Comparison between different techniques for evaluation of predominant periods using strong ground motion records and microtremors in Pereira Colombia

This paper presents a comparison between different techniques for evaluatio n of predominant periods in soft soil, for the urban area of Pereira city,W estern Colombia. In this study we used microtremor and strong ground motion records obtained by a local array of seven accelerographs stations deploye d in the city. Response spectra and spectral ratios have been calculated an d compared with strong seismic events recorded in solid rock and soft soil stations. These observations allowed the determination of dominant response spectra for several sectors in the urban area. For the microtremor measure ments and earthquake data, dominant periods were determined using interpret ation of Fourier amplitude spectra and Nakamura's technique. A comparison b etween dominant periods obtained from strong ground motion records and thos e obtained from microtremor measurements show similarities, which is in the range 0.2-0.5 s. A preliminary version of a site response map for Pereira city was obtained from this analysis. (C) 2000 Elsevier Science Ltd. All ri ghts reserved.