Seismological observations in and around the southern part of the Gulf of Suez, Egypt

We have established a seismological network in the southern part of the Gul f of Suez, at the northern end of the Red Sea, in Egypt. The network consis ts of 10 satellite stations: five in the southern tip of the Sinai Peninsul a, four on the African continent, and one on Shadwan Island, where a M-s 6. 6 earthquake occurred in March 1969. The first six stations were installed in August 1994, and the remaining four were added by June 1996. All data ar e radio transmitted to a central station in the city of Hurghada. Each stat ion consists of one 1-Hz vertical-component seismograph except for one thre e-component station. We use the IASPEI Software Library for data acquisitio n and analysis. Seismic data are AID converted into 12-bit, sampled at 100 Hz, and stored in desktop computers. Almost all earthquakes occurred at the center of the Gulf of Suez, the cent er of the northern end of the Red Sea, and the Gulf of Aqaba, where old and new plate boundaries exist between the African and Arabian plates. Three s eismic zones are clearly observed along these boundaries. Three dominant ea rthquake swarms were also observed at the entrance of the Gulf of Suez. The focal depths of almost all earthquakes observed in the network range mainl y from 5 to 20 km. The focal mechanisms of earthquakes show a variety of pa tterns. The most predominant type is normal faulting along the NE-SW tensio nal axes; this is consistent with the mechanism of the 1969 earthquake and the opening of the Red Sea and the Gulf of Suez.