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1.
Evaluation of the influence of experimental conditions on H/V results from ambient noise recordings 总被引：5，自引：2，他引：3
Jean-Luc Chatelain Bertrand Guillier Fabrizio Cara Anne-Marie Duval Kuvvet Atakan Pierre-Yves Bard 《Bulletin of Earthquake Engineering》2008,6(1):33-74
The H/V-noise technique is now widely used to estimate site effect parameters (fundamental frequency and sometimes the associated soil amplification), and many surveys using this technique have provided convincing results. However, a general agreement on a methodology for data acquisition, data processing and result interpretation has yet to be found. H/V measurements from ambient noise recordings imply both reliability of the results and rapidity of data collection. It is therefore important to understand which experimental conditions (1) influence data quality and reliability, and (2) can help speeding up the recording process. Within the framework of the SESAME European project, a specific task was defined to investigate the reliability of the H/V spectral ratio technique in assessing the site effects. The aim of WP02, one specific Work Package of the SESAME project, is to study the effects of experimental conditions on both stability and reproducibility of H/V results. This study has been conducted in a purely experimental way, by testing the possible influence of various experimental conditions on H/V results both on the frequency peak value and on its amplitude. WP02 results help setting up the experimental conditions under which ambient noise recordings have to be performed in order to provide reproducible, reliable and meaningful H/V results. In this paper we present the results of the WP02 SESAME project concerning the evaluation of the influence of experimental conditions of ambient noise recording on H/V results. 相似文献
2.
Abd el-aziz Khairy Abd el-aal 《Journal of Seismology》2018,22(5):1315-1323
In this contribution, new relationship between the fundamental site frequency and the thickness of soft sediments is obtained for many sites in Egypt. The Horizontal-to-Vertical Spectral Ratio (“H/V”) technique (known as Nakamura technique) can be used as a robust tool to determine the thickness of soft sediments layers overlaying bedrock from observations and measurements of seismic ambient noise data. In Egypt, numerous seismic ambient noise measurements have been conducted in several areas to determine the dynamic properties of soft soil for engineering purposes. At each site in each studied area, the fundamental site frequency was accurately estimated from the main peak in the spectral ratio between the horizontal and vertical component. Consequently, an extensive database of microtremor measurements, well logging data, and shallow seismic refraction data have been configured and assembled for the studied areas. New formula between fundamental site frequency (f0) and thickness of soft sediments (h) is established. The new formula has been validated and compared with other formulas of earlier scientists, and the results indicate that the calculated depth and geometry of the bedrock surface using new formula are in a good agreement with well logs data and previously published seismic refraction surveys in the investigated sites. 相似文献
3.
Empirical evaluation of microtremor H/V spectral ratio 总被引：6，自引：2，他引：4
The objective of this work is to perform a purely empirical assessment of the actual capabilities of the horizontal-to-vertical (H/V) spectral ratio technique to provide reliable and relevant information concerning site conditions and/or site amplification. This objective has been tackled through the homogeneous (re)processing of a large volume of earthquakes and ambient noise data recorded by different research teams in more than 200 sites located mainly in Europe, but also in the Caribbean and in Tehran. The original recordings were first gathered in a specific database with information on both the sites and recorded events. Then, for all sites close to an instrumented reference, average site-to-reference spectral ratios (“spectral ratio method” (SSR)) were derived in a homogeneous way (window selection, smoothing, signal-to-noise ratio threshold, averaging), as well as H/V ratios (“HVSRE–RF”) on earthquake recordings. H/V ratios were also obtained from noise recordings at each site (either specific measurements, or extracted from pre- or post-event noise windows). The spectral curves resulting from these three techniques were estimated reliable for a subset of 104 sites, and were thus compared in terms of fundamental frequency, amplitude and amplification bandwidth, exhibiting agreements and disagreements, for which interpretations are looked for in relation with characteristics of site conditions. The first important result consists in the very good agreement between fundamental frequencies obtained with either technique, observed for 81% of the analyzed sites. A significant part of the disagreements correspond to thick, low frequency, continental sites where natural noise level is often very low and H/V noise ratios do not exhibit any clear peak. The second important result is the absence of correlation between H/V peak amplitude and the actual site amplification measured on site-to-reference spectral ratios. There are, however, two statistically significant results about the amplitude of the H/V curve: the peak amplitude may be considered as a lower bound estimate of the actual amplification indicated by SSR (it is smaller for 79% of the 104 investigated sites), and, from another point of view, the difference in amplitude exhibits a questioning correlation with the geometrical characteristics of the sediment/basement interface: large SSR/HV differences might thus help to detect the existence of significant 2D or 3D effects. 相似文献
4.
