Local site response in San Salvador, El Salvador: Comparison between microtremors, weak-motion and strong-motion.
Autor:
Kuvvet, Atakan; Ciudad Real, Mauricio; Torres, Rodolfo; Figueroa, Juan Carlos; Arias, Roberto; Santos, Pedro.
Fuente:
Noruega; s.n; abr. 1994. 34 p. mapas, tab, graf. (Reduction of Natural Disaster in Central America: Earthquake Preparedness and Hazard Mitigation, 12).
Data from four sites within the metropolitan area used to investigate the local site response in San Salvador. Spectral ratios of the horizontal components from the four records of one minute duration background noise (microtremors), earthquakes from the subduction zone (weak motion) and the earthquake of Oct. 10, 1986 (strong motion). Results indicate site amplifications ranging from 3-9 at all sites on all three data sets within the frequency band 1.0-10.00 Hz. However, within this frequency band, no correlation is found at any dominant frequency. This is probably due to the variations in the thicknesses and the properties of the sedimentary layers both vertically and laterally. Average amplification factors obtained from the three data sets show a trend indicating a gradual decrease from microtremors to weak and to strong motion. Estimates on all four sites indicate higher values (5.1-8.5) for microtremors compared to the weak motion data (4.5-6.8), whereas strong motion data shows the lowest amplification factors (3.3-4.5). In order to obtain reliable estimates of site amplification, this nonlinearity between the three data sets have to be taken into account. Unless calibrated with the strong motion data, caution is recommended in using microtremors (Au) - en
