Modelling site amplification effects for eastern Cuba

Abstract

The expected soil amplification has been computed for eastern Cuba considering two combined methods: a geological approach, based on the soil classification (actually two alternative methods: from surficial geology and deep lithology), and a geotechnical method, based on 1D modelling. Based on the regional geological maps, soil category maps and regional geological profiles, 45 geological models (26 for rock and 19 for surficial deposits) have been established for the entire study region. Adding the information from deep borehole data, 36 geotechnical models have been identified to represent the 19 surficial deposits in the study region, plus one for rock. In fact, after a preliminary soil characterization based only on surficial geology, the mechanical properties and thickness of the different layers within the first 30 m have been considered as main geological characteristics to identify the soil class and the related V S30 , according to the NEHRP provisions, and the related proper amplification factors (AFs) have been derived. In addition, 1D soil modelling has been performed to obtain soil AFs in the homogeneous sectors in which the study region has been partitioned. A comparison performed between the AFs calculated by modelling and those estimated in agreement with the NEHRP provisions has shown quite large differences. These results, although not representing a substitution for a real microzonation study, can be useful in improving seismic hazard estimates for a general seismic risk quantification, urban planning, and seismic code updating.