Assessment of seismic hazards for Hurghada, Red Sea, Egypt

The entrance of the southern Suez Gulf of the Red Sea is known to be an area of high seismic activity in Egypt. The high rate of seismic activity in this area is mainly related to the adjustment in motion at the triple junction between the African plate, the Arabian plate, and the Sinai microplate. The present study attempts to estimate the Probabilistic Seismic Hazard Analysis (PSHA) for Hurghada site. This was done in two steps; the first one is by estimating specific parameters for the site, such as the mean seismic activity, lambda, the Gutenberg-Richter parameter, b, and the maximum regional magnitude, m (max). The second step is by selecting a ground motion parameter that is applicable to Hurghada site. The procedure permits the combination of both historical and recent instrumental data. The results of the hazard assessment, expressed as the worst case scenario, detect that Hurghada is exposed to the maximum credible earthquake event of magnitude m (max) = 7.1 +/- A 0.31, at hypocentral distance of 31.6 +/- A 10 km. The possibility of the maximum Peak Ground Acceleration (PGA), which occurred in relation to this event at Hurghada site, is equal to 0.29 g. The mean return periods with the selected accelerations for Hurghada, a horizontal acceleration of 0.1 g, is expected to occur once every 74-106 years, with an average of one every 90 years. This result which obtained from the hazard assessment can be used as an input data for a seismic risk assessment.