Results from three refraction profiles in the northern Red Sea (above 25°N) recorded with an Ocean Bottom Vertical Seismic Array

We present here results of three refraction profiles obtained during the “Minos” cruise (March–April, 1986) in the northern Red Sea (above 25°N) with our new marine seismic observation system, the Ocean Bottom Vertical Seismic Array (OBVSA). In the first part of the paper, we briefly describe the instrument and give some of its main characteristics. In the second part, we present a velocity-depth model for each one of the three non-reversed profiles. The model is first inferred from interpretation of the hodochron, using the slope intercept method and assuming plane interfaces, and iteratively modified by application of a ray tracing program. Our results support other data collected durng the cruise with Expanding Spread Profiles and reported elsewhere in this issue by Gaulier et al. (1988). The two northern profiles are about 50 km long and are oriented N15 °E. The recording instrument was located at the southern extremity of the profiles at 26°35′N, 34°46′E and 27°00′N, 34° 26′E respectively. The basement velocity was found to be in the 5.2–5.8 km s −1 range. The Moho is located at about 14 km below the sea level. The upper mantle apparent velocity is about 7.3 km s −1 . The southern profile is 40 km long, oriented S45° W with the OBVSA located at its eastern extremity, at 26°06'N, 35°23′E. The Moho depth is about 11.5 km. The crustal structure under the eastern part of the profile is interpreted as being of the oceanic type.