Attenuation characteristics of Turkey based on recent strong motion data

Abstract

This paper deals with the derivation of a consistent set of empirical attenuation relationships for predicting free-field horizontal components of peak ground acceleration (PGA) and 5 percent damped pseudo acceleration response spectra (PSA) from 47 strong ground motion records recorded in Turkey. The relationships for Turkey were derived in similar form to those previously developed by Boore et al. [1] for shallow earthquakes in western North America. The used database was compiled for earthquakes with moment magnitudes $(M_w)geq 5$ that occurred between 1976-1999, and consisted of horizontal peak ground acceleration and 5 percent damped response spectra of accelerograms recorded on three different site conditions classified as rock, soil and soft soil. The empirical equations for predicting strong ground motion were typically fit to the strong motion data set by applying nonlinear regression analysis according to both random horizontal components and maximum horizontal components. Comparisons of the results shows that ground motion relations for earthquakes in one region cannot be simply modified for use in engineering analyses in another region. Our results, patterned after the Boore et al. expressions and dominated by the Kocaeli and Düzce events in 1999, appear to underestimate predictions based on their curves for up to about 15 km. For larger distances the reverse holds.