ABSTRACT
The main purpose of the paper is the analysis of seismic site effects in Caracas (Venezuela). The analysis is performed considering the Boundary Element Method and is compared with experimental results (damage of real earthquakes, in situ microtremors measurements). A numerical model including a part of the local topography is considered, it involves an homogeneous alluvial deposit on an elastic bedrock. The amplification of seismic motion (SH-waves) is analyzed in terms of level, occuring frequency and location. In this specific site of Caracas, the amplification factor is found to reach a maximum value of 25. Site effects occur in the thickest part of the bassin for low frequencies (below 1.0 Hz) and in two intermediate thinner areas for frequencies above 1.0 Hz. The influence of incidence is also investigated. A comparison with H/V ratio obtained from microtremor records is presented afterwards. The analysis of the damages observed in Caracas after the strong 1967 earthquake are also compared with the numerical results (amplification level and location). The results of both numerical and experimental approaches are in good agreement in terms of frequency and location of maximum amplification. The boundary element method appears to be a reliable and efficient approach for the analysis of seismic site effects.
