## 3 Results
### Multi-Parameter Ionospheric Anomalies
#### 3.1.2 GPS-TEC Anomalies  
Based on the anomalous days observed in the GIM data, the GPS stations nearest to the epicenter, such as KIT3, IISC, WUHN, LHAZ, CHUM, and POL200, were selected out of several stations. These finalized stations were considered for anomaly extraction, as shown in Figures 6 and 7. Positive spikes in TEC for the 2015 earthquake can be seen one day before the earthquake on every ground station for almost 30 min, with a prominent difference of 2-8 TECU. On the day following the earthquake, anomalies appeared for POL200 and CHUM, which were the least distant from the epicenter, with a difference of 2-4 TECU, suggesting short-term pre-seismic anomalies.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Date**} & **GIM TEC** & **GPS TEC** & **SWARM** & **Fof2** & & **GIM TEC** & **GPS TEC** & **SWARM** & **Fof2** \\  & **Anomaly** & **Anomaly** & **Ne and Te** & **Anomaly** & **Date** & **Anomaly** & **Anomaly** & **Ne and Te** & **Anomaly** \\  & **(@UTC)** & **(@UTC)** & **Anomaly** & **Presence** & & **(@UTC)** & **(@UTC)** & **Anomaly** & **Presence** \\ \hline \hline \multirow{3}{*}{30-09-2015} & \multirow{3}{*}{9-11 (+)} & \multirow{3}{*}{-} & (-) Ne & & & 1-3, 7-9, & & (+) Ne & \multirow{3}{*}{\begin{tabular}{} \end{tabular} } \\  & & Night/(+) & & & 11-13, 17-19 & & & (+) Ne & \\  & & Day(-)Te & & & & (+) & & Day (+) & \\  & & Night/Day & & & & & & (+) & \\ \hline \hline \multirow{3}{*}{03-10-2015} & \multirow{3}{*}{15-17 (-)} & \multirow{3}{*}{-} & (-) Ne & & & 13-15 GW & & & (+) Ne & \multirow{3}{*}{\begin{tabular}{} \end{tabular} } \\  & & Night(+) & & & & & & & \\  & Te Night & & & & & (+) & & Day (+) & \\ \hline \hline \multirow{3}{*}{15-10-2015} & \multirow{3}{*}{9-12 (+)} & \multirow{3}{*}{8-12 (+)} & \multirow{3}{*}{-} & (+) Ne & & & & (+) Ne & \multirow{3}{*}{\begin{tabular}{} \end{tabular} } \\  & & Night(-) & & & & & & (-) Ne & \\ \hline \hline \multirow{3}{*}{17-10-2015} & \multirow{3}{*}{8-19 (+)} & \multirow{3}{*}{6-9 (+)} & \multirow{3}{*}{\
\begin{tabular}{} \end{tabular} } & & & 20, 21 (NE & & (+) Ne & \multirow{3}{*}{
\begin{tabular}{} \end{tabular} } \\  & & Day(-) & & & & & & \\  & Night (-) & & & & & & & (-) Ne & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Common anomalies prior to the October 2015 earthquake; DOE is day of earthquake.  
12:30 UTC, and those on 11 October appeared from 3 to 14 UTC. Also, for 15 October, the anomalies for the third earthquake event appeared at 3-14 UTC on 13 October; those on 14 October appeared at 2-12 UTC; and finally, on the last earthquake day, the anomalies kept on appearing in the same time range as the previous pattern: from 7 to 15 October at 3-12 UTC. The anomalies that appeared were well synchronized with the anomalies appearing in the GIM-TEC and Te and Ne observations; for reference, see Tables 1 and 2. To support this statement, it can be seen in Table 1 that the GPS-TEC anomalies appeared almost 11 days before the earthquake day, and the time and durations coincided with the GIM-TEC anomalies; e.g., for the GIM-TEC anomalies, the appearance time was around 9-12 UTC, and the GPS-TEC anomalies appeared from 8 to 12 UTC for the 2015 earthquake cases. Similar coinciding time duration can be seen on the other excluded days and for the 2023 earthquake cases as well.