# Feasibility Study on Earthquake Prediction Based on Imending Geomagnetic Anomalies
## 3 Data Analysis and Prediction Experiments  
According to the data observed from the geomagnetic monitoring network and the data released by the China Earthquake Administration Network Center, a total of eight earthquakes (Table 2) occurred in and around the study area between 10 November 2021 and 6 January 2022. These earthquakes were distributed around the geomagnetic monitoring network, which the minimum magnitude was 3.0 M and the maximum magnitude was 5.5 M.  
The sampled magnetic intensity data are processed according to Formulas (6) and (7), and the length of time window is taken as 90 s, so the geomagnetic anomaly sequence \(A\) shown in Figure 3 can be obtained. The column line sequence in Figure 3 shows the daily average gradient of the geomagnetic anomaly. It can be seen that the gradients of \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Date** & **M** & **Location** &
\begin{tabular}{l} **Epicenter Distance** \\ **(km)** \\ \end{tabular} \\ \hline
17 November 2021 & 3.1 &
\begin{tabular}{l} Xingwen County, Yibin City, \\ Sichuan Province \\ \end{tabular} & 433 \\
21 November 2021 & 4.6 &
\begin{tabular}{l} Changing County, Yibin City, \\ Sichuan Province \\ \end{tabular} & 410 \\
26 November 2021 & 3.3 &
\begin{tabular}{l} Weiyuan County, Neijiang City, \\ Sichuan Province \\ \end{tabular} & 460 \\
1 December 2021 & 4.2 &
\begin{tabular}{l} Changing County, Yibin City, \\ Sichuan Province \\ \end{tabular} & 436 \\
12 December 2021 & 3.0 &
\begin{tabular}{l} Yanyuan County, Liangshan \\ Prefecture, Sichuan P. \\ \end{tabular} & 126 \\
21 December 2021 & 3.3 &
\begin{tabular}{l} Ningnan County, Liangshan \\ Prefecture, Sichuan P. \\ \end{tabular} & 187 \\
2 January 2022 & 5.5 &
\begin{tabular}{l} Ninglang County, Lijiang City, \\ Yunnan Province \\ \end{tabular} & 248 \\
5 January 2022 & 3.9 &
\begin{tabular}{l} Ninglang County, Lijiang City, \\ Yunnan Province \\ \end{tabular} & 246 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Statistics of earthquakes from 10 November 2021 to 5 January 2022.  
geomagnetic anomalies are both positive and negative. The positive indicates that the geomagnetic anomaly becomes larger, the negative indicates that the geomagnetic anomaly becomes smaller, and the black dotted line indicates the date of the earthquake occurrence listed in Table 2. The gradient threshold of the geomagnetic anomalies is set as \(\pm\)200 in Figure 3. Those exceeding the threshold are indicated in red. It can be further seen that during this period of strong earthquakes, the variation of the geomagnetic field is also very large, and the geomagnetic anomalies existed before and after the earthquake. The red magnetic anomaly value in Figure 3 is extracted to obtain sequence \(\mathbf{A}^{\prime}\), sequence \(\mathbf{B}\) is obtained according to the above extraction rules, and sequence \(\mathbf{C}\) is obtained according to Table 2. Figure 4 illustrates a notable correlation between sequence \(\mathbf{B}\) and sequence \(\mathbf{C}\), with a substantial similarity of 85.7%. Therefore, the data in Figure 4 show that during this period (10 November 2021 to 7 January 2022), six of the seven earthquakes had a geomagnetic anomaly before, with a probability of 85.7%, so it is reasonable to predict occurrence of earthquake using the geomagnetic anomaly. Next, we try to use the geomagnetic anomaly before the earthquake to predict its occurrence. As shown in Figure 5, the blue sequence is \(A\), and according to the above extraction rules, the blue column with a red circle is sequence \(\mathbf{B}\), and the black dashed line is sequence C. Therefore, the columns with a red circle are the warning time point. It can be seen that warning signals appeared before the six earthquakes, and a total of seven predictions were made for the eight earthquakes, with six correct, one false, and one missed, resulting in an accuracy rate of 75%, a missed rate of 12.5%, and false rate of 15%.