Are microtremors useful in site response evaluation?

Abstract

The paper reviews the applicability of microtremor measurments to evaluate site response of soft soils. Three different techniques commonly used to estimate site effects from microtremor measurements were evaluated: interpretation of Fourier amplitude spectra, computation of spectral ratios relative to a firm reference station, and computation of spectral ratios of horizontal components relative to the vertical component of ground motion (Nakamura's technique). These techniques are applied to microtremor records obtained in three cities in Mexico: Mexico City, Oaxaca, and Acapulco. The results strongly suggest that the techique by Nakamura effectively compensates for source effects in microtremor measurements, which eliminates a major limitation to their application in earthquake engineering. -from Authors