The aim of this research is to detect the neotectonic activity and to map the seismic risk potential in the plain of Kasserine using the longitudinal profile of the Htab River and its tributaries. The adapted methodological approach is based on the extraction of the longitudinal profile and knickpoints, which are the main source of seismicity information in a plain filled up with more than 1000 m of silty deposit. In such a plain, compact structures are absent and thus we cannot detect the

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... ary tectonic indices. The selected longitudinal profiles of the tributaries of the Htab River, extracted along the plain, show normal forms like river 1, 12 and 14 and abnormal ones such as 3, 5 and 7. The knickpoints distribution shows two main alignments trending NW-SE. The first one is in Semmama Mountain and it is represented in the structural map of Kasserine whereas, the second one is located in the plain of Kasserine and we think that it is caused by neotectonic activity. To confirm this hypothesis we use seismic records of the National Meteorology Institute since 2000. These data show seismic activity in the plain which is also a witness of a NW-SE alignment. Moreover, in situ investigations are performed and results pinpoint normal fault activity in the plain. Knickpoints, seismic records, and in situ investigation emphasize significant neotectonic activity affecting the thick quaternary plain of Kasserine.