Microzonificación sísmica en entornos urbanos mediante análisis de parámetros geotécnicos: área metropolitana de Girona (NE Cataluña, España)

A synthesis of the methodological procedures and results of a seismic microzonation study carried out in the metropolitan area of Girona (NE Catalonia, Spain) is presented here. A statistical analysis of a geotechnical database has been conducted in order to correlate geotechnical variables of seismic significance with soil dynamic parameters, by means of the Spanish Seismic Building Code (NCSE-02) specifications. For all the litho-stratigraphical units present in the area, the obtained parameters are soil coefficient C, and shear wave velocities Vs. A casuistic matrix of typological cases has been defined for the attribution of individual C to each lithological level identified in a borehole, by taking into account weighted percentual contribution of both on site geotechnical data and statistically representative values. This has led to C calculation for 87% out of 1,530 boreholes. The resulting microzonation considers C intervals in the delineation of four zones of seismic isoamplification related to soil effects. This study sets a basic source for more advanced seismic studies like geophysical measurement surveys, numerical modelling and simulation of risk scenarios.