Strong motion records from the Oct. 10, 1986 earthquake are used to investigate the local site response in San Salvador. Spectral ratios of the horizontal components from four sedimentary sites with respect to a reference site, indicate maximum amplifications by a factor of 8-22. The amplifications vary at different sites, largely depending on the frequencies. There is generally a good correlation between the type of the sediment and the amplifications. Our results give some evidence for positive correlations between the two data sets. However, the synthetic records fail to estimate the site amplifications at lower frequencies and the estimates in the frequency range 1-5 Hz can only be used as a very rough approximation. Using synthetic records in estimating the local site response, may only be applicable when they are calibrated with observed data. Otherwise, the estimates from the synthetics are largely dependent on the input control motion. The results from the spectral ratios of the observed records, are therefore more applicable to the San Salvador area (Au) - en
