Possibility of Estimation for Amplificatoin Characteristics of Soil Deposits Based on Ratio of Horizontal to Vertical Spectra of Microtremors

Wakamatsu, Kunio; Yasui, Yukihiko

doi:10.3130/aijs.60.61_3

Cited by 16 publications

(8 citation statements)

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“…Since then, a large number of experiments (Lermo & Chavez‐Garcia 1993; Gitterman et al 1996; Seekins et al 1996; Fäh 1997) have shown that the H/V procedure can be successful applied for identifying the fundamental resonance frequency of sedimentary deposits. These observations were supported by several theoretical 1‐D investigations (Field & Jacob 1993; Lachet & Bard 1994; Lermo & Chavez‐Garcia 1994; Wakamatsu & Yasui 1996; Tokeshi & Sugimura 1998), that have shown that noise synthetics computed using randomly distributed, near surface sources lead to H/V ratios sharply peaked around the fundamental S ‐wave frequency, when the surface layer exhibits a sharp impedance contrast with the underlying stiffer formations. However, some discussions are still under way about the applicability of this technique to evaluating the site amplification (Bard 1998; Bour et al 1998; Mucciarelli 1998; Al Yuncha & Luzon 2000; Maresca et al 2003; Rodriguez & Midorikawa 2003).…”

Section: Introductionsupporting

confidence: 60%

H/V ratio: a tool for site effects evaluation. Results from 1-D noise simulations

Bonnefoy-Claudet

Cornou

Bard

et al. 2006

Geophysical Journal International

410

201

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National audienceAmbient vibration techniques such as the H/V method may have the potential to significantly contribute to site effect evaluation, particularly in urban areas. Previous studies interpret the so-called Nakamura's technique in relation to the ellipticity ratio of Rayleigh waves, which, for a high enough impedance contrast, exhibits a pronounced peak close to the fundamental S-wave resonance frequency. Within the European SESAME project (Site EffectS assessment using AMbient Excitations) this interpretation has been tested through noise numerical simulation under well-controlled conditions in terms of source type and distribution and propagation structure. We will present simulations for a simple realistic site (one sedimentary layer over bedrock) characterized by a rather high impedance contrast and low quality factor. Careful H/V and array analysis on these noise synthetics allow an in-depth investigation of the link between H/V ratio peaks and the noise wavefield composition for the soil model considered here: (1) when sources are near (4 to 50 times the layer thickness) and surficial, H/V curves exhibit one single peak, while the array analysis shows that the wavefield is dominated by Rayleigh waves; (2) when sources are distant (more than 50 times the layer thickness) and located inside the sedimentary layer, two peaks show up on the H/V curve, while the array analysis indicates both Rayleigh waves and strong S head waves; the first peak is due to both fundamental Rayleigh waves and resonance of head S waves, the second is only due to the resonance of head S waves; (3) when sources are deep (located inside the bedrock), whatever their distance, H/V ratio exhibit peaks at the fundamental and harmonic resonance frequencies, while array analyses indicate only non-dispersive body waves; the H/V is thus simply due to multiple reflections of S waves within the layer. Therefore, considering that experimental H/V ratio (i.e. derived from actual noise measured in the field) exhibit in most cases only one peak, we conclude that H/V ratio is (1) mainly controlled by local surface sources, (2) mainly due to the ellipticity of the fundamental Rayleigh waves. Then the amplitude of H/V peak is not able to give a good estimate of site amplification facto

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Section: Introductionsupporting

confidence: 60%

H/V ratio: a tool for site effects evaluation. Results from 1-D noise simulations

Bonnefoy-Claudet

Cornou

Bard

et al. 2006

Geophysical Journal International

410

201

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“…Nakamura (1988) proposed a method to consider horizontal-to-vertical spectral ratios (HVRs) of microtremors as site amplification factors of S waves above shallow underground structures. Wakamatsu and Yasui (1995) and Konno and Ohmachi (1998) support Nakamura's method by showing that HVRs for short-period microtremors agree with theoretical site amplification factors. On the other hand, Horike (1985) and Okada et al (1990) showed, based on array measurements of microtremors, that the vertical component of microtremors are mainly composed of Rayleigh waves.…”

Section: Introductionmentioning

confidence: 52%

Differences Between Site Characteristics Obtained From Microtremors, S-waves, P-waves, and Codas

Satoh¹,

Kawase²,

Matsushima³

2001

Bulletin of the Seismological Society of America

129

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We examine differences of empirical site characteristics among S waves, P waves, coda, and microtremors using records at 20 sites in and around the Sendai basin, Japan, and interpret the differences theoretically. At soft soil sites the horizontal-to-vertical spectral ratios (HVRs) for early P coda become different from HVRs for a P wave with increasing time and eventually converge on HVRs for microtremors. The HVRs for an S coda become similar to HVRs for microtremors with increasing time in the frequency range lower than 3 Hz at soft soil sites. By contrast, at a rock site and two hard soil sites, HVRs for S coda agree well with HVRs for an S wave. The soil-to-rock spectral ratios for horizontal (HHRs) and vertical (VVRs) components for early S coda are larger than those for an S wave at soft soil sites. When we use the deep sedimentary structures above the bedrock before Tertiary age, theoretical HVR for the fundamental mode of Rayleigh waves is consistent with observed HVR for microtremors and theoretical HVR for an obliquely incident SV wave is consistent with observed HVR for an S wave. Theoretical S-wave site amplification factor explains well observed HHR for S wave but does not coincide with HVR for microtremors. In general the frequencies of maximum peaks of HVRs for microtremors do not coincide with those of HVRs and HHRs for S wave. However, if we select HVRs with peak frequencies lower than 1 Hz and peak amplitudes larger than three, the peak frequencies of HVRs for microtremors roughly coincide with those of HVRs and HHRs for S wave. Even under these constraints, their amplitudes do not coincide with each other. Concerning coda, we conclude that the Rayleigh wave contamination in coda is significant in the frequency range lower than 3 Hz at soft soil sites.

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“…Many experiments (Beauval et al, 2003;Di Giacomo et al, 2005;Fäh, 1997;Gitterman et al, 1996;Gosar, 2007;Guillier et al, 2007;Lermo and Chávez-García, 1993;Mundepi and Kamal, 2006;Panou et al, 2005;Parolai and Galiana-Merino, 2006;Seekins et al, 1996) supported by several theoretical 1-D investigations (Bonnefoy-Claudet et al, 2006;Chatelain et al, 2008;Field and Jacob, 1995;Guillier et al, 2008;Lachet and Bard, 1994;Tokeshi and Sugimura, 1998;Wakamatsu and Yasui, 1996) have shown that ambient noise H/V spectral ratio is sharply packed around the fundamental S-wave frequency if the upper layers have a sharp impedance contrast with the underlying stiffer layers.…”

Section: H/v Methodsmentioning

confidence: 94%

Characterization of the sedimentary cover at the Himalayan foothills using active and passive seismic techniques

Mahajan

Galiana-Merino

Lindholm

et al. 2011

Journal of Applied Geophysics

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Possibility of Estimation for Amplificatoin Characteristics of Soil Deposits Based on Ratio of Horizontal to Vertical Spectra of Microtremors

Cited by 16 publications

References 0 publications

H/V ratio: a tool for site effects evaluation. Results from 1-D noise simulations

H/V ratio: a tool for site effects evaluation. Results from 1-D noise simulations

Differences Between Site Characteristics Obtained From Microtremors, S-waves, P-waves, and Codas

Characterization of the sedimentary cover at the Himalayan foothills using active and passive seismic techniques

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