Joint inversion of H/V ratios and dispersion curves from seismic noise: Estimating the S‐wave velocity of bedrock

Picozzi, Matteo; Parolai, Stefano; Richwalski, Sandra M.

doi:10.1029/2005gl022878

Cited by 109 publications

(77 citation statements)

References 10 publications

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“…The Rayleigh wave dispersion curve was estimated by the Extended Spatial Auto Correlation (ESAC) method (Aki 1957;Ohori (Bergamo et al 2011). Rayleigh wave dispersion and H/V ratio curves were used to estimate the local S-wave velocity profile, using a joint inversion scheme (Arai and Tokimatsu 2005;Parolai et al 2005;Picozzi et al 2005), under the assumption of vertically heterogeneous 1D Earth models. The validity of this assumption was investigated by computing the H/V curve for each station of the array using the recorded data, and checking their similarity.…”

Section: Vs Vpmentioning

confidence: 99%

Site effects observed in alluvial basins: the case of Norcia (Central Italy)

Bindi

Luzi

Parolai

et al. 2011

Bull Earthquake Eng

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In this work, we investigate the site amplification effects observed in the Norcia plain, Central Italy. Data from 30 selected local earthquakes (2 ≤ Ml ≤ 4.1) recorded by a temporary seismic network composed by 15 stations, are analyzed to determine the spatial variability of site effects. Both the Horizontal-to-Vertical spectral ratio and the Standard Spectral Ratio techniques are applied to estimate the site amplification effects. The results show that most of the sites in the valley are affected by strong amplifications (up to a factor of 20) in the frequency range 0.5-5 Hz. The value of the fundamental frequency of resonance is strictly dependent on the location within the basin and on the sediment thickness. Strong amplifications also affect the vertical components. The time-frequency analysis performed on a station located inside the basin shows the presence of a large spectral amplitudes after the S-wave phase, not observed on a station located on the bedrock, suggesting the presence of locally generated wave trains. Then, in agreement with earlier observations for other alluvial basins in Central Italy, 2D-3D effects play an important role in determining the site amplification effects in Norcia.

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Section: Vs Vpmentioning

confidence: 99%

Site effects observed in alluvial basins: the case of Norcia (Central Italy)

Bindi

Luzi

Parolai

et al. 2011

Bull Earthquake Eng

View full text Add to dashboard Cite

show abstract

“…Furthermore, a selection criterion is included by considering only interstation distances less than twice the wavelength of the grid-search procedure. Once the phase velocities have been constrained, a joint inversion Picozzi et al 2005), which combines the results of the dispersion curve and H/V estimates, is applied in order to retrieve S-wave velocity profiles. Different parametrizations of the velocity model were tested, and finally we selected 4-6 layers in order to avoid overparametrization.…”

Section: Data S E T Smentioning

confidence: 99%

Shear wave velocity versus quality factor: results from seismic noise recordings

Boxberger¹,

Pilz²,

Parolai

2017

Geophysical Journal International

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S U M M A R YThe assessment of the shear wave velocity (v s ) and shear wave quality factor (Q s ) for the shallow structure below a site is necessary to characterize its site response. In the past, methods based on the analysis of seismic noise have been shown to be very efficient for providing a sufficiently accurate estimation of the v s versus depth at reasonable costs for engineering seismology purposes. In addition, a slight modification of the same method has proved to be able to provide realistic Q s versus depth estimates. In this study, data sets of seismic noise recorded by microarrays of seismic stations in different geological environments of Europe and Central Asia are used to calculate both v s and Q s versus depth profiles. Analogous to the generally adopted approach in seismic hazard assessment for mapping the average shear wave velocity in the uppermost 30 m (v s30 ) as a proxy of the site response, this approach was also applied to the quality factor within the uppermost 30 m (Q s30 ). A slightly inverse correlation between both parameters is found based on a methodological consistent determination for different sites. Consequently, a combined assessment of v s and Q s by seismic noise analysis has the potential to provide a more comprehensive description of the geological structure below a site.

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“…As an example, since 1-D seismic profiles built from the analysis of surface waves are non-unique because they are built from a non-linear inverse problem, the resolution of such profiles is limited (Picozzi et al 2005;Foti et al 2009;Comina et al 2011). On the contrary, the resolution of 1-D seismic profiles depends on the distance between acquisitions points with borehole measurements that can be averaged to get smooth variations (Moss 2008).…”

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confidence: 99%

Influence of a sedimentary basin infilling description on the 2-D P–SV wave propagation using linear and non-linear constitutive models

Gelis¹,

Bonilla

2014

Geophysical Journal International

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S U M M A R YNumerical modelling is a useful tool to understand the role of different parameters (site geometry, impedance contrast, material properties, constitutive model, input motion) governing site effects. We focus here on the 2-D P-SV seismic wave propagation in a simple-shaped asymmetric model. We consider two ways of describing the sedimentary infilling properties: the basin is either composed of distinct homogeneous geological layers or is described through properties progressively changing as a function of depth (smooth model). In order to study the wave propagation in the two basins with similar soil properties, P and S velocities of the layered basin are deduced from the smooth basin ones, making both models compatible in a kinematic point of view. P and S velocities globally increase with depth. Following EPRI, non-linear properties are considered as constant in layers for the two basins. We assess the influence of the model choice on the wave propagation while taking into account linear and non-linear constitutive models. We test the influence of the input motion by propagating two different input motions, the first being a simple impulsive one and the second a real complex accelerogram. We find that transfer functions computed in each basin are quite similar irrespective of the soil constitutive behaviour and the input motion. Moreover, we show that the maximum shear strain spatial distribution depends on the input motion frequency content and maximum values depend on the input motion strength and complexity. Maximum shear strains are generally higher for superficial layers than for deeper ones. We show that the highest shear strain values are located above discontinuities, where velocities are lower and the soil is more non-linear than in the underlying layer, regardless of the input motion. Indeed, in a layered basin, the shear strain is higher above interfaces for all the soil constitutive models that were used. In the smooth visco-elastoplastic model, a kind of layering appears, absent in a viscoelastic model, due to the different non-linear properties in each layer. Moreover, no matter what the model structure and the input motion used, maximum shear strain levels are higher in the visco-elastoplastic soil than in the viscoelastic one. Such a numerical study helps to understand the non-linearity location and therefore the consequences of a model choice when performing a site-specific study.

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Joint inversion of H/V ratios and dispersion curves from seismic noise: Estimating the S‐wave velocity of bedrock

Cited by 109 publications

References 10 publications

Site effects observed in alluvial basins: the case of Norcia (Central Italy)

Site effects observed in alluvial basins: the case of Norcia (Central Italy)

Shear wave velocity versus quality factor: results from seismic noise recordings

Influence of a sedimentary basin infilling description on the 2-D P–SV wave propagation using linear and non-linear constitutive models

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