Seismic hazard assessment of the Hajiabad tunnel site, south of Iran, as determined from deterministic and probabilistic analysis approaches

In this research, seismic hazard assessment of the Hajiabad tunnel site in the Hormozgan province, southern Iran, have been determined using deterministic and probabilistic seismic hazard analyses models, and the obtained results have been detailly analyzed and discussed. For this purpose, active seismic sources and faults in a radius of 100 km of the tunnel site have been identified, and their characteristics such as orientation and their distances from the site were determined. Then, the maximum credible earthquake and peak ground acceleration due to the activity of the faults have been calculated using the above-mentioned approaches. Finally, the maximum horizontal and vertical ground accelerations in a 50-year time period for different levels of seismic design have been calculated using the reduction relations for the input, middle, and output sections of the tunnel. In the studied site, there is possibility to occur earthquakes with magnitude higher than 4 in Richter scale, which can cause a maximum ground acceleration of 0.3 g. The annual occurrence probability of the earthquakes greater than 4, 5, 6, and 7 Richter in a 111-year time period are 1.495, 0.360, 0.081, and 0, respectively. Thus, their return periods are 0.669, 2.775, 12.333%, and ∞ years, respectively.