基于四川石棉县安顺场隐伏断层穿越区的60余次环境噪声测试,探讨了隐伏断层对环境噪声H/V谱比特征的影响,并且通过研究区所获卓越频率对其覆盖层厚度进行估算,以覆盖层厚度的变化揭示了隐伏断层的行迹。结果显示:① 在排除可能受河流影响引发的高频区后,隐伏断层带处的H/V谱比曲线多呈现高频、低放大系数和多峰值频率等特点;② 覆盖层厚度在部分强风化区和河流高频区存在5—10 m的差异;③ 环境噪声阵列反演所得部分覆盖层厚度变化较大区域与隐伏断层的形迹吻合。 相似文献
5.
Tereza Šindelárová Michal Kozubek Jaroslav Chum Kateřina Potužníková 《Studia Geophysica et Geodaetica》2016,60(4):747-762
Infrasound environments in the Czech microbarograph network were studied. Reference Fourier amplitude spectra were calculated from data measured at three microbarograph sites of the network in May 2011-April 2012; directional analysis of infrasound arrivals in the frequency band 0.15-0.4 Hz was performed for the microbarograph array at Panská Ves in May 2014-April 2015. Diurnal, seasonal and site-to-site variability of the reference spectra was evaluated. Site-to-site variability is influenced by the location of the respective sensors in the open air and inside the observatory buildings and by local noise phenomena like wind turbines. Diurnal variability is well developed in summer with maximum ambient noise levels during the daytime and minima at night. Seasonal variability is observed at night with maxima in winter and minima in summer. Wind and wind eddies seem to be an important source of ambient noise in measurements in the Czech microbarograph network. A distinct spectral peak occurs near 0.2 Hz with amplitudes by about one order of magnitude higher in winter than in summer. Its seasonal variability is related to seasonal propagation of microbaroms from the source region in the Northern Atlantic. 相似文献
6.
Nikolaos Theodoulidis Giovanna Cultrera Valerio De Rubeis Fabrizio Cara Areti Panou Marco Pagani Paula Teves-Costa 《Bulletin of Earthquake Engineering》2008,6(1):109-140
In the framework of the SESAME project one of the tasks was the compilation of all available ambient noise measurements within urban environments affected by historical or/and recent strong earthquakes in Europe. The aim of such a task was to give an answer to the question; “How does horizontal-to-vertical ambient noise spectral ratio compare with damage in modern cities?”. For this purpose five European urban areas, namely, Angra do Heroismo (Portugal), Fabriano and Palermo (Italy), Thessaloniki and Kalamata (Greece) were selected for which spatial damage information was available either in terms of modified Mercalli intensity or in EMS98 damage grades. The geological setting of the examined sites as well as the causative earthquakes are satisfactorily known. Ambient noise recordings compiled for all examined sites have been homogeneously processed by a technique developed and agreed upon SESAME project. Using a standard multivariate statistical analysis, namely, factor analysis and canonical correlation, the horizontal-to-vertical ambient noise spectral ratio (HVNSR) is correlated with damage pattern observed within examined urban areas. Results show that, in some cases (Thessaloniki, Palermo), the HVNSR seems to be able to differentiate between areas previously shown to be associated with higher damage. In other cases however (Angra do Heroismo, Fabriano, Kalamata), the correlation is not statistically significant indicating thus the complex character of the parameters involved, implying that currently there is no a straightforward way that a value of HVNSR can correctly predict the extent to which a given region will be associated with increased damage. 相似文献
7.
