A new seismic source model for the Egyptian territory and its surroundings is proposed. This model can be readily used for seismic hazard assessment and seismic forecasting studies. The definition of this model includes not only the seismicity data but incorporates all available geological and geophysical data, in an attempt to define areas which show not only a homogeneous seismicity release, but also exhibit similar seismic and seismotectonic characteristics. For this reason, an updated and unified earthquake catalogue (2200 B.C.- 2013), was compiled and employed in the current study. Data were obtained from different sources, local, regional and international (e.g., the regional catalogue of Ambraseys et al., 1994; the International Seismological Center (ISC) and the annual bulletin of the Egyptian National Seismological Network). The initial compilation spanning a region from 21° to 38°N and from 22° to 38°E, and includes all the events having an assigned magnitude of 3.0 and above for international sources and any magnitude value for local sources on any magnitude scale. Earthquake magnitudes are reported in different scales and come from a variety of sources. For establishing a common magnitude, namely an equivalent moment magnitude (MW), two new relationships correlating surface-wave (MS) and body-wave (mb) magnitudes with MW were specifically derived. All non-Poissonian (dependent) events were removed using the Gardner and Knopoff (1974) approach. A total of 16642 events represent the final Poissonian catalogue with a magnitude above or equal to MW 3.0. The proposed seismic source model comprises 28 seismic sources including the shallow seismicity (h ≤ 35 km) for the Egyptian territory and its surroundings. In addition, for the Mediterranean region, we proposed the shallow seismic source zones (h ≤ 20 km), used in the SHARE (2013) project for estimating the seismic hazard for Europe. Furthermore, to cover the intermediate-depth seismicity (20 ≤ h ≤ 100 km), 7 intermediate-depth seismic source zones have been delineated in the Eastern Mediterranean region. Following the determination of zone boundaries, a separate earthquake and focal mechanism sub-catalogue for each seismic zone was created. Several seismicity parameters (b-value, activity rate and maximum expected magnitude) have been computed for each source. In addition, the predominant focal mechanism solution was assigned in each source zone using the stress field inversion approach. This characterization of the seismic sources represents the main input for the seismic hazard assessment studies.

A new seismic source model for the Egyptian territory and its surroundings is proposed. This model can be readily used for seismic hazard assessment and seismic forecasting studies. The definition of this model includes not only the seismicity data but incorporates all available geological and geophysical data, in an attempt to define areas which show not only a homogeneous seismicity release, but also exhibit similar seismic and seismotectonic characteristics. For this reason, an updated and unified earthquake catalogue (2200 B.C.- 2013), was compiled and employed in the current study. Data were obtained from different sources, local, regional and international (e.g., the regional catalogue of Ambraseys et al., 1994; the International Seismological Center (ISC) and the annual bulletin of the Egyptian National Seismological Network). The initial compilation spanning a region from 21° to 38°N and from 22° to 38°E, and includes all the events having an assigned magnitude of 3.0 and above for international sources and any magnitude value for local sources on any magnitude scale. Earthquake magnitudes are reported in different scales and come from a variety of sources. For establishing a common magnitude, namely an equivalent moment magnitude (MW), two new relationships correlating surface-wave (MS) and body-wave (mb) magnitudes with MW were specifically derived. All non-Poissonian (dependent) events were removed using the Gardner and Knopoff (1974) approach. A total of 16642 events represent the final Poissonian catalogue with a magnitude above or equal to MW 3.0. The proposed seismic source model comprises 28 seismic sources including the shallow seismicity (h ≤ 35 km) for the Egyptian territory and its surroundings. In addition, for the Mediterranean region, we proposed the shallow seismic source zones (h ≤ 20 km), used in the SHARE (2013) project for estimating the seismic hazard for Europe. Furthermore, to cover the intermediate-depth seismicity (20 ≤ h ≤ 100 km), 7 intermediate-depth seismic source zones have been delineated in the Eastern Mediterranean region. Following the determination of zone boundaries, a separate earthquake and focal mechanism sub-catalogue for each seismic zone was created. Several seismicity parameters (b-value, activity rate and maximum expected magnitude) have been computed for each source. In addition, the predominant focal mechanism solution was assigned in each source zone using the stress field inversion approach. This characterization of the seismic sources represents the main input for the seismic hazard assessment studies.

