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The present-day stress field in Egypt has been investigated on the basis of updated earthquake focal mechanism catalog covering the period from 1951 to 2017. Our catalog contains 234 focal mechanisms compiled from previous studies in addition to 22 new source mechanism solutions achieved in this study. According to the distribution of the recent earthquake epicentres, Egypt is divided into nine seismotectonic regions. The available fault plane solutions in Egypt demonstrate a spatial variability of source mechanisms, which categorize the study area into three groups. The first group includes Dahshour, Beni Suef, Cairo-Suez district, Northern-Central Gulf of Suez and Southern Gulf of Suez, which characterized by pure normal faulting mechanism to normal faulting with strike-slip component. Pure strike-slip faulting has clearly characterised Aswan and Gulf of Aqaba regions in the second group. However, the third group, which contains Abu Dabbab and the northern Egyptian continental margin, is characterized by thrust and strike-slip faulting. To calculate the orientation of the principle stress axes and the shape ratio we have applied the stress inversion technique. The present-day stress regime shows a variability of the tectonic stresses including extensional tectonic, transtensional and strike-slip. The transtensional stress regime with a maximum horizontal extensional NNE stress axis represents the dominant stress field pattern in Egypt. The results exhibit a good agreement with the tectonic settings and recent deformations in Egypt. [ABSTRACT FROM AUTHOR]

On 27 June 2015, a moderate earthquake with magnitude Mb 5.2 struck the Gulf of Aqaba near Nuweiba City. This event was instrumentally recorded by the Egyptian National Seismic Network (ENSN) and many other international seismological centres. The event was felt in all the cities on the Gulf of Aqaba, as well as Suez City, Hurghada City, the greater Cairo Metropolitan Area, Israel, Jordan and the north-western part of Saudi Arabia. No casualties were reported, however. Approximately 95 aftershocks with magnitudes ranging from 0.7 to 4.2 were recorded by the ENSN following the mainshock. In the present study, the source characteristics of both the mainshock and the aftershocks were estimated using the near-source waveform data recorded by the very broadband stations of the ENSN, and these were validated by the P-wave polarity data from short period stations. Our analysis reveals that an estimated seismic moment of 0.762 × 10 Nm was released, corresponding to a magnitude of Mw 5.2, a focal depth of 14 km, a fault radius of 0.72 km and a rupture area of approximately 1.65 km. Monitoring the sequence of aftershocks reveals that they form a cluster around the mainshock and migrated downwards in focal depth towards the west. We compared the results we obtained with the published results from the international seismological centres. Our results are more realistic and accurate, in particular with respect to the epicenteral location, magnitude and fault plane solution which are in accordance with the hypocentre distribution of the aftershocks. [ABSTRACT FROM AUTHOR]