Lineament characteristics using gravity data in the Garoua Zone, North Cameroon: Natural risks implications

Abstract

The Garoua Zone in North Cameroon, the subject of this study, is known to have undergone tectonic movements during the Cretaceous, but the zone’s structural data remain poorly known. This study exploits the Bouguer anomaly to improve knowledge of Garoua tectonics structures. In order to characterize these structures, two methods are used: Euler’s deconvolution method and the method of the horizontal gradient of the vertical derivative. Superposition of the Euler’s solutions map for index N=1 with the map from the horizontal gradient of the vertical derivative method allows determination of gravimetric lineaments, interpreted as faults or as linear contacts, from which we deduce a structural map of the study area. Based on this map, we identify sixteen lineaments, of which we count eight as linear contacts and eight as faults. Among the faults, we denote one of depth between 4 and 8 km, five faults of depth ranging between 8 and 13 km, and two faults of depths between 13 and 36 km. Analysis of these faults shows that the seven deepest faults might present a natural risk in our study area. For purposes of civil protection, such deep faults should be monitored and taken into consideration in the implementation of large public works. The structural map, established herein from data on the in-depth extension of each fault, thus increases scientific knowledge in the area that can be used to site public works in ways that reduce risk.