8.
Brigitte Endrun 《Journal of Seismology》2011,15(3):443-472
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. 相似文献
9.
Local geology or local site effect is a crucial component while conducting seismic risk assessment studies. Investigations made by utilization of ambient noise are an effective tool for local site estimation. The present study is conducted to perform site response analysis at 13 different sites within urban settlements of Fateh jang area(Pakistan). The aim of this study was achieved by utilizing Nakamura method or H/V spectral ratio method. Some important local site parameters, e.g., the fundamental frequencies f0 of soft sediments, amplitudes A0 of corresponding H/V spectral ratios, and alluvium thicknesses over 13 sites within the study area, were measured and analyzed. The results show that the study area reflects low fundamental frequency f0. The fundamental frequencies of the sediments are highly variable and lie in a range of 0.6–13.0 Hz. Similarly, amplification factors at these sites are in the range of 2.0–4.0. 相似文献
10.
Past and recent observations have shown that the local site conditions significantly affect the behavior of seismic waves and its potential to cause destructive earthquakes. Thus, seismic microzonation studies have become crucial for seismic hazard assessment, providing local soil characteristics that can help to evaluate the possible seismic effects. Among the different methods used for estimating the soil characteristics, the ones based on ambient noise measurements, such as the H/V technique, become a cheap, non-invasive and successful way for evaluating the soil properties along a studied area.In this work, ambient noise measurements were taken at 240 sites around the Doon Valley, India, in order to characterize the sediment deposits. First, the H/V analysis has been carried out to estimate the resonant frequencies along the valley. Subsequently, some of this H/V results have been inverted, using the neighborhood algorithm and the available geotechnical information, in order to provide an estimation of the S-wave velocity profiles at the studied sites.Using all these information, we have characterized the sedimentary deposits in different areas of the Doon Valley, providing the resonant frequency, the soil thickness, the mean S-wave velocity of the sediments, and the mean S-wave velocity in the uppermost 30 m. 相似文献
11.
The Algiers–Boumerdes regions were hit by an M w 6.8 destructive earthquake on May 21, 2003. The accelerometric and seismometric networks successfully recorded the main shock and many aftershocks at some locations where the damage was most extensive. A microtremor measurement was performed in the same locations; some of them are localized on the Mitidja basin. In this paper, we propose to analyze earthquake-induced site effect derived from horizontal to vertical spectral ratio from ambient noise (noise horizontal to vertical—NHV), or from very weak, weak, moderate and strong ( peak ground acceleration—PGA >10 % g) seismic motions (EHV), and transfer function evaluation from soil velocity profile data at four sites. H/V spectral ratios are computed by using both Fourier and response spectra. Compared to the transfer function, the obtained results show that in the case of soft soils, NHV as well as EHV give a good estimation of the soil's fundamental frequency, whereas the NHV underestimate the H/V amplitude and the EHV amplitude increase with the seismic motion intensity. In the case of firm soils, whereas the NHV gives flat curves synonymous for a rock site or a bump, the EHV is more appropriate as seen by identifying clear peaks with non negligible amplitude. In the case of soft sites as well as in the case of firm sites, strong peaks at frequencies higher than the fundamental one are found from EHV curves. Those peaks would not be found when looking at NHV ratios alone, are evidenced by the computed transfer function as well as by an analytical formulation, and are in agreement with the observed distribution of damage during the M w 6.8 2003 Boumerdes earthquake. Finally, the same analysis is performed by using response spectra rather than Fourier spectra and leads to the same conclusions. Moreover, the calculation of the response spectra is more easily compared with the smoothing operation of the Fourier spectra. 相似文献
12.