Seismic hazard in terms of mean peak ground acceleration (PGA) and spectral acceleration (SA) values has been computed for Egypt using both historical and instrumental earthquake data. In order to carry out this appraisal, a typical zoning method using the CRISIS software was employed. For this purpose, an updated earthquake catalog, spanning the time period from 2200 B.C. to 2013, has been compiled for Egypt and its surrounding regions, and prepared to be used in a new probabilistic seismic hazard assessment. The earthquakes sizes were unified in terms of the moment magnitude scale and the catalog was declustered. A new seismic source model, for the seismic activity in and around Egypt, consisting of a total of 88 seismic zones (for shallow- and intermediate-depth seismicity) was considered in this new assessment. The seismic parameters have been specifically computed for 35 seismic sources covering the Egyptian territory and the Eastern Mediterranean region. A logic-tree design was setup in order to consider the epistemic uncertainty in the Gutenberg-Richter b-value, maximum expected magnitude (Mmax) and the selected ground-motion prediction equations (GMPEs). Computations: Seismic hazard computations, for rock-site conditions, with 10% and 5% probability of exceedance in 50 years have been carried out. In addition, uniform hazard spectra for twelve, among the most important and populated cities in Egypt, are computed and compared with the most recent Egyptian building code values. Then, the seismic hazard deaggregation results for the most important cities has been performed in terms of distance and magnitude, to help understanding the relative contributions of the different seismic sources. Seismic hazard deaggregation, in particular, was computed for spectral acceleration at periods of 0.0, 0.2, 1.0 and 2.0 s for rock-site conditions, for 10% probability of exceedance in 50 years. It is interesting to highlight that the maximum hazard values are observed at the Gulf of Aqaba region, specifically around the epicentral location of the biggest Egyptian recorded earthquake of 22 November 1995 (MW 7.2) Aqaba earthquake. The obtained seismic hazard values for Nuweiba city (located in this region), for PGA and SA (0.1-s) are 0.29 g and 0.74 g, respectively, for a return period of 475 years. Moreover, the deaggregation results indicate that distance to the seismic sources which mostly contributes to the seismic hazard is mainly controlled by the nearby sources. However, distant events contribute more to the hazard for larger spectral periods (for 1.0 and 2.0 s). A significant result of this type of works is that seismic hazard deaggregation provides useful data on the distance and magnitude of the contributing seismic sources to the hazard in a certain place, which can be applied to generate scenario earthquakes and select acceleration records for seismic design.

Probabilistic seismic hazard analysis in terms of peak ground acceleration (PGA) and spectral acceleration (SA) values was assessed for the Egyptian territory. Eighty-eight potential seismic sources (for shallow- and intermediate-depth seismicity) in and around Egypt were identified and characterized based on an updated and unified earthquake catalogue spanning the time period from 2200 B.C. until 2013. Earthquake recurrence rates were computed, from both instrumental and historical data, for the defined seismic sources. Six well-known ground-motion attenuation models were selected to predict the ground motion for the different tectonic environments in and around Egypt. Finally, a logic-tree approach was followed, after a sensitivity analysis, to consider the epistemic uncertainty in different inputs (b-value, maximum expected magnitude and ground-motion attenuation model). In the present study, we show the seismic hazard deaggregation results, in terms of distance and magnitude, for the most important cities in Egypt to help understanding the relative contributions of the different seismic sources. Seismic hazard deaggregation for PGA, 0.2, 1.0 and 2.0 s SA, for 10% probability of exceedance in 50 years (return period of 475 years), was computed in detail. The deaggregation graphs were drawn considering bins of 0.5 for magnitude and 25 km for distance. The mean and modal values of magnitude and distance, to identify the distribution of control earthquakes that contribute to exceedance of the considered SA level were also computed. In general, the results at most of the cities, indicate that the distance to the seismic sources which mostly contributes to the seismic hazard is mainly controlled by the nearby seismic sources (especially for PGA). However, the more distant events contribute more to the hazard for larger spectral periods (for 1.0 and 2.0 s SA). For instance, the control earthquake for Cairo has a moment magnitude (MW) values in the range 5.0-5.5 and a focal distance between 0 and 25 km for PGA, 0.2, and 1.0 s SA, whereas for 2.0 s the distance remains the same but the magnitude become 6.0-6.5. However, for Port Said (located along the Mediterranean Sea coast), values of 7.0-7.5 MW and 375-400 km for the control earthquake has been obtained for all spectral periods. A significant result of this type of work is that seismic hazard deaggregation provides useful data on the distance and magnitude of the contributing seismic sources to the hazard in a certain place, which can be applied to generate scenario earthquakes and select acceleration records for seismic design.

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The u.v.-visible electronic spectra of 4-arylidene-1-(2, 4-dinitrophenyl)-3-methyl-2-pyrazolin-5-ones (1a-f) have been studied. The different bands observed have been assigned to the proper electronic transition. Solvatochromic behaviour of these compounds is investigated by studying their visible spectra in organic solvents of different polarity. The longer wavelength band displayed by the hydroxy derivatives is assigned to an intermolecular CT transition. The H-bonding solvated complexes formed between ethanol or DMF and p-hydroxy substituted derivative are investigated. Transition moment (CT), G and Kf values of these complexes have been determined.