From Non-invasive Site Characterization to Site Amplification: Recent Advances in the Use of Ambient Vibration Measurements

Abstract

A series of investigations has been carried out over the last decade in Europe aimed at deriving quantitative information on site amplification from non-invasive techniques, based principally on surface wave interpretations of ambient noise measurements. The present paper focuses on their key outcomes regarding three main topics. First, methodological, hardware and software developments focusing on the acquisition and the processing of both single point and array microtremor measurements, led to an efficient tool with in situ control and processing, giving rise to robust and reproducible results. A special attention has been devoted to the derivation and use of the Rayleigh wave ellipticity. Second, the reliability of these new tools has been assessed through a thorough comparison with borehole measurements for a representative – though limited – set of sites located in Southern Europe, spanning from stiff to soft, and shallow to thick. Finally, correlations between the site parameters available from such non-invasive techniques, and the actual site amplification factors as measured with standard techniques, are derived from a comprehensive analysis of the Japanese KIKNET data. This allows to propose alternative, simple site characterization providing an improved variance reduction compared with the “classical” VS30 classification. While these results could pave the road for the next generation of building codes, they can also be used now for regulatory site classification and microzonation studies, in view of improved mapping and estimation of site amplification factors, and for the characterization of existing strong motion sites

Guidelines for the good practice of surface wave analysis: a product of the InterPACIFIC project

“…The Reader is referred to textbooks (e.g. Okada 2003;Foti et al 2014) and to the vast literature on the topic (for an overview, see Bard et al 2010;Socco et al 2010;Foti et al 2011;Schramm et al 2012;Yong et al 2013) for achieving the necessary knowledge on surface wave methods and for the theoretical details.…”

Site effect assessment using KiK-net data: part 2—site amplification prediction equation based on f0 and Vsz

“…The simplicity and cost effectiveness come from the fact that each of the considered site parameters are easily available with non-invasive techniques: the shallow average velocities V SZ can be robustly estimated with active shallow seismic (MASW type: V S05 , V S10 , V S20 ), and passive array microtremor measurements (from V S05 to V S30 , see Renalier 2010 and Bard et al 2010), while the fundamental frequency is most generally provided by singlepoint microtremor measurements and H/V noise processing. Moreover the simplicity comes also from the fact that these functions keep a simple formulation with only two parameters (X ref1 and β gathered in the Appendix) for each frequency.…”

Surface wave surveys for seismic site characterization of accelerometric stations in ITACA

“…Both fundamental and higher Rayleigh wave modes were used for the inversion. A further constraint for the inversion was introduced the right branch of the mean HVSR curve (Bard et al 2010) for the ellipticity function. The results of the joint inversion of dispersion curves (interpreted as fundamental and second higher mode of Rayleigh waves) and ellipticity curve are shown in Figs.…”