Walvis Ridge Passive-Source Seismic Experiment - Seismic structures and seismotectonics in the passive continental margin of NW Namibia

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The Etendeka continental flood-basalt province in northern Namibia, linked by the Walvis Ridge to the Tristan da Cunha hotspot, has a great importance in global plate tectonic concepts, and is an ideal place to understand the roll of the plume-lithosphere interaction during break-up of the Southern Atlantic Ocean. We propose to operate an amphibian passive-source seismic network at the position, where the Walvis Ridge intersects with the continental margin of northern Namibia. The broadband seismic network will be composed of 20 three-component land stations and 12 ocean-bottom stations, and will be operated for 1-1.5 year. Together with a permanent station in Tsumeb and data from a previous seismic experiment, we are going to have 38 on-/off-shore stations covering an area of approximately 400 km x 800 km. This configuration of stations will allow us to map the lithospheric and deeper upper mantle structure in the ocean-continent transition beneath the passive continental margin of northern Namibia and to find seismic anomalies related to the postulated hotspot track from the continent to the ocean along the Walvis Ridge. The acquired data can also be used to study the velocity anomaly in the lowermost mantle caused by the Africa super plume. This proposal is part of the first attempt to map a classical plume/flood basalt province with the existing geophysical methods to unravel the impact of the break-up in the lower crust and mantle lithosphere. The new seismic data will provide the basis for multi-disciplinary synthesis and integration of results within this SPP program.