Frequency Dependence of Coda Q, Part I: Numerical Modeling and Examples from Peaceful Nuclear Explosions

Morozov, Igor B.; Zhang, Chaoying; Duenow, Joel N.; Морозова, Е. А.; Smithson, Scott B.

doi:10.1785/0120080037

Cited by 17 publications

(15 citation statements)

References 54 publications

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“…9a) were nearly identical to those independently measured from the data (Fig. 9c; Morozov et al 2006; Morozov et al 2008). The modelling used realistic layered lithospheric structures derived from detailed studies of this PNE line (Morozov et al 1998; Morozova et al 1999).…”

Section: Discussionsupporting

confidence: 86%

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Geometrical attenuation, frequency dependence ofQ, and the absorption band problem

Morozov¹

2008

Geophysical Journal International

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SUMMARY A geometrical attenuation model is proposed as an alternative to the conventional frequency‐dependent attenuation law Q(f) =Q0(f/f0)η. The new model provides a straightforward differentiation between the geometrical and effective attenuation (Qe) which incorporates the intrinsic attenuation and small‐scale scattering. Unlike the (Q0, η) description, the inversion procedure uses only the spectral amplitude data and does not rely on elaborate theoretical models or restrictive assumptions. Data from over 40 reported studies were transformed to the new parametrization. The levels of geometrical attenuation strongly correlate with crustal tectonic types and decrease with tectonic age. The corrected values of Qe are frequency‐independent and generally significantly higher than Q0 and show no significant correlation with tectonic age. Several case studies were revisited in detail, with significant changes in the interpretations. The absorption‐band and the ‘10‐Hz transition’ are not found in the corrected Qe data, and therefore, these phenomena are interpreted as related to geometrical attenuation. The absorption band could correspond to changes in the dominant mode content of the wavefield as the frequency changes from about 0.1 to 100 Hz. Alternatively, it could also be a pure artefact related to the power‐law Q(f) paradigm above. The explicit separation of the geometrical and intrinsic attenuation achieves three goals: (1) it provides an unambiguous, assumption‐ and model‐free description of attenuation, (2) it allows relating the observations to the basic physics and geology and (3) it simplifies the interpretation because of reduced emphasis on the apparent Q(f) dependence. The model also agrees remarkably well with the initial attempts for finite‐difference short‐period coda waveform modelling. Because of its consistency and direct link to the observations, the approach should also help in building robust and transportable coda magnitudes and in seismic regionalization.

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Section: Discussionsupporting

confidence: 86%

“…A more complete and rigorous theoretical treatment with additional examples using surface‐ body‐, and Lg waves are given by Morozov (2008). Coda (γ, Q e ) modelling results in realistic lithospheric structures are reported by Morozov et al (2008).…”

Section: Introductionmentioning

confidence: 99%

Geometrical attenuation, frequency dependence ofQ, and the absorption band problem

Morozov¹

2008

Geophysical Journal International

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“…Observed magnitude for the Kalpakkam and Patna is found to be 6.3 and 7.0, respectively, so this method cannot be applied to these SSA. Maximum magnitude estimation by coda (Q 0 ) (MM4) is given in Tables 5 and 6; Q 0 value for South India is found to be 460 (Mandal and Rastogi 1998;Morozov et al 2008), and it was concluded that South India is under the stable continental region in terms of Q 0 . An estimated coda wave for Himalayan range is M max varies from 4.5 to 7.5 for TFL diverges from 5.14 to 321.03 km M max varies from 4.5 to 7.5 for TFL diverges from 5.14 to 321.03 km NA not available a As per Table 1 varied from 1100 to 1200 (Kumar et al 2007).…”

