EMPIRICAL EVALUATION OF THE HORIZONTAL-TO-VERTICAL SPECTRAL RATIO TECHNIQUE: RESULTS FROM THE “SESAME” PROJECT

In order to empirically evaluate the horizontal-to-vertical (H/V) spectral ratio technique, ambient noise measurements performed in about two hundred sites mainly in Europe where weak or/and strong motion data was recorded. Standard Information Sheets (SIS) and earthquake information data were included in the SESAME [Site EffectS assessment using AMbient Excitations] project database, specially designed to facilitate data selection. All noise recordings were processed with JSESAME software to calculate (H/V) spectral ratio, whereas weak and strong motion earthquake recordings were processed with a similarly standardized procedure. For the latter, (H/V) receiver function for all sites were calculated. Experimental site transfer functions obtained from earthquake recordings were compared with the (H/V) spectral ratios from noise recordings in terms of fundamental frequency, amplification bandwidth and amplification level. Similarities and differences between (H/V) spectral ratio of noise and earthquake recordings are presented and discussed. In addition, a dense grid of noise measurements were performed within urban environment of cities affected by strong earthquake (Greece: Thessaloniki, Kalamata, Italy: Palermo). It seems that the (H/V) spectral ratio may satisfactorily indicate areas favorable to the occurrence of higher damage in urban environment. However, quantitative correlation between (H/V) spectral ratio properties and damage distribution (macroseismic intensity, damage grades) in some cases, is difficult to be established given the complexity of parameters involved

Observation of the spread of slow deformation in Greece following the breakup of the slab

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