Microearthquake recordings of local events have been used to quantify the site effects in the vicinity of Bursa City, northwest Turkey. Since the city is located near the southwest branch of the western extension of the North Anatolian Fault (NAF) zone, the importance of the seismic hazard in the region becomes progressively more important. The accelerograms of 69 earthquakes that were recorded on different geologic units, massive limestone, slope deposit and Quaternary sediment were analyzed to estimate the response of the recording sites. Site amplification functions were obtained by using three different approaches (standard spectral ratio, SSR; horizontal to vertical, H/V ratio and generalized inversion method, GIM) and the differences between the methods were also evaluated. We found large discrepancies between the SSR and H/V ratio methods, specifically; the former yields almost three times higher amplitudes than those obtained in the latter approach. Station located within the Bursa Quaternary basin (SCKR) is characterized by the largest estimates of the amplification amplitudes (8.0, 4.5 and 4.0 for SSR, H/V ratio and GIM, respectively) in all the three methods. On the other hand, stations located on deep limestone geological unit (SIGD and SKAY) show the least amplification level, ranging between 1.0 and 1.6. Three methods are able to identify resonant frequencies of the sites, although the absolute amplitudes of the amplification function are obtained different from each method. 相似文献
13.
Hadi Ghofrani Gail M. Atkinson Katsuichiro Goda 《Bulletin of Earthquake Engineering》2013,11(1):171-203
Site response in Japan is characterized using thousands of surface and borehole recordings from events of moment magnitude $(\mathbf{M}) > 5.5$ collected by the KiK-net network, including the 2011 M9.0 Tohoku earthquake. Site amplification is defined by the ratio of motions at the surface to those at depth (within the borehole), corrected for the depth effect due to destructive interference using a technique based on cross-spectral ratios between surface and down-hole motions. Site effects were particularly strong at high frequencies, despite the expectation that high-frequency response may be damped by nonlinear effects. In part, the large amplitudes at high frequencies are due to the prevalence of shallow soil conditions in Japan. We searched for typical symptoms for soil nonlinearity, such as a decrease in the predominant frequency and/or amplification, using spectral ratios of weak to strong ground motions. Localized nonlinearity occurred at some recording sites, but was not pervasive. We developed a general empirical model to express site amplification for the KiK-net sites as a function of common site variables, such as the average shear-wave velocity in the uppermost 30 m ( $\text{ V}_\mathrm{S30})$ and the horizontal-to-vertical (H/V) spectral ratio. We use the model to estimate site-corrected ground-motions for the Tohoku mainshock for a reference site condition; these motions are in reasonable agreement with the predictions of some of the published ground motion prediction equations for subduction zones. 相似文献
14.
Analysis of ambient noise in Yalova, Turkey: discrimination between artificial and natural excitations 总被引：2，自引：2，他引：0
Ambient noise measurements acquired in Yalova, which was highly damaged during the 1999 Izmit earthquake, are analyzed to explore the site characteristics. The region of Yalova is governed by complex geological and geomorphological structures consisting of river beds extending from the mountains to the sea, ridges between them, plains in front of them with different size, and the sea coast. As a result of these shallow geological features, the H/V curves exhibit complex patterns. Clear peaks in the H/V curves, which can be interpreted as reliable site resonance frequency, are observed only at about half of the measurement sites. At the remaining sites industrial peaks, broad peaks, or flat responses dominate the spectral ratio graphs. We observed that man-made noises generated by marble cutting machines in Hersek delta mask the site resonance frequencies or can be misinterpreted as a resonance frequency. In total, we identified three anthropogenic noise sources at fundamental frequencies of 1.3, 1.5, and 1.7 Hz along with their two- and threefold harmonics. The parts of H/V curves showing unusual low scattering can be a clue to identify anthropogenic effects. In the assessment of H/V curves, the site location and the similarity of the near surface geology were taken into account. The Laledere plain with thick and soft sediment sequence surprisingly displays flat responses due to a possible low impedance contrast. The Ciftlikkoy and Hacimehmet plains exhibit clear resonance peaks at nearly 1 Hz possessing the largest amplitudes. These sites experienced the highest damage in Yalova during the Izmit earthquake. In contrast, the Cinarcik region which was also exposed to high damage, do not show any obvious amplifications on the H/V curves. Generally, the H/V curves for valley and ridge sites in Yalova reveals a resonance peak at approximately 1 Hz and almost flat curves, respectively. However, several sites on the ridges and valleys portray different patterns. 相似文献
15.
