Active faults' geometry in the Gulf of Aqaba, southern Dead Sea fault, illuminated by multi beam bathymetric data

Abstract

Detailed knowledge of fault geometry is important for accurate seismic hazard assessment. The Gulf of Aqaba, which corresponds to the southern termination of the 1200-km-long Dead Sea fault system, remains one of the least known parts of this plate boundary fault, in large part due to its location offshore. Classically, the Gulf of Aqaba has been described as a succession of three pull-apart basins. Here, building on a new multibeam bathymetric survey of the Gulf of Aqaba, we provide details about the geometry of the faults at the bottom of the gulf that controls its morphology. In particular, we identify a 50 km-long fault section that shows evidence of recent activation. We associate this fault section (Aragonese fault) with the main fault section that ruptured during the 1995 magnitude Mw7.3 Nuweiba earthquake. In the southern part of the gulf, bathymetry emphasizes the strike-slip nature of the Arnona fault, while dip-slip motion seems to be accommodated mostly by faults located along the eastern edge of the gulf. Considering the simple linear geometry of the Arnona fault and the absence of any large earthquake for several centuries, despite an average slip-rate of ∼5 mm/yr, this fault should be considered as a significant candidate for an earthquake rupture of magnitude 7 or above in the near future.