Unified approach to amplitude attenuation and coda excitation in the randomly inhomogeneous lithosphere

Sato, Haruo

doi:10.1007/bf00874359

Cited by 59 publications

(36 citation statements)

References 82 publications

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“…These results are in agreement with Aki (1980) and Sato (1990) that postulated the existence of a lithospheric attenuation peak near 1 Hz. Table 2 lists the Lg Q frequency dependence functions obtained in different regions of the world.…”

Section: Accepted Manuscriptsupporting

confidence: 94%

Frequency-dependent Lg-wave attenuation in northern Morocco

et al. 2015

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Section: Accepted Manuscriptsupporting

confidence: 94%

Frequency-dependent Lg-wave attenuation in northern Morocco

et al. 2015

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“…In the present analysis, we have found the following attenuation characteristics: the power of frequency dependence of Q s ' and Qp' is roughly the same in the high frequency range (>1 Hz); Qp'/QS' ratio is clearly larger than unity at frequencies higher than 1 Hz in contrast to the low frequency range (<1 Hz); Q'-' is smaller than Q-' for all frequency bands. These attentuation characteristics observed, as well as the existence of coda waves, are consistently explained by the single scattering model (Sato 1984(Sato , 1990). In Fig.…”

Section: Physical Mechanism Of Attenuationmentioning

confidence: 53%

Frequency-Dependent Attenuation ofPandSWaves In the Kanto Area, Japan, Based On the Coda-Normalization Method

Yoshimoto

Sato

Ohtake

1993

Geophysical Journal International

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192

176

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S U M M A R YW e propose a new method for the simultaneous measurement of P -and S-wave attentuation by extending the conventional coda-normalization method which had been limited to the estimation of S-wave attenuation. Using this method, we measured frequency-dependent attenuation of both P a n d S waves in the lithosphere beneath the Kanto area, Japan, from seismograms of 174 local earthquakes for the frequency range 1.5 5 f 5 24 Hz. T h e values of Q;' and Q;' corresponding t o peak amplitude decays show strong frequency dependence, a n d are expressed by using power laws Q,' = 0.012f-')73 and Qp' = 0.031f~0Y5, respectively. T h e ratio Qp'/Q.;' is found t o be larger than unity for the whole frequency range. The apparent attenuations of P and S waves with travel distance are almost the same for frequencies higher than 1 Hz. Our results differ from the characteristics of low-frequency wave attenuation reported by other studies for frequencies lower than 1 Hz. This frequency dependence and the ratio may suggest that scattering loss due t o random heterogeneities in the earth medium plays an important role in seismic-wave attenuation in the lithosphere.

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“…QC shows a strong dependence on frequency (Fig. 5) and lapse time Sato's (1984aSato's ( , 1990 model, this shows that the scale length of inhomogeneity is large in low frequency range. It seems natural that QC for low frequency range is responsible to longer wavelength fluctuation of random inhomogeneity.…”

Section: Discussionmentioning

confidence: 99%

Dependence of Coda Q on Frequency and Lapse Time in the Western Nagano Region, Central Japan.

Kosuga

1992

J,Phys,Earth

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We have investigated the dependence of coda Q (QC) on frequency and lapse time using the data observed at short hypocentral distances (1-23 km) over a wide frequency range (1-64 Hz). QC was determined by applying a single isotropic scattering model to the bandpass-filtered seismograms from aftershocks of the 1984 Western Nagano Prefecture, Earthquake. QC depends on frequency, f in Hz, according to a power law, QC=Q0fn. We also found a strong dependence of QC on lapse time, in particular, for short lapse times less than 10 s. This lapse time dependence is characterized by an increase in Q0 and a decrease in n with lapse time. We interpreted this observation as indication of depth variation of QS and estimated a crustal model of one-dimensional QS structure from QC measured at various lapse times. The model exposes low QS in a surface layer and a significant increase in QS with depth in the upper 2 km of the crust. QS in the uppermost crust is compatible with that measured at a deep borehole in the Kanto Plain, central Japan. However, we cannot attribute the lapse time dependence of QC to the sole effect of depth, variation of QS, because QC calculated from the QS model shows more gradual increase than the observation. The scattering coefficient (g0) estimated from the amplitude ratio of S-and coda waves, as well as QS calculated from the energy flux model, suggest a contribution of multiple scattering to the lapse time dependence for long lapse times. For short lapse times, on the other hand, depth variation of g0, as indicated by the change in n with lapse time, is possibly responsible for the sharp increase in QC with lapse time. Thus the apparent lapse time dependence of QC is caused by a combination of depth variation of QS and g0, and multiple scattering effect.

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Unified approach to amplitude attenuation and coda excitation in the randomly inhomogeneous lithosphere

Cited by 59 publications

References 82 publications

Frequency-dependent Lg-wave attenuation in northern Morocco

Frequency-dependent Lg-wave attenuation in northern Morocco

Frequency-Dependent Attenuation ofPandSWaves In the Kanto Area, Japan, Based On the Coda-Normalization Method

Dependence of Coda Q on Frequency and Lapse Time in the Western Nagano Region, Central Japan.

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