An improvement on the use of empirical green functions for ground motion synthesis to predict Tehran's main earthquake

Abstract

This research presents potential use of the empirical green function (EGF) approach and kinematic rupture models as a predicting tool in strong ground motion seismology. The former applications of EGF were employed on very small earthquakes, so the results were not reliable for almost all earthquakes recorded in the crowded metropolitan areas, due to improper signal to noise ratio. The method used in this study for prediction of strong ground motion provides an accurate and defendable means to characterize site and path affects, and thus limits uncertainties from predicted hazards to unresolved issues about the earthquake source such as the geological constraints of a particular fault. This approach, with the identified probable causative fault, was demonstrated for the 2004 Firoozabad-Kojoor earthquake, a major earthquake located close to Tehran. Then the potential of this approach as a prediction tool in strong ground motion seismology was examined. The results showed that the actual ground motion recordings fell within the range of synthesized ground motions. Furthermore, reasonable strong ground motion “predictions” were achievable even without having an extensive knowledge of the fault characteristics. Finally, the proposed method was applied to predict the pseudo acceleration spectra and design spectra for the city of Tehran. Key words: Earthquake, empirical green functions, ground motion synthesis, spectra, Tehran earthquake.