## 4 Case Analysis  
The first \(M\geq 6.7\) earthquake, which occurs inside or at the margin of the spatial location of a seismic gap right after the end of the gap, is defined as the earthquake corresponding to the gap. Table 1 lists the characteristic parameters of the spatio-temporal images of the six seismic gaps and the corresponding \(M\geq 6.7\) earthquakes. Figure 6 shows the spatial distributions of the gaps and those of their corresponding earthquakes. According to Table 1 and Figure 6, after each seismic gap ended, \(M\geq 6.7\) earthquakes occurred either inside or at the margin of its spatial location. The correspondence rate is 100%. More specifically, five earthquakes took place within the spatial location of the gap (83%) while one was at the margin (17%). The quiet periods of the six seismic gaps are 419-777 days (about 14-26 months), with an average of 580 days (19 months approximately). The major-semi-axis and semi-minor-axis lengths of the gaps are in the 880-1050 km (approximately 987 km on average) and 500-570 km (about 533 km on average) ranges, respectively. The interval times between the ends of the gaps and the corresponding earthquakes are 0-776 days (about 0-26 months), with an average of 395 days (13 months). Figure 5: Combined \(M\geq 4.0\) earthquake intervals of the six seismic gaps. Green solid line: No. 1 seismic gap; Red solid line: No. 2 seismic gap; Blue solid line: No. 3 seismic gap. Green dotted line: No. 4 seismic gap; Red dotted line: No. 5 seismic gap; Blue dotted line: No. 6 seismic gap. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Earthquake ID** & **Quiet Period T1** & **Semi-Major-Axis** & **Earthquakes Marking the Beginning** & **Congerding Earthquake** & **Quiet Period T2** \\
**(Day/Month)** & **Length/Semi-Minor-Axis** & **Length (km)** & **and End of the Seismic Gap** & **(Day/Month)** \\ \hline No. 1 & 517/17 & 960/570 & 8 November 1970\(-\)M5.5 earthquake in Kanho on & 47.6 earthquake in Kanho on & 302/10 \\  & & & Kangling on 8.8 April 1972 & 6 February 1973 & 302/10 \\ \hline No. 2 & 514/17 & 1030/550 & 13 August 1986\(-\)M5.5 earthquake in Kanho on 1 January 1988 & & \\  & & & Ninglang on 10 January 1988 & & \\ \hline No. 3 & 777/26 & 1050/540 & 17 December 1993\(-\)M7.0 earthquake in Ljänga on & 47.0 earthquake in Ljänga on & 0/0 \\  & & Ljänga on 3 February 1996 & 3 February 1996 & & \\ \hline No. 4 & 419/14 & 990/500 & 13 July 2007 & 47.1 earthquake in Yushu on & 586/20 \\  & & & \(\sim\)M4.2 earthquake in Ganai on & 14 April 2010 & \\  & & & \(\sim\)M4.6 earthquake in Shangri-La on & 46.9 earthquake in Millin on & 776/26 \\  & & & \(\sim\)M2005 & 18 November 2017 & 776/26 \\  & & & \(\sim\)M4.2 earthquake in Lathuo on 3 June & 46.8 earthquake in Lading & 246/8 \\  & & & \(\sim\)2 January 2022 & & 395/13 \\ \hline \hline Average & 580/19 & 987/533 & & & \\ \hline \end{tabular}
\end{table} 
Table 1: Characteristic parameters of the spatio-temporal images of the six seismic gaps and the corresponding \(M\geq 67\) earthquakes. Apart from that of the No. 5 gap, the corresponding earthquakes of the other five seismic gaps (No. 1-4 and No. 6) all occurred within the spatial location of the gaps. They were concentrated at the boundary of the western Sichuan block, namely the Xianshuihe fault zone and the Jinshajiang fault zone. A total of seven \(M\geq 6.7\) earthquakes (earthquake episodes) occurred within the western Sichuan block or at its boundary in 1970-2022, whereas \(M\geq 4.0\) seismic gap images are noted before five of the earthquakes (earthquake episodes) (71%). The results demonstrate that the occurrence of \(M\geq 4.0\) seismic gap images in the region is always followed by that of \(M\geq 6.7\) earthquakes, with a correspondence rate of 100%. Meanwhile, the occurrence of \(M\geq 4.0\) seismic gap images before that of \(M\geq 6.7\) earthquakes is 71%. Hence, more attention should be placed on the \(M\geq 4.0\) seismic gap images in the region because they may be of high predictive significance.