Slip tendency applied to faults systems in the Congo Basin and its surroundings: A clue to explain western central African passive margin seismicity.
Discipline
Earth and related Environmental sciences
Subject
Geodynamics and mineral resources
Audience
Scientific
Date
2021Metadata
Show full item recordDescription
The Congo basin and its surrounding orogens in the western Central African region had been experiencing several earthquakes, even though quite few studies had attempted to explain their occurrences. The link between the recent seismicity and known faults does not look straightforward. The analysis of seismic history of the onshore and offshore areas revealed that the earthquakes are occurring on pre-existing fault systems of the Congo Basin, its surroundings units, and along near-shore extensions of the oceanic transform faults. In addition, the western Central African passive margin is undergoing two principal stress regime, one which is a ENE-NE trending horizontal compression in a thrust regime, and the other which is a normal faulting regime. Using the slip tendency method, the application of these present stress regimes on the mapped pre-existing fault systems which are mostly high-angle strike-slip faults systems, suggest that it is difficult to reactivate these faults under a thrust faulting stress regime, but more easily in a normal faulting stress regime. As most of the earthquakes occur at upper-crustal depths, we propose three hypotheses: 1.) there might be a brittle shear zone at depth that is accommodating tectonic reactivation leading to seismogenic rupture, which could be achieved by landward stress transmission by oceanic transform faults; 2.) these earthquakes might be generated by plate uplift and gravitational collapse; 3.) some of the events may have been triggered by local anthropogenic stress perturbation. The second hypothesis is quite probable as the western Central African margin has experienced repeated episodes of tectonic uplift in the Cenozoic as recorded in the Congo Basin. A thorough seismic analysis of the western Central African margin would provide more insight into the most probable causative mechanism for the earthquakes.
Citation
Nkodia, H.; Miyouna, T.; Boudzoumou, F.; Kolawole, F.; Delvaux, D. (2021). Slip tendency applied to faults systems in the Congo Basin and its surroundings: A clue to explain western central African passive margin seismicity.. , 7th International Geologica Belgica meeting Geosciences Made in Belgium , 15-17 September 2021, AfricaMuseum, Tervuren, Belgium, Vol. Abstract book, p. 322.,Identifiers
Type
Conference
Peer-Review
No
Language
eng