Fracture network mapping using remote sensing in three crater lakes environments of the Cameroon volcanic line (central Africa)

Abstract

Lakes Monoun, Nyos, and Oku are three neighbouring crater lakes located in the active area of the Cameroon Volcanic Line (CVL) which structural and geodynamical state remains less known and does not allow to understand why only the first two are the seats of CO2 storage and exploded in 1984 and 1986 respectively. To carry out the structural and geodynamical study, the lineaments were extracted manually using pre-processed radar images with a resolution of 10 m. Structurally, the results show new many major faults and fractures densified around the lakes Nyos and Monoun, measuring respectively at least 12.7 km and 21.5 km, contrary to the lake Oku crossed only by minor fractures. Geodynamically, the results also reveal that the lakes Monoun and Nyos seats of limnic eruptions are located in the moderately active region of the CVL, while the lake Oku which has never been the site of limnic eruption is located in the most active area. So, the storage and gases emission of lakes Monoun and Nyos are not controlled by the geodynamical activity of their environments but, by the major and deep faults interconnected with major and minor fractures that crossing the two crater lakes, carrying the gases from the depths to the surface.