Anelastic degradation of acoustic pulses in rock

Gladwin, M. T.; Stacey, Frank D.

doi:10.1016/0031-9201(74)90041-7

Cited by 190 publications

(99 citation statements)

References 10 publications

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“…The method for Q estimation presented here is based on the time domain formulation which derives from the classic rise time (or pulse broadening) method [Ricker, 1953;Gladwin and Stacey, 1974;Kjartansson, 1979]. The rise time method assumes that direct (P or S) pulse duration x, generated by a point-like impulsive source, increases with the distance traveled by the wave according to the equation where % is the rise time at the source, T is the travel time of the wave, and Q the quality factor of the medium.…”

Section: Pulse Width (Or Rise Time) Methodsmentioning

confidence: 99%

Source parameters and three‐dimensional attenuation structure from the inversion of microearthquake pulse width data: Method and synthetic tests

Zollo¹,

Lorenzo²

2001

J. Geophys. Res.

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Abstract. We propose a new method to determine source parameters and attenuation structure of a three-dimensional medium based on first P rise time and total pulse width measurements from microearthquake data. The effects of fault finiteness on seismic radiation are taken into account by assuming the rupture model for a circular crack of Sato and Hirasawa (1973). Ray theory synthetic seismograms in a constant Q anelastic medium are computed to derive a set of nonlinear equations which relate the source and attenuation parameters (fault radius, orientation of the fault plane, and quality factor) to the pulse width data (half and total duration of the P waveforms).The numerically built relationships are used to compute the direct problem in the framework of a nonlinear inversion scheme, based on the modified downhill Simplex method. The validity and robustness of the inversion method are tested by synthetic simulations by assuming the sources and receivers configuration of the seismic passive experiment conducted in the Campi Flegrei caldera (southern Italy) during the last microearthquake crisis (1982)(1983)(1984). Different heterogeneous Q models have been considered in order to assess the uncertainty and resolution of source and attenuation parameters for the given acquisition layout. The results of this simulation study indicate that first pulse width data from a local network permit retrieval with sufficient accuracy of the heterogeneous Q structure and fault radii. A rather dense azimuthal coverage of the sources is instead needed to recover the angles (in particular, the fault strike) which define the fault orientation.

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Section: Pulse Width (Or Rise Time) Methodsmentioning

confidence: 99%

Source parameters and three‐dimensional attenuation structure from the inversion of microearthquake pulse width data: Method and synthetic tests

Zollo¹,

Lorenzo²

2001

J. Geophys. Res.

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“…The seismic quality factor (Q), the inverse of seismic attenuation, can be estimated from the seismic data set using different methods, which include the amplitude decay method (Badri and Mooney, 1987), the rise time method (Gladwin and Stacey, 1974), the centroid frequency shift method (Quan and Harris, 1997), wavelet modeling (Jannsen et al, 1985), the pulse broadening method (Hatherly, 1986), the spectral ratio (SR) method (Båth, 1982;Jannsen et al, 1985), and the inversion method (Amundsen and Mittet, 1994). Tonn (1991) compares 10 methods of attenuation estimation using VSP seismograms and concludes that no single method is suitable for all situations.…”

Section: Introductionmentioning

confidence: 99%

Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

et al. 2016

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We have estimated the seismic attenuation in gas hydrate and free-gas-bearing sediments from high-resolution P-cable 3D seismic data from the Vestnesa Ridge on the Arctic continental margin of Svalbard. P-cable data have a broad bandwidth (20-300 Hz), which is extremely advantageous in estimating seismic attenuation in a medium. The seismic quality factor (Q), the inverse of seismic attenuation, is estimated from the seismic data set using the centroid frequency shift and spectral ratio (SR) methods. The centroid frequency shift method establishes a relationship between the change in the centroid frequency of an amplitude spectrum and the Q value of a medium. The SR method estimates the Q value of a medium by studying the differential decay of different frequencies. The broad bandwidth and short offset characteristics of the P-cable data set are useful to continuously map the Q for different layers throughout the 3D seismic volume. The centroid frequency shift method is found to be relatively more stable than the SR method. Q values estimated using these two methods are in concordance with each other. The Q data document attenuation anomalies in the layers in the gas hydrate stability zone above the bottom-simulating reflection (BSR) and in the free gas zone below. Changes in the attenuation anomalies correlate with small-scale fault systems in the Vestnesa Ridge suggesting a strong structural control on the distribution of free gas and gas hydrates in the region. We argued that high and spatially limited Q anomalies in the layer above the BSR indicate the presence of gas hydrates in marine sediments in this setting. Hence, our workflow to analyze Q using high-resolution P-cable 3D seismic data with a large bandwidth could be a potential technique to detect and directly map the distribution of gas hydrates in marine sediments.

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“…The experimental study of GLADWIN and STACEY (1974) showed that the pulse width from an impulsive source is expressed by t/Q, where t is the travel time and Q is the quality factor describing the wave attenuation. From this relation, the pulse width of 0.11 s at the hypocentral distance of 95 km (t _?…”

Section: Analysis and Resultsmentioning

confidence: 99%

Fault length of small-sized earthquakes as estimated from the pulse width of initial P wave.

Ohtake

1986

J,Phys,Earth

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Anelastic degradation of acoustic pulses in rock

Cited by 190 publications

References 10 publications

Source parameters and three‐dimensional attenuation structure from the inversion of microearthquake pulse width data: Method and synthetic tests

Source parameters and three‐dimensional attenuation structure from the inversion of microearthquake pulse width data: Method and synthetic tests

Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

Fault length of small-sized earthquakes as estimated from the pulse width of initial P wave.

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