Evidence of Quaternary active folding near Utique (NE Tunisia) from tectonic observations and a seismic profile

Lassaad Mejri (1, 2, 3) , Vincent Regard (1) , Sébastien Carretier (1) , Stéphane Brusset (1) , Mahmoud Dlala (3)

1 LMTG - Laboratoire des Mécanismes et Transfert en Géologie
2 CNSTN - Centre National des Sciences et Techniques Nucléaires
3 FST - Faculté des Sciences Mathématiques, Physiques et Naturelles de Tunis

The present-day seismicity at northeastern Tunisia reported from permanent networks is of low to moderate magnitude. However, earthquakes are mentioned in the literature, specially a destructive one in the antique city of Utique. Geologic, seismic, and neotectonic investigations in this area shows that Utique fold is closely related to the recent tectonic activity in this region. Data show that Utique fold is built on an E-W fault, and we found evidence of activity of this fault in the past 20 kyr. Seismic section and balanced cross section shows that slip rate is of 0.38 mm.yr-1. Our data show definitively the late Pleistocene–Holocene activity of the Utique Fault; and we can predict the earthquake recurrence interval which should be of ~103-104yr. This high seismic risk zone deserves to be taken into account during the establishment of important regional development programs and in the application of seismic building code.

Mots clés: Atlas; Tunisia; Active tectonics; Fault-propagation folding; Utique; Quaternary; Pliocene

Domaines: Géomorphologie; Tectonique; Milieux et Changements globaux

Lassaad Mejri, Vincent Regard, Sébastien Carretier, Stéphane Brusset, Mahmoud Dlala. Evidence of Quaternary active folding near Utique (NE Tunisia) from tectonic observations and a seismic profile. 2010. ⟨hal-00504302⟩