm rate suggests some caution before  
Figure 4: Confusion matrix (at **left**) and common calculated performance metrics (at **right**) (e.g., [53]). TP = true positives; FP = false positives; FN = false negatives; TN = true negatives. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Bx, By, Bz** & \multicolumn{2}{c}{**Seismicity**} \\ \cline{2-3}
**Anomalies** & **Y** & **N** \\ \hline Y & 5699 & 800 \\ \hline N & 1126 & 1427 \\ \hline Column totals & 6825 & 2227 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Confusion matrix for the pre-earthquake anomaly detection as obtained from the time series analysis of magnetic field components. Y and N stand for positive (Yes) or negative (No) occurrence of seismicity or magnetic field anomalies. applying the method to real-time earthquake prediction. Another limitation is that the prediction of large-magnitude earthquakes has a large spatial uncertainty, related to the large corresponding Dobrovolsky region. Some indications have been given to improving satellite anomaly identification, reducing the false alarm rate as much as possible, and integrating analysis of the satellite data with other data from the ground, atmosphere, and ionosphere [19; 49]. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/rs16162985/s1](https://www.mdpi.com/article/10.3390/rs16162985/s1)]([https://www.mdpi.com/article/10.3390/rs16162985/s1](https://www.mdpi.com/article/10.3390/rs16162985/s1)), Figures S1-S14; Table S1. [PERSON] was responsible for designing and organizing the work, conducting some data analyses, creating certain figures, and editing the final version. [PERSON] participated in searching the bibliography, performing data analyses, preparing some figures, and writing the first draft of the article. [PERSON] contributed to the organization of the work and the analysis process, validating the results, and reviewing, editing, and finalizing the article's text to conform with the referee and editor requirements. All authors have read and agreed to the published version of the manuscript. The authors would like to acknowledge the financial support of the University of Tehran for this research under grant number 28950/1/09 and that of the Italian Satellite Agency (ASI) in the framework of the Limadou-Science+ Project and INGV and MUR in the framework of Pianeta Dinamico (\"Working Earth\"). The work of ADS has been based on some original research performed within the SAFE (Swarm for earthquake study), funded by ESA.