One-dimensional P-wave velocity structure in the northern Red Sea area, deduced from travel time data

Abstract

Travel time inversion of local earthquake data was used to improve a one-dimensional (1-D) P-wave velocity structure model for the northern Red Sea area, including the entrance of the Gulf of Suez and the Gulf of Aqaba. The 1-D velocity model and station corrections were obtained by using 1538 P-arrivals from 216 well-located earthquakes recorded at ten local seismic stations from August 1994 to January 1999. Earthquakes used in the present study were located in depths less than 28 km so that the upper 20 km of the 1-D velocity model was well constrained. The resulting P-velocity model indicated velocities from 5.0 to 6.0 km/sec down to a depth of 10 km, and velocities from 6.0 to 6.8 km/sec with a nearly constant gradient in a depth range from 10 to 20 km. This 1-D velocity model reduced the RMS residual by 47% from 0.21 to 0.11 sec and improved routine earthquake locations, which clearly indicated clusters of hypocenters in the southern tip of the Sinai Peninsula and the entrance of the Gulf of Suez. The resulting station corrections suggested irregular surface geology in the area. Negative and positive station corrections were obtained; the minimum value (−0.35) was observed at the station MAZR, while the maximum value (0.24) at SHRM.