Nicy Carmel Bazebizonza Tchiguina^{1, 2,}, Timothée Miyouna¹, Hardy Medry Dieu-Veill Nkodia¹, Florent Boudzoumou^{1, 3}

Several studies have stated the possibility of seismic hazards in the Congo Basin area. This study aims to conduct a morphometric analysis of the Inkisi Group which constitutes a part of the subsoil of the south-eastern Republic of Congo (RC) and the south-western part of the Democratic Republic of Congo (DRC), to detect neotectonic signatures. GIS and ASTER GDEM images have enabled the automatic extraction of morphometric indices, in particular the Hypsometric Integral (HI), the Relative Declivity Extension (RDE) index, along with the hydrographic network and its frequency density. Analysis of the hypsometric distribution of watersheds in the Congo Basin highlights two relief trends. The first relief trend is high (HI>0.5) and is represented by young and abrupt-type basins suggesting rejuvenated relief by neotectonics. The impact of neotectonics in this rejuvenation is evidenced by the RDE index, which reveals that the first order knickpoints in the drainage gradient are mainly located in these watersheds at HI>0.5. The second relief trend is low (HI<0.5) and encompasses the basins tending towards the "equilibrium" stage in which neotectonics is less active. The young basins constitute a NE-SW oriented strip that borders on both sides of the Congo River, thus revealing elevated seismic risk on these two banks. In the Republic of Congo, these young basins perfectly overlap the high lineament density network of the Inkisi group. Moreover, the densest areas of knickpoints in the drainage gradient are located along the course of the Congo River. Thus, the course of the Congo River corresponds with a tectonically active feature; the installation of seismographs along its borders is strongly recommended to better assess the seismic risk associated within it.

Neotectonics, Morphotectonics, Knickpoint, Inkisi, Congo