Earthquake-induced flooding and paleoseismicity of the El Asnam, Algeria, fault-related fold

摘要: Late Quaternary activity of the El Asnam thrust fault (responsible for October 10, 1980, MS = 7.3 earthquake and 36-km coseismic faulting) is explored through diverse paleoseismological field methods. We trenched main secondary 1980 scarps, made an analysis earthquake-induced flood deposits, conducted a geomorphic study leveling profiles offset geological units across normal considered geomorphology active fold. Twenty-five radiocarbon ages from colluvial alluvial along with conventional (fossils artefacts) dating units, show timing successive net vertical displacements on thrust-related fold bending-moment faults. Previous work showed that eight pre-1980 earthquakes occurred in clusters during late Holocene. Cumulative slip amounts to 3 times displacement observed multiple scarps offsets Maximum cumulative displacements, which are visible different zones segments, can reach 10 25 displacements. The uplift rate 0.6 mm/yr, taking into account variation fault, this may range between 0.25 – 1.6 we obtain shortening 0.17 1.2 mm/yr. Because Tell Atlas mountains exhibit comparable seismogenic fault-related folds parallel sequential structures faults, total average 2.05 mm/yr represents part convergence accommodated Africa-Eurasia plate boundary.