Seismic Soil Effect in an Embanked Deep Alpine Valley: A Numerical Investigation of Two-Dimensional Resonance

Frischknecht, Corine

doi:10.1785/0120020158

Cited by 28 publications

(19 citation statements)

References 17 publications

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“…15) that correspond to the fundamental resonance peak and to the frequency band associated with the lateral waves, respectively. In agreement with the numerical results obtained for different basin-like systems (Semblat et al, 2000(Semblat et al, , 2002aFrischknecht and Wagner, 2004), the low frequency related to the fundamental resonance results is increasingly amplified from the bottom to the top of the alluvial deposits, while on the contrary, the higher frequencies reach the maximum amplification values within the alluvial fill at about 20 m BGL. However, these focusing effects significantly decrease if nonlinear conditions are taken into account.…”

Section: Discussionsupporting

confidence: 90%

Evidence of Two-Dimensional Amplification Effects in an Alluvial Valley (Valnerina, Italy) from Velocimetric Records and Numerical Models

Lenti

Martino²,

Paciello

et al. 2009

Bulletin of the Seismological Society of America

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The results of field surveys, velocimetric records, and numerical models are reported with the goal of analyzing the local seismic response in a section of the Nera River alluvial valley in central Italy. Alluvial deposit geometry and dynamic properties were defined by geological and geophysical investigations. 2D amplification effects were pointed out by horizontal-to-vertical spectral ratios (HVSRs) as well as by horizontal-to-horizontal spectral ratios (HHSRs) to a reference station; HVSRs were derived from both noise and weak-motion records, while HHSRs were only computed from weak motions. Where travertine deposits are interlayered within the alluvia, 2D amplification effects are shown only by HHSRs. The observed amplifications: (1) consist of peaks of the amplification functions A (f) in the range 1-10 Hz, (2) generally correspond to two frequency ranges whose values mainly depend on the valley shaped ratio and on the local heterogenities of the alluvial deposits, and (3) can be regarded as due to a 1D resonance combined with lateral wave propagation. Numerical models via the finite difference method were performed by the Italian National Institute for Geophysics and Volcanology-Web Interface for Seismological Application and by the Fast Lagrangian Analysis of Continua codes. The obtained results: (1) show a good agreement with HHSRs, (2) prove that some 2D amplification effects are constrained by both the shape ratio of the valley and the heterogeneity of the alluvial deposits, (3) reveal focalization effects within the alluvial deposits strictly related to the shape of the valley, and (4) allow the comparison of the A(f) functions in both linear and nonlinear dynamic behavior and the computation of the shear strains due to ground motion within the alluvial deposits

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Section: Discussionsupporting

confidence: 90%

Evidence of Two-Dimensional Amplification Effects in an Alluvial Valley (Valnerina, Italy) from Velocimetric Records and Numerical Models

Lenti

Martino²,

Paciello

et al. 2009

Bulletin of the Seismological Society of America

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“…Similar to what is observed across sediment-filled valleys in numerical simulations (e.g., Bouchon 1985, Frischknecht andWagner 2004) and in real data (e.g., Tucker and King 1984, Roten et al 2006), we expect the resonance frequency for such a normal mode resonance to be approximately equal over the entire extent of the landslide body, regardless of its thickness at each site, alike Burjanek et al (2012). Using classical 1D transfer function theory and the obtained velocity model (e.g., for S13 and S20, see Figure 6) one might pre-estimate that a thickness of the lowvelocity body of around 30 to 35 m will correspond to a fundamental frequency of around 2.5 Hz.…”

Section: Discussionsupporting

confidence: 83%

Combining Seismic Noise Techniques for Landslide Characterization

Pilz

Parolai

Bindi

et al. 2013

Pure Appl. Geophys.

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The strong topographic relief and the presence of weakly consolidated sediments create favorable conditions for the development of landslides around the eastern rim of the Fergana Basin (Central Asia). In summer 2012, a field experiment employing small aperture seismic arrays was carried out on an unstable slope, using ambient vibration recordings. The aim of the study was to constrain the seismic response of a potential future landslide and to map

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“…The depth of the sediment–bedrock interface was extracted from analogue maps published by Frischknecht & Wagner (2004) and Rosselli (2001). Fig.…”

Section: Geophysical Settingmentioning

confidence: 99%

A comparison of observed and simulated site response in the Rhône valley

Roten

Fäh

Olsen

et al. 2008

Geophysical Journal International

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S U M M A R YSite effects in the city of Sion in the Rhône valley are analysed from weak motion signals recorded on a dense temporary array. We simulate the recorded events with a 3-D finite difference method for frequencies up to 4 Hz using a recently developed velocity model of the Sion basin.Site-to-reference Fourier spectral ratios are computed from 16 local and regional events. All sites exhibit amplification factors of up to 12 between 0.5 and 0.6 Hz, which can be reproduced by the numerical simulations. By rotating the weak motion to directions parallel and perpendicular to the valley axis, we show that this low-frequency amplification is caused by the SH 00 and SV 0 fundamental modes of 2-D resonance.Additional peaks of amplification can be observed at higher frequencies, with amplification factors of up to 20 at some sites.Application of the high-resolution frequency-wavenumber and the multiple signal characterization method to the vertical component of recorded and simulated signals show that edge-generated surface waves arriving from almost all directions dominate the wavefield at 1.25 and 2.50 Hz.Peak ground velocities computed from the simulated ground motion show interference patterns that depend strongly on the incidence direction, and the computed amplification of peak ground velocities are generally in agreement with the observations. We conclude that the complex 3-D geometry of the basin needs to be considered to evaluate site effects up to at least 2.5 Hz.

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Seismic Soil Effect in an Embanked Deep Alpine Valley: A Numerical Investigation of Two-Dimensional Resonance

Cited by 28 publications

References 17 publications

Evidence of Two-Dimensional Amplification Effects in an Alluvial Valley (Valnerina, Italy) from Velocimetric Records and Numerical Models

Evidence of Two-Dimensional Amplification Effects in an Alluvial Valley (Valnerina, Italy) from Velocimetric Records and Numerical Models

Combining Seismic Noise Techniques for Landslide Characterization

A comparison of observed and simulated site response in the Rhône valley

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