West Coast Fault – Real or Factitious Earthquake Threat to United Arab Emirates

The Municipality of Abu Dhabi City in 2008 initiated complex multidisciplinary project “Seismic Hazard and Risk Assessment of the Emirate of Abu Dhabi, AD-SHRA” consisting of 20 tasks and 69 deliverables. Implementation of AD-SHRA project commenced by the end of 2010. The Task “Seismic Hazard Assessment and Seismic Zoning of UAE” is completed. Its objectives have been to: (1) compile all available data on the seismicity of the Arabian Gulf, including review of all past seismic studies and other assessments; (2) obtain a conservative, but reliable, estimate of the seismic hazard for UAE; and, (3) produce 2% 50 years (return period 2475 years) Ss and S1 seismic zoning maps as a base for official UAE seismic zoning to accompany IBC 2009 Design Code presently under adoption in UAE. Until recently Arabic craton has been treated as stable, almost aseismic. A number of studies of the seismic hazard in the UAE have been published since 1999, presenting diverse interpretations of the earthquake threat in this country of relatively low local seismicity. The major generator of high levels of ground motion associated with a 475-year return period is found either in seismic source modeling that spread seismicity from allochthonous (Zagros, Iran or Makran subduction zone, southern Pakistan -- south-eastern Iran) into the Arabian Peninsula, use of the ground-motion prediction equation derived from Iranian strong-motion data, or inclusion of so called Western Coastal Fault (WCF, referred also as Coastal Plane Fault, CPF) in seismic hazard assessment as an autochthonous tectonic structural element. Results of such seismic source modeling are quite contradictory. For example, Al-Hadad et al (1994, [2]) suggests that UAE is almost aseismic, Grunthal et al (1999, [3]) that it is an area of high seismic risk, whereas Shama (2011, [17], Fig. 1,) based his seismic hazard assessment on an almost apocalyptic seismotectonic setting which paramount contributor is WCF. Intention of this contribution is not focused on scientific, research and methodological particularities of seismic hazard assessment of UAE, but to present findings and to affirm the position of Municipal Project Team related to the existence of WCF structural tectonic element.