# Seismic and Geodetic Crustal Moment-Rates Comparison: New Insights on the Seismic Hazard of Egypt
## 4 Seismicity of Egypt  
Egypt is characterized by earthquakes of moderate magnitudes which mainly concentrate along the surrounding plate boundaries (the Gulf of Aqaba-Dead Sea transform fault, the Gulf of Suez-Red Sea rift, and the Nubian-Eurasian plate boundary). Available publications and catalogs of historical (pre-1900) earthquakes in Egypt [48,57,58,59,60] document the occurrence of only 83 earthquakes in the Egyptian lands (Figure 3). In addition, the population concentration along the Nile River and its delta creates imprecision in the proper identification of the location and the possible damage effects of historical earthquakes. In Figure 3, the historical earthquakes that occurred in and around Egypt have been imported mainly from [PERSON] et al. [48] earthquake catalog and were plotted in terms of the computed equivalent moment magnitude using the relationships shown above. They documented the occurrence of about 230 earthquakes in and around Egypt within the period between 2200 B.C. and 1899 A.D., and within the intensity range of III to XI (MMI Scale) [48]. On the other hand, regarding the instrumental events (1900-2020) (Figure 4), Egypt shows relatively moderate seismicity in comparison to other regions all over the world. However, it was affected by some damaging large earthquakes that originated mainly along the Hellenic and the Cyprian Arcs, as well as those from Southern Palestine [59]. The following points can be deduced from the plotting of seismicity: (a) a higher concentration for the instrumental seismicity appears on the northeastern parts of Egypt, especially along the triple junction of the Gulf of Suez, the Gulf of Aqaba and the Red Sea than those in southern Egypt, (b) the shallow seismic activity is mainly focused in the surrounding plate boundaries (the Gulf of Aqaba-Dead Sea fault system and the Gulf of Suez-Red Sea rift towards the east, and the Nubia-Eurasia plate boundary \"the Hellenic and the Cyprian Arcs\" towards the north) as well as on other active seismic zones (southwest \begin{table}
\begin{tabular}{c c c} \hline \hline
**Magnitude** & **Completeness Period** & **Activity Rate (Events/Year)** \\ \hline Mw \(\geq\) 3.0 & 1995–2012 & 111.0 \\ Mw \(\geq\) 3.5 & 1990–2012 & 26.2 \\ Mw \(\geq\) 4.0 & 1980–2020 & 11.0 \\ Mw \(\geq\) 4.5 & 1980–2020 & 4.14 \\ Mw \(\geq\) 5.0 & 1925–2020 & 0.909 (1 EQ by year) \\ Mw \(\geq\) 5.5 & 1900–2020 & 0.249 (1 EQ every 4 years) \\ Mw \(\geq\) 6.0 & 700–2020 & 0.0273 (1 EQ every 35–40 years) \\ Mw \(\geq\) 6.5 & 700–2020 & 0.00956 (1 EQ every \(\sim\)100 years) \\ Mw \(\geq\) 7.0 & 240–2020 & 0.00417 (1 EQ every \(\sim\)240 years) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Completeness periods and their corresponding activity rates for the current unified and declustered catalog. See Figure 2.  
Cairo, Cairo-Suez area, Abu Dabbab area on the Eastern Desert, offshore Delta region, west of Assiut and Sohag, and the surrounding of Nasser's Lake), and (c) little dispersed seismicity could be noticed along the Western Desert of Egypt or on the southern parts of the Eastern Desert. Examples of those large earthquakes that affected Egypt through previous decades are the 12 November 1955 (Mw 5.5) Abu-Dabbab, the 31 March 1969 (Ms 6.9) Shedwan, the 14 November 1981 (Mw 5.8) Aswan, the 12 October 1992 (Mw 5.8) Cairo \"Dahshour\", the 22 November 1995 (Mw 7.2) Gulf of Aqaba, and the 28 May 1998 (Mw 5.5) Ras El-Hikma earthquakes [48]. A recent database of focal mechanism solutions (1951-2019) has been provided in [PERSON] et al. [61]. These focal mechanism solutions (Figure 5) have been used to study the seismotectonics pattern of the investigated region as well as to define and delimitate the studied seismic sources. Differentiation of the different faulting mechanisms based on their rake angle was considered (Figure 5), i.e., pure normal-faulting  
Figure 2: Completeness analysis for the updated and declustered catalog. Completeness rates are also depicted.