Site Characterization of Strong‐Motion Recording Stations of Delhi Using Joint Inversion of Phase Velocity Dispersion and H/V Curve

Pandey, Bhavesh; Jakka, Ravi S.; Kumar, Ashok; Mittal, Himanshu

doi:10.1785/0120150135

Cited by 23 publications

(8 citation statements)

References 17 publications

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“…Profiling of velocity structure, sediment thickness and basin topography can also be accomplished via the joint inversion of HVSR and the surface wave dispersion curves, where the latter can be generated using autocorrelation (Claprood et al 2012) or multichannel analysis (Gorstein & Ezersky 2015;Pandey et al 2016). As shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Seismic velocity structure of the Jakarta Basin, Indonesia, using trans-dimensional Bayesian inversion of horizontal-to-vertical spectral ratios

Cipta

Cummins

Dettmer

et al. 2018

Geophysical Journal International

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Characterizing the interior structure of the Jakarta Basin, Indonesia, is important for the improvement of seismic hazard assessment there. A dense-portable seismic broad-band network, comprising 96 stations, has been operated between October 2013 and February 2014 covering the city of Jakarta. The seismic network sampled broad-band seismic noise mostly originating from ocean waves and anthropogenic activity. We used horizontal-to-vertical spectral ratio (HVSR) measurements of the ambient seismic noise to estimate fundamental-mode Rayleigh wave ellipticity curves, which were used to infer the seismic velocity structure of the Jakarta Basin. By mapping and modelling the spatial variation of low-frequency (0.124-0.249 Hz) HVSR peaks, this study reveals variations in the depth to the Miocene basement. These variations include a sudden change of basement depth from 500 to 1000 m along N-S profile through the centre of the city, with an otherwise gentle increase in basin depth from south to north. Higher frequency (2-4 Hz) HVSR peaks appear to reflect complicated structure in the top 100 m of the soil profile, possibly related to the sediment compaction and transitions among different sedimentary sequences. In order to map these velocity profiles of unknown complexity, we employ a trans-dimensional Bayesian framework for the inversion of HVSR curves for 1-D profiles of velocity and density beneath each station. Results show that very low-velocity sediments (<240 m s −1) up to 100 m in depth cover the city in the northern to central part, where alluvial fan material is deposited. These low seismic velocities and the very thick sediments in the Jakarta Basin will potentially contribute to seismic amplification and basin resonance, especially during giant megathrust earthquakes or large earthquakes with epicentres close to Jakarta. Results have shown good correlation with previous ambient seismic noise tomography and microtremor studies. We use the 1-D profiles to create a pseudo-3-D model of the basin structure which can be used for earthquake hazard analyses of Jakarta, a megacity in which highly variable construction practices may give rise to high vulnerability. The methodology discussed can be applied to any other populated city situated in a thick sedimentary basin.

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Section: Discussionmentioning

confidence: 99%

Seismic velocity structure of the Jakarta Basin, Indonesia, using trans-dimensional Bayesian inversion of horizontal-to-vertical spectral ratios

Cipta

Cummins

Dettmer

et al. 2018

Geophysical Journal International

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“…The sites used in this study belong to NEHRP site classes C and D. For this study, these sites were further divided into six groups in terms of VS,30 and depth of engineering bedrock (EB) (EB is considered as the first layer which has VS greater than 760 m/s) as follows; 235 The details of sites belonging to the Indian strong motion network and Japanese network are 242 presented in Table 1 and Table 2. 243 VS profiles of the Indian sites are obtained from the available literature (Pandey et al 2016(Pandey et al , 2021, and Kik-Net sites are obtained from the webpage http://www.kyoshin.bosai.go.jp, which were used for ground response analysis. Multiple ground response analysis was performed for each site using VS profiles up to different depths extracted from the original VS profile (Figure 1) to study the bedrock effect.…”

Section: Site Classification and Analysismentioning

confidence: 99%

Selection of an Appropriate Bedrock for Site Amplification Studies.

Pandey

Jakka

2021

Preprint

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The selection of half-space or reference sites significantly influences site amplification studies. However, there are no well-defined guidelines in the literature. Generally, a layer with a local shear wave velocity (VS) of more than 760 m/s is considered a bedrock/half-space/reference site. This study attempts to formulate a rationale for selecting bedrock stiffness to be used as a half-space/reference site. For this study, VS,30 (average shear wave velocity of top 30-meter soil strata from shear wave velocity measurements) and the site's fundamental frequency (obtained from Horizontal to vertical spectral ratio of ambient vibration records) were used as proxies to study the influence of bedrock/half-space and development of a rationale for their selection. This study uses strong-motion data from India's sixty-two strong motion stations and a few from Japan (Kik-Net). The results suggest that considering a site with a shear wave velocity of 760 m/s may not be suitable as a half-space/bedrock for most geomorphological conditions. The results also recognize a pattern that can help in the development of a mathematical model for determining the bedrock for a site using VS,30 and its fundamental frequency as a proxy.

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“…This study attempts to formulate a rationale for estimating a value that can be used as a Half-space/Reference site (in terms of VS) for a particular site depending upon proxies such as VS,30 and fundamental frequency obtained from Horizontal to Vertical spectral ratio of ambient vibration record. Available data from 62 stations of Indian strong-motion networks (Pandey et al 2016(Pandey et al , 2021and a few Japanese Kik-Net stations are used for this study.…”

Section: Introductionmentioning

confidence: 99%

Selection of an appropriate bedrock for site amplification studies

Pandey

Jakka

2022

Nat Hazards

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The selection of half-space or reference sites significantly influences site amplification studies. However, there are no well-defined guidelines in the literature. Generally, a layer with a local shear wave velocity (VS) of more than 760 m/s is considered a bedrock/halfspace/reference site. This study attempts to formulate a rationale for selecting bedrock stiffness to be used as a half-space/reference site. For this study, VS,30 (average shear wave velocity of top 30-meter soil strata from shear wave velocity measurements) and the site's fundamental frequency (obtained from Horizontal to vertical spectral ratio of ambient vibration records) were used as proxies to study the influence of bedrock/half-space and development of a rationale for their selection. This study uses strong-motion data from India's sixty-two strong motion stations and a few from Japan (Kik-Net). The results suggest that considering a site with a shear wave velocity of 760 m/s may not be suitable as a half-space/bedrock for most geomorphological conditions. The results also recognize a pattern that can help in the development of a mathematical model for determining the bedrock for a site using VS,30 and its fundamental frequency as a proxy.

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Site Characterization of Strong‐Motion Recording Stations of Delhi Using Joint Inversion of Phase Velocity Dispersion and H/V Curve

Cited by 23 publications

References 17 publications

Seismic velocity structure of the Jakarta Basin, Indonesia, using trans-dimensional Bayesian inversion of horizontal-to-vertical spectral ratios

Seismic velocity structure of the Jakarta Basin, Indonesia, using trans-dimensional Bayesian inversion of horizontal-to-vertical spectral ratios

Selection of an Appropriate Bedrock for Site Amplification Studies.

Selection of an appropriate bedrock for site amplification studies

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