A seismological network was operated at the junction of the aseismic Walvis Ridge with the northwestern Namibian coast. We mapped crustal thickness and bulk Vp/Vs ratio by the H‐k analysis of receiver functions. In the Damara Belt, the crustal thickness is ~35 km with a Vp/Vs ratio of <1.75. The crust is ~30 km thick at the coast in the Kaoko Belt. Strong variations in crustal thickness and Vp/Vs ratios are found at the landfall of the Walvis Ridge. Here and at ~150 km northeast of the coast, the crustal thickness increases dramatically reaching 44 km and the Vp/Vs ratios are extremely high (~1.89). These anomalies are interpreted as magmatic underplating produced by the mantle plume during the breakup of Gondwana. The area affected by the plume is smaller than 300 km in diameter, possibly ruling out the existence of a large plume head under the continent during the breakup.

No abstract

Recently, a swarm of seismic events occurred within the Kunene region (NW of Namibia) with magnitude values going up to ML 4.6. Some of the events alarmed the Anker community and have become of national interest. In order to understand the source of this seismic activity, the Geological Survey of Namibia (GSN) and the Council for Geoscience (CGS) of South Africa installed a temporary network of 10 seismic stations in the Anker area to monitor seismicity for a period of 3 months from 20 June to 24 September 2018. More than 1600 microseismic events were recorded and located within the boundaries of the array, which was roughly 50 km × 50 km. The stations were installed in a 50 km × 50 km radius to have an accurate overlap of the network coverage and also by the spatial distribution of the known seismicity in the study area. The magnitude of the events ranged from ML − 1.1 to 3.6 and occurred at depths of less than 20 km. To improve the location of earthquakes, a new velocity model was developed using high-quality seismic dataset recorded by the temporary network. The seismic data was used to determine a minimum 1-D velocity model, which was used for the relocation of the earthquakes using the double difference method. The relocated solutions provided information to explain the seismotectonics of the region and establish the source of the current seismic swarm. Lineaments were mapped using magnetic data to identify the sources of the seismicity. Focal mechanism analysis of some of the events indicates the area is highly faulted with predominantly normal faulting.