Interfrequency Correlations among Fourier Spectral Ordinates and Implications for Stochastic Ground‐Motion Simulation

Stafford, Peter J.

doi:10.1785/0120170081

Cited by 26 publications

(33 citation statements)

References 41 publications

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“…Although the physical explanation of the magnitude dependence of between-event residuals has not been thoroughly explored, Kotha et al (2017) suggests that earthquakes with large magnitude and low corner frequency f c will likely result in high Sa correlations at frequencies above f c . Similar observations were made by Stafford (2017), who developed an inter frequency correlation model for Fourier spectral ordinates; this study found that between-event correlations have a mild dependence on earthquake magnitude.…”

Section: Introductionsupporting

confidence: 71%

Correlations of spectral accelerations in the Chilean subduction zone

et al. 2020

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The correlation between spectral accelerations is key in the construction of conditional mean spectra, the computation of vector-valued seismic hazard, and the assessment of seismic risk of spatially distributed systems, among other applications. Spectral correlations are highly dependent on the earthquake database used, and thus, region-specific correlation models have been developed mainly for earthquakes in western United States, Europe, Middle East, and Japan. Correlation models based on global data sets for crustal and subduction zones have also become available, but there is no consensus about their applicability on a specific region. This study proposes a new correlation model for 5% damped spectral accelerations and peak ground velocity in the Chilean subduction zone. The correlations obtained were generally higher than those observed from shallow crustal earthquakes and subduction zones such as Japan and Taiwan. The study provides two illustrative applications of the correlation model: (1) computation of conditional spectra for a firm soil site located in Santiago, Chile and (2) computation of bivariate hazard for spectral accelerations at two structural periods.

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Section: Introductionsupporting

confidence: 71%

Correlations of spectral accelerations in the Chilean subduction zone

et al. 2020

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“…Therefore, we advice against extrapolating the model to higher or lower frequencies. The random-effect and residual variances of our model are large, but are still comparable to the recent models by Stafford (2017) and Bora et al (2019).…”

Section: Discussionsupporting

confidence: 74%

“…to Bora et al (2016); (3) calibration of input parameters and methods for finite-fault simulations is more appropriate using GMM-FAs than using GMM-SAs; and (4) inter-frequency correlation of ( ), developed from residuals of a GMM-FA, can facilitate stochastic simulation of realistic ground-motions (Bayless and Abrahamson 2019a;Stafford 2017). In addition, using the random vibration theory (RVT) framework of Bora et al (2016) one can conveniently generate ( ) from a GMM-FA.…”

Section: Introductionmentioning

confidence: 99%

A Regionally Adaptable Ground-Motion Model for Fourier Amplitude Spectra of Shallow Crustal Earthquakes in Europe

Kotha¹,

Bindi²,

Cotton³

2021

Preprint

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Typical ground-motion models predict the response spectral ordinates (GMM-SA), which are the damped responses of a suite of single-degree-of-freedom oscillators. Response spectra represent the response of an idealized structure to input ground-motion, but not the physics of the actual ground-motion. To complement the regionally adaptable GMM-SA of Kotha et al. (2020), we introduce here a model capable of predicting Fourier amplitudes (GMM-FA); developed from the same Engineering Strong Motion (ESM) dataset for pan-Europe. This GMM-FA reveals the very high variability of high frequency ground-motions, which are completely masked in a GMM-SA. By maintaining the development strategies of GMM-FA identical to that of the GMM-SA, we are able to evaluate the physical meaning of the spatial variability of anelastic attenuation and source characteristics. We find that a fully data-driven geospatial index, Activity Index (AIx), correlates well with the spatial variability of these physical effects. AIx is a fuzzy combination of seismicity and crustal parameters, and can be used to adapt the attenuation and source non-ergodicity of the GMM-FA to regions and tectonic localities sparsely sampled in ESM. While AIx, and a few other parameters we touch upon, may help understand the spatial variability of high frequency attenuation and source effects, the high frequency site-response variability - dominating the overall aleatory variance - is yet unresolvable. With the rapid increase in quantity and quality of ground-motion datasets, we call for an upgrade of regionalization techniques, site-characterisation, and a paradigm shift to Fourier ground-motion models to complement the traditional response spectra prediction models.

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“…There are conflicting opinions about the rupture- or region-dependence of IM correlations in the literature. While some studies (Azarbakht et al, 2014; Kotha et al, 2017; Papadopoulos et al, 2019; Stafford, 2017) report dependence of IM correlations on the rupture properties, other studies such as Baker and Bradley (2017) report insignificant dependence. Herein, following the approach described by Baker and Bradley (2017), we analyze the dependence of the correlation coefficients of this study on magnitude ( M ), distance ( R ), and average shear wave velocity in the upper 30 m layer of soil ( Vs 30 ).…”

Section: Magnitude- Distance- and Vs30-dependence Of Correlation Comentioning

confidence: 98%

Correlation of spectral acceleration values of vertical and horizontal ground motion pairs

Kohrangi¹,

Παπαδόπουλος

Bazzurro

et al. 2020

Earthquake Spectra

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We present correlation coefficient estimates between a number of ground motion intensity measures ( IMs), as measured from the NGA-West2 database, with focus on the correlation of vertical–vertical and vertical–horizontal ground motion components. The IMs considered include spectral accelerations with periods from 0.01 to 10 s, peak ground acceleration, peak ground velocity, and significant duration (for 5%–75% and 5%–95% definitions). To facilitate their use, parametric equations are also fitted to the correlation models. Finally, the dependence of the obtained correlation coefficients to magnitude, distance, and Vs30 is evaluated.

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Interfrequency Correlations among Fourier Spectral Ordinates and Implications for Stochastic Ground‐Motion Simulation

Cited by 26 publications

References 41 publications

Correlations of spectral accelerations in the Chilean subduction zone

Correlations of spectral accelerations in the Chilean subduction zone

A Regionally Adaptable Ground-Motion Model for Fourier Amplitude Spectra of Shallow Crustal Earthquakes in Europe

Correlation of spectral acceleration values of vertical and horizontal ground motion pairs

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