Site condition evaluation using horizontal-to-vertical response spectral ratios of earthquakes in the NGA-West 2 and Japanese databases

Ghofrani, Hadi; Atkinson, Gail M.

doi:10.1016/j.soildyn.2014.08.015

Cited by 92 publications

(50 citation statements)

References 36 publications

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“…Overall, we observe that the spectral ratios are relatively flat between ~1 and 10 Hz and that spectral ratios tend to decrease for frequencies >10 Hz. As there is an observed inverse relationship between the frequency of amplification and the thickness of the layer that causes amplification [e.g., Ghofrani and Atkinson , ], the peak of the H / V spectral ratios at higher frequencies (~10 Hz) may be related to the velocity structure that consists of a thin layer of low‐velocity sediments overlying high‐velocity sedimentary rock and basement, like that observed in the 1‐D body wave velocity models of Keranen et al [] and Sumy et al []. We divide each of the horizontal event‐station amplitude spectra by the median H / V spectral ratio recorded at the corresponding station to aid in the removal of near‐surface site effects.…”

Section: Spectral Fitting Techniquementioning

confidence: 99%

“…The H / V spectral method assumes that the vertical component is relatively insensitive to site amplification compared to the horizontal component and thus can provide a first‐order estimate of site response [ Lermo and Chávez‐García, , ; Atkinson , ]. H / V spectral ratios likely reflect a first‐order estimate of site amplification and can include amplification due to a crustal velocity gradient and/or from a near‐surface soil or sediment layer [e.g., Bonilla et al , ; Ghofrani and Atkinson , ]. We examine the Fourier amplitude spectral ratio between the combined geometric mean of the horizontal spectra and the vertical spectra, respectively, for every event‐station pair (Figure S1).…”

Section: Spectral Fitting Techniquementioning

confidence: 99%

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Low stress drops observed for aftershocks of the 2011 M_w 5.7 Prague, Oklahoma, earthquake

et al. 2017

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In November 2011, three Mw ≥ 4.8 earthquakes and thousands of aftershocks occurred along the structurally complex Wilzetta fault system near Prague, Oklahoma. Previous studies suggest that wastewater injection induced a Mw 4.8 foreshock, which subsequently triggered a Mw 5.7 mainshock. We examine source properties of aftershocks with a standard Brune‐type spectral model and jointly solve for seismic moment (M0), corner frequency (f0), and kappa (κ) with an iterative Gauss‐Newton global downhill optimization method. We examine 934 earthquakes with initial moment magnitudes (Mw) between 0.33 and 4.99 based on the pseudospectral acceleration and recover reasonable M0, f0, and κ for 87 earthquakes with Mw 1.83–3.51 determined by spectral fit. We use M0 and f0 to estimate the Brune‐type stress drop, assuming a circular fault and shear‐wave velocity at the hypocentral depth of the event. Our observations suggest that stress drops range between 0.005 and 4.8 MPa with a median of 0.2 MPa (0.03–26.4 MPa with a median of 1.1 MPa for Madariaga‐type), which is significantly lower than typical eastern United States intraplate events (>10 MPa). We find that stress drops correlate weakly with hypocentral depth and magnitude. Additionally, we find the stress drops increase with time after the mainshock, although temporal variation in stress drop is difficult to separate from spatial heterogeneity and changing event locations. The overall low median stress drop suggests that the fault segments may have been primed to fail as a result of high pore fluid pressures, likely related to nearby wastewater injection.

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Section: Spectral Fitting Techniquementioning

confidence: 99%

Section: Spectral Fitting Techniquementioning

confidence: 99%

Low stress drops observed for aftershocks of the 2011 M_w 5.7 Prague, Oklahoma, earthquake

et al. 2017

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“…Subsequent studies found that, while the period of the HVSR peak coincides with the resonant period of S waves in the sediment column, the amplitude of the peak often does not match that of the S-wave transfer function (Lermo & Chavez-Garcia 1993;Lachet & Bard 1994;Bonilla et al 1997;Lunedei & Albarello 2010). Several studies have used HVSR to measure this resonant period in the range 0.1-2.0 s to infer site class (Zhao et al 2006;Ghofrani & Atkinson 2014) and to explain the spatial patterns of earthquake damage (Gosar 2010). HVSR measurements of resonant period have also been used to infer depth of sediments when velocity is known from, for example, surface wave dispersion (Ibst-von Seht & Wohlenberg 1999;D'Amico et al 2008) or average velocity when depth is known from geophysical surveys (Bodin et al 2001).…”

Section: H V S R M E a S U R E M E N T Smentioning

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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“…Moreover, V S30 does not capture all the underlying physics that control site amplification; thus, use of this parameter to describe site response has been the subject of debate (Anderson and others, 1996;Boore, 2004a;Mucciarelli and Gallipoli, 2006;Bragato, 2008;Castellaro and others, 2008;Lee and Trifunac, 2010). As a result, recent studies proposing new methods to account for site conditions have been published (Lee and Trifunac, 2010;Ghofrani and Atkinson, 2014). Until a new method is accepted, the engineering community will continue to use V S30 for the foreseeable future (Abrahamson and Shedlock, 1997;Abrahamson and others, 2008;Boore and others, 2011;Gregor and others, 2014).…”

Section: Introductionmentioning

confidence: 99%

Compilation of VS30 Data for the United States

Yong¹,

Thompson²,

Wald³

et al. 2016

Data Series

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Site condition evaluation using horizontal-to-vertical response spectral ratios of earthquakes in the NGA-West 2 and Japanese databases

Cited by 92 publications

References 36 publications

Low stress drops observed for aftershocks of the 2011 M_w 5.7 Prague, Oklahoma, earthquake

Low stress drops observed for aftershocks of the 2011 M_w 5.7 Prague, Oklahoma, earthquake

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

Compilation of <em>V</em><sub><em>S</em>30</sub> Data for the United States

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Site condition evaluation using horizontal-to-vertical response spectral ratios of earthquakes in the NGA-West 2 and Japanese databases

Cited by 92 publications

References 36 publications

Low stress drops observed for aftershocks of the 2011 Mw 5.7 Prague, Oklahoma, earthquake

Low stress drops observed for aftershocks of the 2011 Mw 5.7 Prague, Oklahoma, earthquake

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

Compilation of <em>V</em><sub><em>S</em>30</sub> Data for the United States

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Low stress drops observed for aftershocks of the 2011 M_w 5.7 Prague, Oklahoma, earthquake

Low stress drops observed for aftershocks of the 2011 M_w 5.7 Prague, Oklahoma, earthquake