Frequency-dependent Attenuation of High-frequency P and S Waves in the Upper Crust in Western Nagano, Japan

Yoshimoto, Keitaro; Sato, Hayato; Iio, Yoshihisa; Ito, H.; Ohminato, Takao; Ohtake, Masakazu

doi:10.1007/s000240050205

Cited by 41 publications

(11 citation statements)

References 16 publications

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“…Winkler and Nur (1982) find that partially water-saturated sedimentary rocks attenuate P waves more strongly than S waves. These observations are also in agreement with many previous studies at seismogenic depths, for example, , Abercrombie (1995), Yoshimoto et al (1998), and Prejean and Ellsworth (2001).…”

Section: Resultssupporting

confidence: 94%

“…Figure 11 shows the relationship between ͗ln[A c d/A c ]͘ and d for the range of frequencies. Although the scatter of the data is large, Yoshimoto et al (1993) and Yoshimoto et al (1998) find similar variations in results; possible explanations include variation with magnitude, miscalculation of geometrical spreading, and the effect of window length used to measure the direct and coda wave amplitudes (Yoshimoto et al, 1993). The relationships obtained from these results are as follows: Figure 12 shows the Q(f ) models with their standard deviations.…”

Section: Radiated Seismic Energy Calculated From Q(f)mentioning

confidence: 78%

“…It is known that Q is roughly proportional to frequency above 1 Hz (e.g., Kvamme and Havskov, 1989;Yoshimoto et al, 1998). However, most previous studies do not use a frequency-dependent Q operator to estimate source parameters, and the validity of assuming frequency-independent attenuation is uncertain.…”

Section: Introductionmentioning

confidence: 98%

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Source Parameter Scaling for Small Earthquakes Observed at the Western Nagano 800-m-Deep Borehole, Central Japan

Stork

Ito

2004

Bulletin of the Seismological Society of America

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Source parameters of 68 small earthquakes (0.6 Ͻ M W Ͻ 3.0) in western Nagano, Japan, are investigated to determine the scaling of static stress drop (Dr s ) and apparent stress (r a ) with seismic moment (M 0 ). Data from the 800-m-deep borehole in the area provides clean recordings containing a wide range of frequencies. Source parameters are determined by manipulation of P and S spectra in the frequency domain using individually determined time window lengths for arrivals on each seismogram. Frequency-independent quality factors, Q, corner frequencies, f c and the amplitude spectra levels are estimated with the best-fitting Brune (1970) x 2 model. A frequency-dependent attenuation model, Q(f ), is calculated by spectra normalization.Static stress drop Dr s is self-similar for 10 10 Ͻ M 0 Ͻ 10 13 N m and values range between 0.01 and 10 MPa. An F distribution test shows there is a 10% probability that r a calculated from Q has a constant mean value for 10 10 Ͻ M 0 Ͻ 10 13 N m. Furthermore, r a calculated using Q(f ) has a significant probability that there is a change in r a values with M 0 . Using Q(f ), 0.02 Ͻ r a Ͻ 2 MPa for M 0 Ͼ 10 11 N m, and 0.002 Ͻ r a Ͻ 0.2 MPa for M 0 Ͻ 10 11 N m, a narrower range than Q analysis results.Limits in recorded frequencies, variations in time window length, and source complexity are not found to significantly affect the calculation of r a . Therefore, the constant scaling of Dr s with M 0 and the nonsimilarity and breakdown in r a scaling could be true characteristics of small earthquakes (M W Ͻ1.3).

