ACTIVE TECTONIC DEFORMATION ACROSS THE NORTHERN SHELF OF THE GULF OF AQABA/EILAT, DEAD SEA RIFT SYSTEM

New geophysical data of the northern part of the Gulf of Aqaba/Eilat (GAE), Dead Sea Rift were collected during two marine surveys in Oct/Nov. 2006 and February 2010 as part of the “High Resolution Marine Geophysical Imaging of Active Faults in the Aqaba-Eilat Region” project funded by MERC. Multibeam sonar data were used to generate the first detailed bathymetric map with a 2 m resolution across the entire northern Gulf of Aqaba/Eilat in Israel and Jordan. In total more than 1400 km of geophysical data lines including Sparker seismic reflection, magnetics, side-scan sonar, ground penetration radar, and electrical methods were acquired in the GAE and within the greater Aqaba municipality.

From interpretation of these geophysical data, we mapped the location of six previously unknown faults with varying degrees of seismic activity in the offshore and traced their potential continuation on land beneath the densely populated cities of Eilat and Aqaba. The Eilat and Aqaba faults along the margin of the gulf are zones of predominantly normal faults that accommodate subsidence of the basin. The most active strike-slip fault is the Evrona fault that projects from the shelf landward into the lagoon and hotel district of the city of Eilat. If the age model for the subsurface layers based on application of global sea level curves and climate variations is correct, then most of the recent plate motion is concentrated on this fault. This fault is also the most likely to have the largest amount of surface rupture in a future earthquake. Four faults appear to project from the offshore into the city of Aqaba.

The GAE shelf is oriented at a high angle to the main trend of the Dead Sea transform boundary. The shelf sedimentary sequence is cross-cut by several, subparallel faults that flank the east and west margins of the basin and faults that trend obliquely across the basin. These faults divide the gulf head into the Eilat and Aqaba subbasins separated by the Ayla high. West of the high, the Eilat subbasin receives a large amount of sediment that is transported to the deep basin by slumping and gravity sliding along the Eilat submarine canyon. Seafloor lineaments defined by slope angle analyses suggest that the Eilat canyon and the eastern boundary of the Ayla high align along northwest-striking fault systems. The shelf-slope break that lies along the 100 m isobath in the Eilat subbasin and shallower in the Aqaba subbasin is offset by approximately 150 m along the east edge of the Ayla high. Our preliminary interpretations of these data suggest block deformations with localized depocenters that migrate as the blocks adjust to changes in the localized strain. Submarine failures, identified from the high-resolution image of the seafloor, appear to be highly concentrated on the west side of the GAE and may be associated with the higher seismic activity on the Evrona fault. Submarine failures are likely triggered by earthquakes and could potentially produce local tsunami hazards. These data are particularly important for the safety and monitoring of marine infrastructure (e.g. the port and pipelines) and in future planning of infrastructure (e.g. Red Sea-Dead Sea canal, desalination plants, etc.) in the region.