Stefano Parolai Gottfried Grünthal Rutger Wahlstrm 《Soil Dynamics and Earthquake Engineering》2007,27(1):49-59
Seismic noise was measured at some 20 sites in the Cologne area (Germany) aligned nearly perpendicular to a graben structure. The H/V spectral noise ratio for each site was used to derive realistic S-wave velocity profiles down to the bedrock by means of a genetic algorithm inversion. Numerical simulations were performed for different combinations of source and propagation path parameters: focal depth, epicentral distance, attenuation and fault mechanism. Synthetic seismograms were produced and converted to Fourier and response spectra. Finally, the site-specific values from response spectral ratios, with their uncertainties, were used to modify attenuation functions entering the logic-tree algorithm of the probabilistic seismic hazard assessment (PSHA). The site-specific response spectra show the significance of taking into account the local S-wave velocity structure in PSHA. 相似文献
16.
The reference spectral noise ratio method to evaluate the seismic response of a site 总被引：2，自引：0，他引：2
The seismic response of several sites in the Durban area of South Africa has been investigated using a refined version of the spectral ratio (H/V) generated by cultural seismic noise. Two samples of noise separated by an interval of several minutes for the vertical and the two orthogonal horizontal components were taken at each site. Though the two samples differed noticeably in the time as well as in the frequency domain, when the components are considered separately, the ratios of the horizontal to the vertical spectra were very similar for most of the pairs. This similitude was obvious not only in the frequencies of the peaks, but also in the range of amplifications involved. These observations have been used to introduce a refinement to the Nakamura Method. This refinement consists in using as a reference the H/V spectral ratio of a well-known, hard rock site. All the other soft sites of interest are then compared with this standard reference site. This comparison provides valuable information on the frequencies and amplification factors introduced by the critical soft sediments. This refined method will be referred here as the ‘Reference spectral noise ratio’.This method, is compared to a similar one devised to investigate the response of horizontal layers to longitudinal seismic waves, using the ratio of the spectra generated by long- period waves. 相似文献
17.
Nasser Laouami Mohamed Hadid Noureddine Mezouar 《Bulletin of Earthquake Engineering》2018,16(12):5843-5874
Nowadays, most of the site classifications schemes are based on the predominant period of the site as determined from the average horizontal to vertical spectral ratios of seismic motion or microtremor. However, the difficulty lies in the identification of the predominant period in particular if the observed average response spectral ratio does not present a clear peak but rather a broadband amplification or multiple peaks. In this work, based on the Eurocode-8 (2004) site classification, and assuming bounded random fields for both shear and compression waves-velocities, damping coefficient, natural period and depth of soil profile, one propose a new site-classification approach, based on “target” simulated average \( H/V \) spectral ratios, defined for each soil class. Taking advantage of the relationship of Kawase et al. (Bull Seismol Soc Am 101:2001–2014, 2011), which link the \( H/V \) spectral ratio to the horizontal (\( HTF \)) over the vertical (\( VTF \)) transfer functions, statistics of \( H/V \) spectral ratio via deterministic visco-elastic seismic analysis using the wave propagation theory are computed for the 4 soil classes. The obtained results show that \( H/V \) and \( HTF \) have amplitudes and shapes remarkably different among the four soil classes and exhibit fundamental peaks in the period ranges remarkably similar. Moreover, the “target” simulated average \( H/V \) spectral ratios for the 4 soil classes are in good agreement with the experimental ones obtained by Zhao et al. (Bull Seismol Soc Am 96:914–925, 2006) from the abundant and reliable Japanese strong motions database Kik-net, Ghasemi et al. (Soil Dyn Earthq Eng 29:121–132, 2009) from the Iranian strong motion data, and Di Alessandro et al. (Bull Sesismol Soc Am 106:2, 2011. https://doi.org/10.1785/0120110084) from the Italian strong motion data. In addition to the 4 EC-8 standard soil classes (A, B, C and D), the superposition of the 4 target \( H/V \) reveals 3 new boundary site classes; AB, BC and CD, for overlapping \( V_{s,30} \) ranges when the predominant peak is not clearly consistent with any of the 4 proposed classes. Finally, one proposes a site classification index based on the ratio between the cross-correlation and the mean quadratic error between the in situ \( H/V \) spectral ratio and the “target” one. In order to test the reliability of the proposed approach, data from 139 sites were used, 132 collected from the Kik-net network database from Japan and 7 from Algeria. The site classification success rate per site class are around 93, 82, 89 and 100% for rock, hard soil, medium soil and soft soil, respectively. Zhao et al. (2006) found an average success for the 4 classes of soil close to 60%, similar to what one found in the present study (63%) without considering the new soil classes, but much smaller if one considers them (86%). In the absence of \( V_{s,30} \) data, the proposed approach can be an alternative to site classification. 相似文献
18.