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Section: Resultssupporting

confidence: 94%

Section: Radiated Seismic Energy Calculated From Q(f)mentioning

confidence: 78%

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Source Parameter Scaling for Small Earthquakes Observed at the Western Nagano 800-m-Deep Borehole, Central Japan

Stork

Ito

2004

Bulletin of the Seismological Society of America

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“…(1989) Castro et al (1997) (e.g. Yoshimoto et al 1993Yoshimoto et al , 1998 where the intrinsic attenuation is dominant and independent of the scattering attenuation. For instance, the intrinsic attenuation in the Kanto area (see, Yoshimoto et al 1993) is about twice the scattering attenuation and varies independently with frequency from the scattering attenuation variation (Fehler et al 1992).…”

Section: General Patternmentioning

confidence: 99%

“…Hatzidimitriou 1995;Tselentis 1998;Yoshimoto et al 1998;Adams & Abercrombie 1998;Chung & Sato 2001).…”

Section: Introductionmentioning

confidence: 98%

Scattering attenuation ratios ofPandSwaves in elastic media

Hong¹

2004

Geophysical Journal International

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S U M M A R YThe variation of scattering attenuation ratios of P and S waves (Q −1 P /Q −1 S ) is investigated in elastic media by using numerical simulations and theoretical expressions based on the firstorder Born approximation. Numerical results from stochastic random media (von Karman, exponential, Gaussian) with mild velocity perturbation (10 per cent in this study) are represented well by theoretical attenuation curves with a minimum scattering angle of 60-90 • . The level of scattering attenuation ratios is dependent on the velocity ratio (γ = α 0 /β 0 ) and the type of medium. The change of perturbation in the density introduces a relatively small variation in attenuation ratio. Attenuation ratios are proportional to normalized frequency (fa, frequencyby-correlation length) at the intermediate-frequency range (0.1 km s −1 < f a < 10 km s −1 ) and determined constant at the high-frequency ( f a > 10 km s −1 ) and low-frequency ( f a < 1 km s −1 ) regimes. The von Karman-type models look appropriate for the representation of small-scale variation in the Earth. The scattering attenuation ratios can be implemented for the investigation of small-scale heterogeneities in the Earth.

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Source parameter scaling and radiation efficiency of microearthquakes along the Irpinia fault zone in southern Apennines, Italy

2014

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We analyzed the P and S wave displacement spectra of 717 microearthquakes in the moment range 4 × 10 9 À 2 × 10 14 N m recorded at the dense networks operating in southern Apennines (Italy) and deployed along the 1980 M s 6.9 Irpinia earthquake fault zone. Source, attenuation, and site parameters are estimated by using a parametric modeling approach, which is combined with a multistep, nonlinear inversion strategy. We found that in the analyzed frequency band, an attenuation model with constant Q has to be preferred to frequency-dependent Q models. Consistent estimates of the median P and S quality factors e Q P ¼ 167 (90; 296) and e Q S ¼ 226 (114; 417) are obtained from two different techniques and relatively high values of Q S /Q P (median value 1.3, (0.8; 2.1)) are found in the same depth range where high V P /V S and a peak in seismicity distribution are observed. This is the evidence for a highly fractured, partially, or completely fluid-saturated medium embedding the Irpinia fault zone, down to crustal depths of 15-20 km. A nearly constant stress drop ( f Δσ ¼ 1:4 MPa, (0.4; 5.0)) and apparent stress (e τ a ¼ 0:1 MPa, (0.03, 0.4)) scaling of P and S corner frequencies and seismic energies is observed above a seismic moment value of about 10 11 N m. The measured radiation efficiency is low (g η SW ¼ 0:06; 0:03; 0:13 ð Þ ), e.g., the radiated energy is only a small fraction of the whole energy spent by friction and fracture development. A large positive dynamic overshoot (high dynamic shear strength) can be the dominant mechanism controlling the microearthquake fractures along the Irpinia fault zone.

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Frequency-dependent Attenuation of High-frequency P and S Waves in the Upper Crust in Western Nagano, Japan

Cited by 41 publications

References 16 publications

Source Parameter Scaling for Small Earthquakes Observed at the Western Nagano 800-m-Deep Borehole, Central Japan

Source Parameter Scaling for Small Earthquakes Observed at the Western Nagano 800-m-Deep Borehole, Central Japan

Scattering attenuation ratios ofPandSwaves in elastic media

Source parameter scaling and radiation efficiency of microearthquakes along the Irpinia fault zone in southern Apennines, Italy

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