Abstract

On 12 November 1999, only three months after the 17 August 1999 Kocaeli earthquake (Mw 7.4), an earthquake of Mw 7.1 occurred immediately to the east of the Kocaeli rupture in northwestern Turkey resulting in extensive structural damage in the city of Düzce and its surrounding area. It was reported to be a right-lateral strike slip event on the previously unbroken segment of the North Anatolian fault zone with a north-dipping fault plane. This paper presents stochastic finite-fault simulation of near-field ground motions from this earthquake at selected near-fault stations based on a dynamic corner frequency approach using the computer program EXSIM (Motazedian and Atkinson, 2005). The method requires region-specific source, path, and site characterizations as input model parameters. The source mechanism of the 1999 Düzce event and regional path effects are well constrained from previous studies of the earthquake. The local site effects at the selected stations are studied as a combination of the kappa operator and frequency-dependent soil amplification. The model parameters are validated against recordings and a stress-drop value of 100 bars is estimated for the 1999 Düzce earthquake. The validated model is then used to compute synthetic records around the fault. Distribution of peak ground-motion parameters is observed to be consistent with the building damage distribution in the near-fault region most affected by the seismic shaking. The attenuation of synthetic ground-motion parameters is compared with recent ground-motion prediction equations proposed for the region by Gülkan and Kalkan (2002), Ulusay et al. (2004), and Akkar and Bommer (2007), as well as two next generation attenuation models by Boore and Atkinson (2007) and Campbell and Bozorgnia (2007). Despite discrepancies at several stations, stochastic finite-fault modeling based on a dynamic corner frequency approach confirms to be a practical tool to reproduce the ground motions of large earthquakes.

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