# Seismic and Geodetic Crustal Moment-Rates Comparison: New Insights on the Seismic Hazard of Egypt
## 3 Preparation of an Updated and Unified Earthquake Catalog
Duplicated earthquakes were identified, based on their geographic location and the date and time of their occurrence, and removed from the compiled dataset. In order to unify the different magnitude scale of the catalog into the moment magnitude one, the following magnitude-scaling relationships have been used:  
* For those earthquakes compiled by [PERSON] et al. (2018), ISC, EHB-ISC, and USGS bulletins, the same conversion relationships developed by these authors have been applied to convert macroseismic intensity values, mb, Ms, MD, and ML to Mw (Equations (1)-(5)). * For those events gathered from [PERSON] et al. (2018) catalog for the Arabian Peninsula, the relationships by [PERSON] et al. (2018) for developing a unified earthquake catalog for the surroundings of the United Arab Emirates were used, by converting the mb, Ms, and ML magnitudes to Mw (Equations (6)-(8)). * Finally, since the data collected from the Israel National Seismic Network are reported in MD scale, the conversion relationship developed by [PERSON] et al. (2018) to do the conversion to the Mw scale has been used (Equation (9)). \[M_{w}=\frac{2}{3}\Big{(}19.36+0.48\cdot I_{\text{max}}+0.0244\cdot I_{\text{ max}}^{2}\Big{)}-10.70 \tag{1}\]  
\[M_{w}=-1.31+1.26\cdot m_{b} \tag{2}\]  
\[M_{w}=3.97-0.13\cdot M_{s}+0.08\cdot M_{s}^{2} \tag{3}\]  
\[M_{w}=\frac{2}{3}(1.35\cdot ML+16.30)-10.70 \tag{4}\]  
\[M_{w}=\frac{2}{3}(1.45\cdot MD+16.30)-10.70 \tag{5}\]  
\[M_{w}=0.61\cdot M_{s}+2.31 \tag{6}\]  
\[M_{w}=1.03\cdot m_{b}-0.06 \tag{7}\]  
\[M_{w}=0.76\cdot ML+1.36 \tag{8}\]  
\[M_{w}=\frac{2}{3}\Big{(}0.19\cdot MD^{2}-0.20\cdot MD+12.27\Big{)}-6.0 \tag{9}\]  
In a successive step, to properly estimate the seismicity parameters (activity rate, \(b\)-value, and maximum expected magnitude), a declustering process of the catalog was performed. This step allows erasing of earthquake swarms and sequences which generally affect the activity rate and \(b\)-value estimations from the catalog. In this regard, the procedure by [PERSON] (1970) has been applied. Given a certain magnitude, a scan within defined distance and time windows was performed for the whole unified catalog. Throughout this inspection, an earthquake having the largest magnitude is considered the mainshock or the independent one. Distance and time windows of 36 and 100 km and 100 and 600 days were applied for earthquakes with magnitudes Mw 4.0 and 8.0, respectively (1998). As a result, a final catalog with 3.419 earthquakes was obtained covering the geographic region between 21\({}^{\circ}\) and 34\({}^{\circ}\) N latitudes, and between 24\({}^{\circ}\) and 38\({}^{\circ}\) E longitudes, and within the period from 2200 B.C. to 2020, including both historical and instrumental earthquakes. The completeness periods were estimated for the entire catalog. This was done by plotting the cumulative number of earthquakes for specific magnitude ranges against time (Figure 2). From the completeness analysis (Table 1), it was found that the catalog is complete for magnitudes above Mw 3.0, 4.0, 5.0, 6.0, and 7.0 broadly since the years 1995, 1980, 1925, 700 A.D., and 240 A.D., respectively. Some of the obtained completeness periods are closely related to the establishment or the improvement of some local and international networks. For instance, the years 1900, 1960, 1983, and 1993 are the approximates dates for the establishment of the Helwan Observatory in Cairo, the deployment of the World-Wide Standardized Seismograph Network (WWSSN), the installation of the Aswan Seismological Network around Nasser's Lake, and the installation of the Egyptian National Seismic Network in Egypt after 12 October 1992, Mw 5.8 Cairo earthquake, respectively [55,56]. The given completeness periods for the current catalog indicate that our catalog is not as complete as could be desired. This is due mainly to the incomplete coverage of the seismic stations during the early instrumental period. Thus, some biases, underestimation, or overestimation for the seismicity parameters are expected during the computations.