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Department of Geology, University of Jordan, Amman, Jordan

ABSTRACT

The Dead Sea is a morphotectonic depression that is characterised by strike-slip and normal faults, local and regional uplift and subsidence. Its tectonics are directly related to the opening of the Red Sea which resulted in a major shear that extends along the Dead Sea farther north to the Taurus-Zagros continental collision zone. This opening and the consequent shear are presently active and are responsible for the seismicity of this region.

The problem of induced seismicity associated with the creation of large water reservoirs is caused by the triggering of tectonic stresses affecting the rocks at critical rates close to their strength through (i) increasing the vertical stress caused by the water load (ii) increasing pore pressure due to either diffusion or direct flow of water through fractures (iii) thermal pressure caused by cool water entering hot rocks. Increasing the water level of the Dead Sea by 10m will increase both vertical stresses and pore pressures by some 1.2bars which is likely to trigger critically stressed faults. The seismicity of normal faults will therefore increase immediately after water increase, while that of strike-slip faults will start some time later when the pore pressure had risen. As damaging tectonic earthquakes are expected to occur in the Dead Sea area, this induced phenomenon may affect the time, location, depth and details of failure of these earthquakes.