Earthquake risk assessment of Alexandria, Egypt

Abstract

Throughout historical and recent times, Alexandria has suffered great damage due to earthquakes from both near- and far-field sources. Sometimes, the sources of such damages are not well known. During the twentieth century, the city was shaken by several earthquakes generated from inland dislocations (e.g., 29 Apr. 1974, 12 Oct. 1992, and 28 Dec. 1999) and the African continental margin (e.g., 12 Sept. 1955 and 28 May 1998). Therefore, this study estimates the earthquake ground shaking and the consequent impacts in Alexandria on the basis of two earthquake scenarios. The simulation results show that Alexandria affected by both earthquakes scenarios relatively in the same manner despite the number of casualties during the first scenario (inland dislocation) is twice larger than the second one (African continental margin). An expected percentage of 2.27 from Alexandria’s total constructions (12.9 millions, 2006 Census) will be affected, 0.19 % injuries and 0.01 % deaths of the total population (4.1 millions, 2006 Census) estimated by running the first scenario. The earthquake risk profile reveals that three districts (Al-Montazah, Al-Amriya, and Shark) lie in high seismic risks, two districts (Gharb and Wasat) are in moderate, and two districts (Al-Gomrok and Burg El-Arab) are in low seismic risk level. Moreover, the building damage estimations reflect that Al-Montazah is the highest vulnerable district whereas 73 % of expected damages were reported there. The undertaken analysis shows that the Alexandria urban area faces high risk. Informal areas and deteriorating buildings and infrastructure make the city particularly vulnerable to earthquake risks. For instance, more than 90 % of the estimated earthquake risks (buildings damages) are concentrated at the most densely populated (Al-Montazah, Al-Amriya, and Shark) districts. Moreover, about 75 % of casualties are in the same districts.