Seismic Design Criteria For The South SinaiRed Sea Rift Zone

Abstract

The Red Sea rift zone is an area of medium to high seismic hazard, with many medium and large magnitude earthquake recorded historically and very recently. On the other hand, the shoreline in South Sinai and on the Egyptian mainland has undergone unprecedented development with tens of new mini-towns and tourist resorts. Detailed and verified seismic design criteria and sample input motion have not been derived before this important area. In this paper, all available historical and instrumental records of earthquake activity are reviewed, and a definitive catalogue assembled. Conventional probabilistic seismic hazard analysis was undertaken, whilst ensuring the homogeneity of the data used. Levels of ground motion for seismic design are derived as a function of probability of being exceeded, and for different return periods. It is concluded that a level of PGA of about 0.175g (rock-stiff sites) is a conservative value recommended for design. Contrary to the recommendations of the Egyptian seismic code, the levels of excitation for low-rise structures is significant and should not be ignored. Moreover, the possible deterministic earthquake scenarios for the area are discussed. These are used to select recorded ground-motion accelerations from seismotectonic environments similar to the South Sinai area. The average spectra from the selected suite of records is compared to the EC8 spectral model, and shown to be reasonable, though well below EC8 in the long period range. The conclusions and recommendations of this paper are an important contribution to the study of seismic hazard and risk in an area not elaborately studied before and is of interest to both practitioners and researches who are concerned with earthquake issues in this part of the Middle East.