From ambient noise recordings to site effect assessment: The case study of Barcelona microzonation

As local site effects have a drastic influence on seismic hazard, it is a major issue to characterize them in vulnerable areas such as highly urbanized zones, like Barcelona city. The aim of this work is to improve the knowledge of geophysical characteristics of Barcelona in the perspective of a seismic microzonation that takes into account site effect. The first step was to gather the existing data from geological, geotechnical, geophysical, and seismological investigations, bringing us to keep the four zones proposed by previous work as a base of zonation. The second step was to characterize each zone by time-averaged shear-wave velocity and fundamental resonance frequency, with ambient noise techniques over 17 sites, providing new knowledge about the soil of Barcelona. The third step was to propose an amplification function between an average soil for each zone and a standard reference rock site, using empirically based propositions and to compare them to previous numerical approaches.