Attenuation and velocity structure from diffuse coda waves: Constraints from underground array data

Galluzzo, Danilo; Rocca, Mario La; Margerin, Ludovic; Pezzo, Edoardo Del; Scarpa, Roberto

doi:10.1016/j.pepi.2014.12.004

Cited by 15 publications

(17 citation statements)

References 30 publications

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“…In our study, we would have expected a value near 1.0, as also found in studies where Q and geometrical spreading have been determined simultaneously. Galluzzo et al (2015) found that above 6 Hz, the coda waves were pure body waves, whereas below 6 Hz they were a mixture of surface and body waves. Thus, the geometrical spreading parameter could be less than 1 for lower frequencies.…”

Section: The Geometrical Spreading Parameter βmentioning

confidence: 99%

CodaQin Different Tectonic Areas, Influence of Processing Parameters

Havskov¹,

Sørensen²,

Vales³

et al. 2016

Bulletin of the Seismological Society of America

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Published results of coda Q show a large variation in values. These variations are often claimed to be related to different tectonics, whereas they might just be related to using different assumptions in the processing, leading to different input parameters for the analysis. In this study, the effect of using different processing parameters is investigated and significant differences, particularly at low frequencies, are observed. We find a new set of optimal parameters, which we recommend using in future studies. Using a short lapse time of 30 s and optimal parameters, data from both similar and very different tectonic regions are used to calculate coda Q using the same program and the same parameters.

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Section: The Geometrical Spreading Parameter βmentioning

confidence: 99%

CodaQin Different Tectonic Areas, Influence of Processing Parameters

Havskov¹,

Sørensen²,

Vales³

et al. 2016

Bulletin of the Seismological Society of America

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show abstract

“…[13], where the attenuation and scattering parameters observed at different frequencies are depth dependent, with increasing frequency sampling deeper structure. At shallow depths (<200 m) the low frequency coda is strongly affected by surface waves [30,31] and so at 3 Hz the scattering anomaly is associated with the scattering volcanic edifice but is also strongly affected (as are all measured frequencies) by the presence of high scattering anomalies to the NE and E of the volcano. From 6 Hz to 9 Hz features are associated with the SHZ reducing the amount of observed scattering, suggesting a strongly coherent boundary forming this feature at 2.9 km depth.…”

Section: Diffusionmentioning

confidence: 97%

“…For body waves p = 3 and for surface waves p = 2. As surface waves have been observed to strongly affect the coda at low frequencies (<3 Hz) [30,31], the dominance of body waves is assumed. The diffusion coefficient is related to the physical medium by the transport mean free path l tr and seismic velocity v by:…”

Section: Diffusion Model Theorymentioning

confidence: 99%

Investigating the Apparent Seismic Diffusivity of Near-Receiver Geology at Mount St. Helens Volcano, USA

et al. 2017

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Abstract:We present an expanded approach of the diffusive approximation to map strongly scattering geological structures in volcanic environments using seismic coda intensities and a diffusive approximation. Seismic data from a remarkably consistent hydrothermal source of Long-Period (LP) earthquakes, that was active during the late 2004 portion of the 2004-2008 dome building eruption of Mount St. Helens Volcano, are used to obtain coefficient values for diffusion and attenuation, and describe the rate at which seismic energy radiates into the surrounding medium. The results are then spatially plotted as a function of near-receiver geology to generate maps of near-surface geological and geophysical features. They indicate that the diffusion coefficient is a marker of the near-receiver geology, while the attenuation coefficients are sensitive to deeper volcanic structures. As previously observed by other studies, two main scattering regimes affect the coda envelopes: a diffusive, multiple-scattering regime close to the volcanic edifice and a much weaker, single-to-multiple scattering regime at higher source-receiver offsets. Within the diffusive, multiple-scattering regime, the spatial variations of the diffusion coefficient are sufficiently robust to show the features of laterally-extended, coherent, shallow geological structures.

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“…This interval, in the long period bandwidth (0.1-1 Hz) and high frequency range (1-4 Hz), might be in the order of 1-1.5 h and 3-24 s long, respectively (Gorbatikov and Stepanova, 2008;Wang et al, 2014;Zhong et al, 2015a, b). This characteristic is substantially important.…”

mentioning

confidence: 97%

“…For propagation distances typically less than the mean free path, defined as the distance between two successive scattering anomalies, the coherent part is dominance over the incoherent part, while for times more than the mean free time, waves bounce on several heterogeneities and enter into the 5 multiple scattering regime (Hillers et al, 2012(Hillers et al, , 2013Galluzzo et al, 2015). Thereafter scattering sequences gradually distort the phase and amplitude of the incident plane wave front and also gain stability by temporal stabilization of the S-to-P deformation energy ratio, known as equipartitioning (Hillers et al, 2012).…”

mentioning

confidence: 99%

Constraining on the Stationarity of Signal with Time-Frequency Surrogates to Enhance the Reliability of Singularity Spectrum Attributes of Random Seismic Noise Wavefield

Hamed

Shomali

Moradi

2017

Preprint

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Abstract.Existence of a self-affine long range persistence in the seismic noise time series evidences that the current state of system is not in the pure diffused regime and transition from coherent to incoherent motion is still on progress. Rate of this 15 evolving transition can be indirectly linked to the degree of heterogeneity of medium, thus in this paper we tried to gain an insight into the heterogeneity of the medium by analyzing the width, extreme and asymmetrical trend of multifractal spectrum of seismic records. Nonetheless, toward high frequency ranges a seismic signal itself loses its stationarity short while after its recording onset time. Experimentally, the long-range correlation of a stationary time series (with 0 < ℎ(2) < 1) can be discerned from a non-stationary process (with ℎ(2) > 1) by examining the values of scaling exponent ℎ(2), 20 however, changing in the fractal properties in the crossover time scales in time series don't permit us to ascribe a single amount for ℎ(2) and without executing additional analysis on the stationarity length of signals, direct calculation of such long range correlation and fractal dimensions might be biased. Hence, in this paper we examined the inherent stationarity of a signal relative to the different observation scales in the stochastic contexts before feeding the signal into the cycle of DFA.This method is based on the comparison between global and local features of the original signal and its synthesized time-25 frequency surrogates; therefor it can effectively improve the accuracy of results. Our approach proves the existence of a high-velocity anomalous feature in the right flank of Sahand inactive volcano where it is surrounded by heterogeneous lowvelocity structures and extended to the shallower than ~3 km depth beneath this region at the northwestern of Iran.

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Attenuation and velocity structure from diffuse coda waves: Constraints from underground array data

Cited by 15 publications

References 30 publications

CodaQin Different Tectonic Areas, Influence of Processing Parameters

CodaQin Different Tectonic Areas, Influence of Processing Parameters

Investigating the Apparent Seismic Diffusivity of Near-Receiver Geology at Mount St. Helens Volcano, USA

Constraining on the Stationarity of Signal with Time-Frequency Surrogates to Enhance the Reliability of Singularity Spectrum Attributes of Random Seismic Noise Wavefield

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