Investigating the Geological Fault Framework Offshore Lebanon: Insight into the Earthquake Geology of the Region

Abstract

The tectonic setting of Lebanon in the eastern Mediterranean region is a restraining bend along the Dead Sea Transform Fault, which is the plate boundary between Arabia and Africa. Within the Lebanese Restraining Bend, the plate boundary splays into several fault branches that are mapped onshore Lebanon and known to have contributed to the evolution of the Lebanese structural framework. However, little is known about the geological structures offshore Lebanon, and how those structures could relate to the onshore tectonics. Such information is very useful in understanding the tectonic framework of the region from two perspectives: (1) earthquake geology and (2) petroleum geology. The objective of this thesis is to investigate and study, through 3D seismic interpretation, the tectonic framework offshore Lebanon. This provides a wealth of needed insight into the earthquake geology of the region. In addition, mapping the faults offshore Lebanon and understanding their tectonic behavior can provide valuable comprehension of the elements of the hydrocarbon systems in the Lebanese part of the Levant basin. A bathymetric map of the Lebanese offshore area is generated and used to delineate the faults’ surface features. The major and minor faults are interpreted and used to identify and understand the behavior of potential tsunami-generating structures. A previously interpreted thrust fault system offshore Lebanon referred to as ‘Mount Lebanon thrust’ was suggested to be responsible for the A.D. 551 earthquake, which was one of the most destructive in the history of the Levant. After careful investigation of the offshore area using 3D seismic data, we believe that this system is more a hypothesis than a reality. In addition, we propose that the Latakia ridge is a prominent structure that can trigger such tsunamigenic earthquakes. This thesis provides some insight into the earthquake and tsunami generation potential in the eastern Mediterranean area, together with additional input into future investigations of the hydrocarbon potential offshore Lebanon.