Crustal velocity structure for Northern Egypt using ambient noise tomography

The northern Part of Egypt comprises the southeastern part of the Eastern Mediterranean region. This region is characterized by its complex tectonic setting and earthquake activity. The current study represents the first attempt to investigate the crustal structure of Northern Egypt using Ambient Noise Tomography (ANT), utilizing local seismological data acquired by the Egyptian National Seismological Network (ENSN) broadband stations and regional stations deployed in southern Europe. The current study utilizes one year of continuous raw data recorded by 32 broadband stations, with interstation distances of 50-1400 km. About 300 dispersion curves are selected from a total of 496 based on signal-to-noise ratio (SNR) and the standard deviation of seasonal measurements. The accepted measurements are inverted into group velocity maps representing periods between (5-25 s). The results show lateral variations in group velocities across the region. The crust in the Northern part of the Western Desert is characterized by low velocity. In contrast, higher velocities are observed in the Northern Eastern Desert and the Sinai Peninsula. The Moho depth is calculated for nine sites across the study area. The estimated Moho depth ranges between 31 and 42 km. A relatively shallow Moho depth of 31-32 km is observed close to the southern Coast of the Mediterranean Sea and increases to 37-42 km in the middle of the Western Desert. Beneath the Sinai Peninsula, the Moho is located at a depth of 33-35 km. The Conrad discontinuity is noted at a depth ranging between 10 and 16 km.