R. Maresca M. Castellano R. De Matteis G. Saccorotti P. Vaccariello 《Pure and Applied Geophysics》2003,160(9):1745-1764
19.
Rosalba Maresca Norma Damiano Lucia Nardone Mauro A. Di Vito Francesca Bianco 《Journal of Seismology》2014,18(3):385-400
In this study, we describe two experiments of seismic noise measurements carried out in Naples, Italy. The site allowed measurements to be obtained both at the surface and in a tunnel that is 120-m-deep. The main goal was to compare the seismic response evaluated at the surface to the in-tunnel response, through spectral, polarization, and resonance directivity analyses. In the 1 to 20 Hz frequency band, the noise level was up to 15 dB higher at the surface than in the tunnel. The polarization properties and horizontal-to-vertical spectral ratios appear not to be influenced by the tunnel geometry or by the topography. Some preferential alignments were observed in the polarization azimuths computed at the surface, which are likely to be due to local sources, rather than morphological features. The absence of directivity effects and the low noise levels in the tunnel make this site suitable for installing seismic stations. We also studied how the subsoil structure affects the seismic motion at the surface. The dispersive properties of the Rayleigh waves were investigated using the spatial autocorrelation method. A joint inversion of the dispersion data and the horizontal-to-vertical spectral ratios provided the subsurface Vs profile. The derived model has a low velocity contrast at depth, such as to generate moderate and broad H/V spectral ratio peak amplitude. The normalized spectral ratio appears more appropriate to identify the soil-resonance frequencies. 相似文献
20.
Microzonation studies using ambient noise measurements have become very popular in the last years for local soil characteristics determination. For defining the capabilities of the ambient noise based methods, a physical understanding of the nature of noise is essential. In this way, many studies have shown that the noise wavefield composition is heterogeneous, comprising both body and surface waves with fundamental and upper modes.In this work, a recently developed method of time-frequency polarization analysis, based on the stationary wavelet packet transform, is used to study how the waves’ polarization influences in the application of the HVSR method. For this purpose, each recorded signal is first decomposed into a set of sub-signals, according to their reciprocal ellipticity. After that, the H/V analysis is carried out on the raw recorded signal, as well as on the obtained sub-signals, evaluating the contribution of each sub-signal (i.e., each reciprocal ellipticity range) to the expected H/V result.For the study, single station seismic noise was recorded at 11 sites around the province of Alicante (southeastern Spain). The obtained results illustrate that high frequency peaks, above 1–2 Hz, are clearly represented by just using the sub-signals associated to the ellipticity range of [0–0.1], whereas low frequency peaks, down 0.5 Hz, need a wider ellipticity interval for being properly retrieved, i.e., [0–0.4] or even [0–0.6]. Therefore, linearly polarized waves’ contribution, range [0–0.1], is enough for retrieving the high frequency H/V peaks, but not for obtaining the complete H/V curve, especially the low frequency peaks. In these cases, the elliptical polarized Rayleigh waves’ contribution cannot be misestimated in HVSR computation. 相似文献