Love wave contribution to the ambient vibration H/V amplitude peak observed with array measurements

Abstract

To cite this version:Brigitte Endrun. Love wave contribution to the ambient vibration H/V amplitude peak observed with array measurements. Journal of Seismology, Springer Verlag, 2010, 15 (3) Abstract: This study applies array methods to measure the relative proportions of Love and Rayleigh waves in the ambient vibration wavefield. Information on these properties is of special relevance for frequencies around the horizontal-to-vertical (H/V) spectral amplitude ratio peak. The analysis of H/V curves, a popular technique in site characterisation, commonly assumes that the curves represent the frequency-dependent Rayleigh wave ellipticity. For the detailed interpretation of amplitudes or the inversion of the curves, it is therefore necessary to estimate and correct for the contribution of other wave types to the ambient vibration wavefield. I use available ambient vibration array measurements to determine the relative amount of Love and Rayleigh waves on the horizontal components by frequency-dependent analysis of the main propagation and polarisation directions, with a special emphasis on the H/V peak frequency as determined from the same recordings. Tests with synthetic data demonstrate the feasibility of this approach, at least in the presence of dominant source regions. Analysis of the data from 12 measurements at nine European sites, which include shallow as well as deep locations that span a wide range of impedance contrasts at the sediment-bedrock interface, indicates that the relative contribution of Rayleigh waves varies widely with frequency, from close to 0\% to more than 70\%. While most data sets show relative Rayleigh wave contributions between 40\% and 50\% around the H/V peak, there are also examples where Love waves clearly dominate the wavefield at the H/V peak, even for a site with a low impedance contrast. Longer-term measurements at one site indicate temporal variations in the relative Rayleigh wave content between day-and nighttime. Results calculated with the method introduced herein generally compare well with results of modified spatial autocorrelation analysis. These two methods might be used in a complimentary fashion, as both rely on different properties of the ambient vibration wavefield. This study illustrates that it is possible to measure the relative Rayleigh wave content of the noise wavefield from array data. Furthermore, the examples presented herein indicate it is important to estimate this property, as the assumption that there are an equal proportion of Love and Rayleigh waves is not always correct.Response to Reviewers: Please refer to the uploaded PDF file ResponsetoReviewersJOSE405.pdf Abstract This study applies array methods to measure the relative proportions of Love and Rayleigh waves in the ambient vibration wavefield. Information on these properties is of special relevance for frequencies around the horizontalto-vertical (H/V) spectral amplitude ratio peak. The analysis of H/V curves, a popular technique in site characterisation, commonly assumes that the curves repre...

Joint inversion of spatial autocorrelation curves with HVSR for site characterization in Newcastle, Australia

“…Although the values of HVSR curves are unstable due to Love waves, body waves or other types of noises (Zor et al, 2010;Endrun, 2011), fitting of the shape of HVSR curves has still meaningful as Zor et al (2010) did by using zero-lag cross correlation.…”

Joint analysis of Rayleigh-wave dispersion curves and diffuse-field HVSR for site characterization: The case of El Ejido town (SE Spain)

“…Since effects of Love waves, higher modes of Rayleigh waves and body waves in the HVSR are not always negligible (e.g. [67,68]), full-wavefield inversions are definitely more suitable than oversimplified approached based on modelling the HVSR of noise by the Rayleigh wave ellipticity (e.g. [26,69]).…”

Slowly-attenuating P-SV leaky waves in a layered elastic halfspace. Effects on the coherences of diffuse wavefields

“…Endrun [22]). This topic has essential implications in seismic site effects evaluation and important consequences regarding the applicability of passive seismic methods of seismic exploration.…”