The Bisri dam project: A dam on the seismogenic Roum fault, Lebanon

Abstract

The Roum fault is a fault branch of the Dead Sea Transform Fault within the Lebanese Restraining Bend. It is an active seismogenic fault that was associated with the 1 January 1837 (Ms 7.1) earthquake, and whose extent has been the subject of great controversy within the restraining bend. In this paper, the Roum fault is revisited after a dam project (the Bisri dam) has been planned in one of the fault's most critical locations, i.e. in the Bisri valley that hosted the epicenter of the 16 March 1956 (ML 5.8) earthquake. The fault and its associated structures in the proposed dam area are discussed, and highlights on the dam site are made as a geologically complex and tectonically active area. The future water body behind the planned Bisri dam will overlie an active fault, with huge potential for fault movement underneath the dam footprint, liquefaction around the dam foundations, mass movements near the dam site, and direct effect on inducing seismicity on a delicate fault system that can potentially trigger a major earthquake that can affect the whole Lebanon and its surroundings. This requires special attention and in-depth considerations especially of the potential of reservoir-induced/triggered seismicity on the seismogenic Roum fault, and makes of the Bisri area a very unfavorable site for the proposed Bisri dam in Lebanon.