## 5 Statistical Characterization of Seismic Activity
### Progression of Earthquake Activity
#### 5.3.5 Local Variations and Concentrated Areas in Seismic Activity
Figure 10a,b present the Getis-Ord \(G^{\star}\) statistic maps for the 2008-2014 and 2014-2020 periods, respectively, in the Red Sea region. These maps visually represent seismic activity, with hotspots in various shades of red and coldspots in shades of blue,  
Figure 10: Spatial distribution of Getis-Ord \(G^{\star}\) clustering analysis and associated significance maps for the intervals 2008–2014 and 2014–2020. delineating a spectrum of earthquake activity from high \(Gi^{\bullet}\) to very low \(Gi^{\bullet}\). Accompanying these are the \(Gi^{\bullet}\) significance maps, which use a color gradient from dark green to yellow to indicate the statistical significance of these seismic patterns, thereby identifying areas where seismic clustering is not random. The distribution of high \(Gi^{\bullet}\) hotspots, predominantly along the Red Sea's axial trough, is consistent with the region's tectonic activity. This zone is an area of active rifting between the African and Arabian plates, characterized by seismic events associated with the formation of new oceanic crust and extensional tectonics. The concentration of seismic hotspots along this tectonic boundary points to their strong association with primary rifting processes, including seafloor spreading, faulting, and magmatic activity. In contrast, areas marked as low \(Gi^{\bullet}\) and very low \(Gi^{\bullet}\) are typically found on the flanks of the rift, indicating regions that are more stable and less affected by tectonic activity. The \(Gi^{\bullet}\) significance maps lend statistical credibility to these observations, affirming the spatial distribution of seismic hotspots and their significant alignment with the tectonic structure of the Red Sea rift system. These findings underscore the profound connection between seismic events and tectonic mechanisms in the Red Sea, exemplifying an active divergent plate boundary. Upon meticulous analysis of the results presented in Figures 7-10, a discernible systematic variation within a 26.7 to 27.7 latitude range was observed. This variation can be attributed to a confluence of factors. Primarily, it emerges from the differential seismicity reported across each distinct time period under consideration. These discrete temporal intervals exhibit unique patterns of seismic activity, significantly contributing to the variations observed. Additionally, the statistical framework underpinning the Local Indicators of Spatial Autocorrelation (LISA) method must be acknowledged. The method's statistical nature, as rigorously outlined in the significance figures for each period in each respective graph, plays an integral role in shaping these variations. The LISA methodology, with its focus on spatial autocorrelation, adeptly identifies regions characterized by significant spatial clustering or dispersion of seismic events. These variations are reflective of the intricate and dynamic interplay of spatial patterns in seismic activity across different time frames. These variations reflect the complex interplay of spatial patterns in seismic activity over time. A Kernel Density Estimator (KDE) [48; 65] is a robust statistical method for analyzing the spatial intensity of seismic events. This assists in identifying areas with higher earthquake frequencies, known as hotspots or local clusters. Figure 11 displays a series of KDE-derived clustered patterns, each corresponding to a different moment magnitude (\(M_{w}\)) range. Figure 11a-d present a sequential spatial analysis of seismic activity in the Red Sea region across increasing moment magnitude ranges. Starting from \(1.00\leq M_{w}<1.55\) in Figure 11a, the activity is primarily concentrated in the Gulf of Aqaba and Northern Red Sea, highlighting areas of potential tectonic or volcanic significance. This pattern persists and intensifies in the \(1.55\leq M_{w}<2.10\) range (Figure 11b), with notable clusters also in the southern Gulf of Suez.