## 3 Results
### FCAZ Recognition of the Strongest Earthquake-Prone Areas
The above statistical data allows, to a great extent of reliability, interpreting FCAZ zones (Figure 9) as the areas prone to strong earthquakes in California and the areas prone to significant earthquakes in the Altai-Sayan region, the Caucasus, as well as in the Crimean Peninsula and the northwestern Caucas. The description of the first-ever successive recognition of the areas prone to earthquakes for several magnitude thresholds in the same region is given further. This recognition was performed using the SFCAZ method mentioned above, which further develops FCAZ. Successively studied were the areas prone to earthquakes with \(M\geq 5.5\), \(M\geq 5.75\), and \(M\geq 6.0\) in the Baikal-Transbaikal region [35]. Phase one of the research entailed the solution of a classical problem of recognizing the areas prone to significant earthquakes (\(M\geq M_{0}=5.5\)). Figure 10a shows the recognized zones that are well aligned with the earthquake epicenters with \(M\geq 5.5\). Out of 71 such earthquakes, the epicenters of two (2.8%) are located outside of recognized zones, thus creating missed target errors. These two earthquakes occurred before the commencement of active instrumental observations in the region (1929 and 1957) and have a magnitude \(M=5.6\), identified to a precision of \(\pm 0.5\)[52], and their epicenters are located outside of the Russian Federation. Accordingly, their actual magnitude can be lower than the threshold \(M_{0}=5.5\) and the completed recognition is likely to have no missed targets. Totally new are the second and third phases of successive recognition. Phase two entailed studying the areas prone to significant earthquakes with \(M\geq 5.75\) in the same Baikal-Transbaikal region. To that end, only the epicenters that were included in DPS clusters during phase one were used as recognition objects. Accordingly, inside the DPS clusters that define high seismicity zones for \(M\geq 5.5\), subclusters and morphogenetic areas prone to stronger significant earthquakes were recognized. The zones recognized in this way are well aligned with the earthquake epicenters with \(M\geq 5.75\) (Figure 10b). The epicenters of just 3 (10%) of 30 such significant earthquakes lie  
Figure 10: Baikal–Transbaikal region: (**a**) zones prone to earthquakes with \(M\geq 5.5\) and the epicenters of earthquakes with \(M\geq 5.5\); (**b**) zones prone to earthquakes with \(M\geq 5.75\) and the epicenters of earthquakes with \(M\geq 5.75\); (**c**) zones prone to earthquakes with \(M\geq 6.0\) and the epicenters of earthquakes with \(M\geq 6.0\). outside of their boundaries. These are the epicenters of earthquakes with a fairly inaccurate identification of magnitude: \(M\) = 5.8 \(\pm\) 0.5 and \(M\) = 5.8 \(\pm\) 0.2 [52]. The magnitude of the third earthquake was recalculated from the energy class. The magnitudes of these three earthquakes are highly likely to have the values of \(M\) < 5.75, and the earthquakes themselves are highly unlikely to constitute the subject matter of research. It should be noted that the recognized territories form part of high seismicity zones for the magnitude threshold \(M_{0}\) = 5.5, identified during phase one of the research. Phase three entailed recognizing the areas prone to strong earthquakes with \(M\geq 6.0\). The epicenters of earthquakes included in the DPS clusters during phase two have already been used as recognition objects. Out of 17 earthquakes with \(M\geq 6.0\), the epicenters of just two (11.7%) are located outside of recognized zones (Figure 10c). The first one is the epicenter of the 1939 earthquake with \(M\) = 6.0 \(\pm\) 0.3 [52]; the second one which occurred in 2008, with \(M\) = 6.3, is located at the distance of 0.15\({}^{\circ}\) of the mapped zones. After 2010, 3 earthquakes with \(M\geq 5.5\) occurred in the considered region. The epicenters of two of them lie strictly within the zones corresponding to their magnitudes, which is an argument in favor of the reliability of SFCAZ recognition results.