Section: Maximum Magnitude (M Max ) Estimation By Existing Methodsmentioning

confidence: 98%

Maximum magnitude estimation considering the regional rupture character

et al. 2015

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The main objective of the paper is to develop a new method to estimate the maximum magnitude (M max ) considering the regional rupture character. The proposed method has been explained in detail and examined for both intraplate and active regions. Seismotectonic data has been collected for both the regions, and seismic study area (SSA) map was generated for radii of 150, 300, and 500 km. The regional rupture character was established by considering percentage fault rupture (PFR), which is the ratio of subsurface rupture length (RLD) to total fault length (TFL). PFR is used to arrive RLD and is further used for the estimation of maximum magnitude for each seismic source. Maximum magnitude for both the regions was estimated and compared with the existing methods for determining M max values. The proposed method gives similar M max value irrespective of SSA radius and seismicity. Further seismicity parameters such as magnitude of completeness (M c ), Ba^and Bb^parameters and maximum observed magnitude (M max obs ) were determined for each SSA and used to estimate M max by considering all the existing methods. It is observed from the study that existing deterministic and probabilistic M max estimation methods are sensitive to SSA radius, M c , a and b parameters and M max obs values. However, M max determined from the proposed method is a function of rupture character instead of the seismicity parameters. It was also observed that intraplate region has less PFR when compared to active seismic region.

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“…However, Edwards et al (2008Edwards et al ( , 2011 have shown that a frequency-dependent Q model might give a better spectral fit but can lead to a strong trade-off with the frequency-independent geometrical spreading parameter. Moreover, Morozov et al (2008) obtained a spurious frequency-dependent Q model with α ≈ 0:5 while using a frequency-independent Q for the input numerical simulations. Given that the goal of the present study is to derive an easily adjustable response spectral GMPE, a simple frequency-independent model for Q was considered.…”

Section: Determination Of Stochastic Ground-motionmentioning

confidence: 99%

Development of a Response Spectral Ground‐Motion Prediction Equation (GMPE) for Seismic‐Hazard Analysis from Empirical Fourier Spectral and Duration Models

Bora¹,

Scherbaum²,

Kuehn³

et al. 2015

Bulletin of the Seismological Society of America

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Empirical ground-motion prediction equations (GMPEs) require adjustment to make them appropriate for site-specific scenarios. However, the process of making such adjustments remains a challenge. This article presents a holistic framework for the development of a response spectral GMPE that is easily adjustable to different seismological conditions and does not suffer from the practical problems associated with adjustments in the response spectral domain. The approach for developing a response spectral GMPE is unique, because it combines the predictions of empirical models for the two model components that characterize the spectral and temporal behavior of the ground motion. Essentially, as described in its initial form by Bora et al. (2014), the approach consists of an empirical model for the Fourier amplitude spectrum (FAS) and a model for the ground-motion duration. These two components are combined within the random vibration theory framework to obtain predictions of response spectral ordinates. In addition, FAS corresponding to individual acceleration records are extrapolated beyond the useable frequencies using the stochastic FAS model, obtained by inversion as described in Edwards and Fäh (2013a). To that end, a (oscillator) frequency-dependent duration model, consistent with the empirical FAS model, is also derived. This makes it possible to generate a response spectral model that is easily adjustable to different sets of seismological parameters, such as the stress parameter Δσ, quality factor Q, and kappa κ 0 . The dataset used in Bora et al. (2014), a subset of the RESORCE-2012 database, is considered for the present analysis. Based upon the range of the predictor variables in the selected dataset, the present response spectral GMPE should be considered applicable over the magnitude range of 4 ≤ M w ≤ 7:6 at distances ≤ 200 km.Online Material: GMPE scaling with respect to distance, moment magnitude, V S30 , stress parameter and kappa, ratios for various parameters, and median response.

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Frequency Dependence of Coda Q, Part I: Numerical Modeling and Examples from Peaceful Nuclear Explosions

Cited by 17 publications

References 54 publications

Geometrical attenuation, frequency dependence ofQ, and the absorption band problem

Geometrical attenuation, frequency dependence ofQ, and the absorption band problem

Maximum magnitude estimation considering the regional rupture character

Development of a Response Spectral Ground‐Motion Prediction Equation (GMPE) for Seismic‐Hazard Analysis from Empirical Fourier Spectral and Duration Models

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