Earthquake recurrence estimation of Dahshour area, Cairo, Egypt, using earthquake and GPS data

On Oct. 12, 1992, Cairo was shocked by an earthquake with a moment magnitude Mw = 5.8. It is considered the most severe earthquake that hit Egypt in the twentieth century. It caused damage, deaths, and home collapses. Recently, mega-projects associated with public infrastructures are running around Cairo. Therefore, considering such seismic activity and related ground deformation is vital for the sustainability of these projects. The estimation of such an earthquake's recurrence rate is very important for future seismic hazard and seismic risk assessments. Here, we use 11 years of GPS data (epoch and permanent sites) to map the ground motion of the area west of Cairo (Dahshour seismic source). In addition to GPS data, an earthquake catalog considering historical and instrumental seismicity records is used to calculate the recurrence rate of the 1992 Cairo earthquake. The earthquake catalog is processed through magnitude unifying, de-clustering, and performing completeness analysis. In the Nubia fixed frame, GPS sites show a systematic trend of the north-to-northeastward motion. A slip rate of 1.4 ± 0.4 mm/year along the fault is estimated. Based on the estimated slip rate obtained from GPS and seismicity analysis, an average recurrence frequency for the Cairo earthquake of 107–116 years is estimated.