Probabilistic Seismic Hazard Assessment of Tehran Based on Arias Intensity

A probabilistic seismic hazard assessment in terms of Arias intensity is presented for the city of Tehran. Tehran is the capital and the most populated city of Iran. From economical, political and social points of view, Tehran is the most significant city of Iran. Many destructive earthquakes happened in Iran in the last centuries. Historical references indicate that the old city of Rey and the present Tehran have been destroyed by catastrophic earthquakes at least 6 times. Existence of active faults like North of Tehran, Mosha and North and South of Rey is the main causes of seismicity of this city. Seismicity parameters on the basis of historical and instrumental earthquakes for a time period, from 4th century BC to the present time are calculated using Tavakoli’s approach and Kijko method. The earthquake catalogue with a radius of 200 km around Tehran has been used to calculate seismicity parameters. Iso-intensity contour lines maps of Tehran on the basis of different attenuation relationships are plotted. They display the probabilistic estimate of Arias intensity with Rock and Soil beds for the return periods of 72, 224, 475, 2475 years. SEISRISKIII software has been employed for seismic hazard assessment. Effects of different parameters such as seismicity parameters, length of fault rupture relationships, and attenuation relationships are considered using logic tree.