Moho Depth and Crustal Velocity Structure Beneath Stations RTC and TAM from Teleseismic Receiver-Function Analysis
Eloumala Onana Parfait Noel, Iben Brahim Aomar, El Mouraouah Azelarab and Chabane Abdelkader
We apply the P-wave receiver-function technique to invert teleseismic data to investigate the S- wave
velocity structure beneath stations RTC and TAM in West Africa. Teleseismic waveform receiver function
analysis is a widely used technique for studying crustal structure beneath broadband seismic stations.
Our results show that the crust beneath RTC is relatively complex with large velocity fluctuations. In the
upper crust, a low velocity layer extends from 8 to 12 km deep. At Tamanrasset crustal structure east and
west of the station differ. We find a high-velocity zone between 2 and 8 km to the east that we attribute
to a high conductivity unit corresponding to intrusions described in the literature. We find no similar
feature west of the station. Our velocity models for RTC and TAM are consistent with their differing
tectonic environments. TAM, on a stable craton, displays a fairly homogeneous velocity structure while
RTC, on thick sediments in an ocean-continent transition zone, has more heterogeneous structure. This
structural difference is reflected as well by the depth to Moho, ~20 km at RTC and nearly 38 km at TAM,
although both have gradational velocity increases with depth.
