ESTIMATING THE STRONG-MOTION OF THE DECEMBER 26, 2003 BAM (IRAN), EARTHQUAKE USING STOCHASTIC TECHNIQUES

The main objective of this study is estimating the strong motion for the Bam region using the stochastically based seismological models. The two widelyused synthetic techniques namely; point-source and finite-fault were utilized incorporating the source-path and site parameters into simple function. The decay factor kappa was estimated based on the data obtained from recorded strong motions to be used as an appropriate factor for the region. The results were validated against those of the recorded data during the destructive 26 December 2003 Bam earthquake in south east of Iran. The efficiency of these methods and estimating the appropriate regional model parameters are the main objectives of this study. The results of the synthesized ground motion, such as acceleration time history, PGA and elastic response spectra were compared /assessed with those of observed data. The Bias model (MB) is used to assess the validation of the simulated earthquakes against recorded horizontal acceleration time histories. The %90 confidence interval of the means averaged over the whole stations using t-student distribution was evaluated and it was shown to be in an acceptable range. The elastic response spectra of the simulated strong motion are showed to be in a good agreement between the recorded waveforms confirming the acceptability of the selected/evaluated source-path-site model parameters. The sensitivity of the simulated PGA and response spectra against kappa factor as well as the pathaveraged frequency-dependent quality factor Q, is studied and discussed.

Keywords:

Stochastic model , Ground motion simulation , Point source , Finite-Fault model , Bam