Abstract The interpretation of aeromagnetic data, in the marine Hurghada-south Sinai, Red Sea area reveals a continental crust which is partially invaded by volcanics. This crust is apparently uninvolved in the Red Sea rifting. Correlation with onshore Dokhan Volcanics (Precambrian) of the Esh El Mellaha Range suggests that the origin of the observed anomalies is the susceptibility contrast between them and the granitic basement of Precambrian age. Magnetic data, aided by gravity and seismic reflection data, show that part of the basement beneath the Shadwan Island was involved in at least two faulting processes, namely that of the Red Sea (NW) and that of the left-lateral shear movement of the Aqaba-Dead Sea rift (NNE). A NNE trending magnetic anomaly, at the entrance of the Gulf of Aqaba, is interpreted as a rotated basement block due to the shear movement of the Aqaba-Dead Sea rift. It is shown that axes of the gravity maxima and minima are displaced and, in part, rotated in the proximity of the inferred, from magnetic data, trace of the Aqaba-Dead Sea rift.