High resolution seismic Tomography of Eastern Africa from global and regional datasets

Abstract:

The topography of the African continent and eastern surrounding basins are characterized by large-scale extensional features such as the East African Rift, Mozambique margins, widespread volcanic activity, and anomalously subsided basins and uplifted domes. These features have long suggested that the African continent is shaped by significant dynamic forcing originating in the underlying mantle.

We need detailed seismic tomography models to image patterns that might be associated to the East African Rift system and the major basins that characterize the topography of central and southern Africa and its surrounding areas.

Our method is based on a multi-resolution adaptive parameterization whose density changes locally depending on density of data coverage. This allows to embed our regional model in a global one, i.e. to maximize the resolution of our images by inverting regional and teleseismic observations jointly, without neglecting heterogeneity, outside the region of interest, that teleseismic data are sensitive to.

This method has been applied to global data before, resulting in the multi-resolution models SAVANI and SPANI. Our new model takes advantage on a great amount of data from various networks deployed in eastern Africa, Madagascar and offshore areas since the last 20 years. This results in a new global multi-resolution model with unprecedently high resolution on Eastern Africa.