Geophysical Measurements for Seismic Microzonation of the City of Huelva, Spain

One of the targets of the ALERTES-RIM (Regional and on-site earthquake early warning system for the Ibero-Maghrebian region) project is the characterization of the seismic soil response in the city of Huelva (Spain) in order to perform site effects quantification and microzonation mapping. The aim of this work is the application of a methodology based on combination of passive and active seismic techniques in order to define soft soil layers present in the study area. In this sense, H/V spectral ratio method is used throughout the city in order to know the soil fundamental frequency. Seismic noise array technique and surface wave analysis (MASW) are performed to obtain shear-wave velocity profiles of the soft soils at the different geological setups across the city. P-wave seismic reflections present in the active seismic dataset was used to map the overburden – bedrock interface as well as to image overburden reflectors. Finally, combining all these results together with the boreholes information has allowed delineating soft soil layers topography and the bedrock geometry all over the city. All this information will be used to compute ground motion amplification due to site effects and to perform microzonation studies in the city of Huelva.