In this study, a seismogenic source zone model for the Algeria-Morocco region is proposed for seismic forecasting and seismic hazard studies. The delineation includes five zones based on available seismic and geological data. The zone model includes the Moroccan Meseta, the Rif, the Tell zone, the High Plateaux and the Atlas zone. Earthquake occurrence process in this region is modelled and analyzed using recent and updated earthquake catalogs for northern Morocco and northern Algeria compiled in former studies (Peláez et al. 2007; Hamdache et al. 2010). For these catalogues, dependent events were identified and removed by adapting Gardner and Knopoff declustering procedure to the characteristics of the study region. Magnitudes of completeness were estimated using different methods, then the Poissonian character of the obtained sub-catalogs was analyzed. The b-value of the Gutenberg-Richter recurrence relationship, considered as an area-specific seismic hazard parameter, was initially computed using the Weichert (1980) approach. In order to characterize each seismogenic zone we have used a new parameter named seismic activity, defined as the number of earthquakes with magnitude above Mw 4.0 in each seismogenic zone since 1925 by each 10 years and 10000 km2. The obtained results show for example, in the Tell zone, the seismic activity is equal to 2.6 and1.91 in the Rif region. The b-value estimation has been improved by using an extension of the Aki-Utsu bvalue estimator for incomplete earthquake catalogs (Kijko and Smit, 2012). Taking into account that the maximum possible magnitude is an important parameter required by earthquake engineering community, disaster management agencies and insurance industry, a detailed analysis has been performed using different statistical methods, free from subjective assumptions and only related to the quality of the earthquake data file. Thus, the maximum possible magnitude, using parametric and non-parametric procedures, is analyzed at each seismogenic zone and its probability distribution function is derived. Then, we derive the activity rate   m  for events above the magnitude m, the return period for different magnitudes and the probability of exceeding a magnitude m during a time period of T years. The analysis has been performed at each seismogenic zone of the proposed model.

A new and updated probabilistic seismic hazard assessment has been conducted for Egypt. To carry out this appraisal, new data and models has been incorporated, as well as a new treatment of the involved uncertainties in this type of studies. An updated and unified earthquake catalogue (2200 BC - 2013) has been compiled specifically for this assessment. A new seismic source model has been developed, including 28 shallow seismic zones (h 35 km) for the Egyptian territory and its surroundings, 53 shallow seismic sources (h 20 km) for the Eastern Mediterranean region after Seismic Hazard Harmonization in Europe (SHARE) project, and 7 intermediate seismic sources (20 h 100 km) covering the intermediate-depth seismicity in the Eastern Mediterranean region. These seismic sources were defined including all available data, some of them specifically compiled for this work (seismicity and focal mechanism catalogues). After a sensitivity analysis, a logic tree design was used in order to consider the epistemic uncertainty both in the b-value and the maximum expected magnitude of the Gutenberg-Richter recurrence relationship, as well as in the ground motion attenuation model. Using the CRISIS 2014 software, seismic hazard computations for rock site conditions and different return periods were performed. Here we show some of these results, in fact, peak horizontal ground acceleration (PGA) and spectral acceleration (SA) values for spectral periods of 0.2 and 1.0 s, and for return periods of 475 and 975 years. Moreover, uniform hazard spectra (UHS) have been computed specifically for some selected cities. All these results are compared with those included in the current Egyptian regulation. Maximum hazard values are obtained at Nuweiba city, located at the Gulf of Aqaba, around the location of the November 22, 1995, Mw 7.2 Aqaba earthquake. Values of 0.74 g and 0.98 g for a spectral period of 0.1 s, are obtained for return periods of 475 and 975 years, respectively. In Cairo, computed maximum values are 0.32 g and 0.44 g for the same return periods, also obtained for a spectral period of 0.1 s.

In this study, a seismogenic source zone model for the Algeria-Morocco region is proposed for seismic forecasting and seismic hazard studies. The delineation includes five zones based on available seismic and geological data. The zone model shown in figure 1, includes the Moroccan Meseta, the Rif, the Tell zone, the High Plateaux and the Atlas zone. Earthquake occurrence process in this region is modeled and analyzed using recent earthquake catalogs for northern Morocco and northern Algeria compiled in former studies (Peláez et al., 2007; Hamdache et al., 2010). For these catalogs, dependent events were identified and removed by adapting Gardner and Knopoff declustering procedure to the study region. Magnitudes of completeness were estimated using different methods, then the Poissonian character of the obtained sub-catalogs was analyzed. The b-value of the Gutenberg-Richter recurrence relationship, considered as an area-specific seismic hazard parameter, was initially computed using the Weichert (1980) approach.

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