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 Gulf of Suez, at the northern end of the Red Sea, in Egypt. The network consists of 10 satellite stations: five in the southern tip of the Sinai Peninsula, 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 are radio transmitted to a central station in the city of Hurghada. Each station consists of one 1-Hz vertical-component seismograph except for one three-component station. We use the IASPEI Software Library for data acquisition 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 center 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 seismic zones are clearly observed along these boundaries. Three dominant earthquake swarms were also observed at the entrance of the Gulf of Suez. The focal depths of almost all earthquakes observed in the network range mainly from 5 to 20 km. The focal mechanisms of earthquakes show a variety of patterns. The most predominant type is normal faulting along the NE-SW tensional axes; this is consistent with the mechanism of the 1969 earthquake and the opening of the Red Sea and the Gulf of Suez.