New insights into seismic absorption imaging

Sketsiou, Panayiota; Napolitano, Ferdinando; Zenonos, A.; Siena, Luca De

doi:10.1016/j.pepi.2019.106337

Cited by 25 publications

(26 citation statements)

References 56 publications

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“…Sketsiou et al (2020) proposed a new 3‐D coda attenuation tomography method by utilizing the time‐dependent sensitivity kernel. This method is an extension of the above‐mentioned single time‐window approach to multiple time windows.…”

Section: Resultsmentioning

confidence: 99%

“…The choice of sensitivity kernel is important for scattering attenuation tomography. Sketsiou et al (2020) have recently conducted a comprehensive review of the various sensitivity kernels used in coda wave studies. Here we focus on a comparison between our study and recent scattering attenuation tomography studies in terms of the sensitivity kernel.…”

Section: Resultsmentioning

confidence: 99%

“…Although our method is basically similar to that in Akande et al (2019), we are able to overcome the low sensitivity between the source and receivers due to the extensive coverage of our dataset. Sketsiou et al (2020) proposed a new 3-D coda attenuation tomography method by utilizing the time-dependent sensitivity kernel. This method is an extension of the above-mentioned single time-window approach to multiple time windows.…”

Section: 1029/2019jb018742mentioning

confidence: 99%

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3‐D Intrinsic and Scattering Seismic Attenuation Structures Beneath Kyushu, Japan

et al. 2020

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The attenuation of seismic wave energy is caused by intrinsic absorption and scattering. The former involves the conversion of seismic wave energy to heat energy via internal friction due to the anelasticity of the medium, whereas the latter involves the scattering of seismic wave energy due to random elastic heterogeneities in the medium. Quantifying both intrinsic ( Qi−1) and scattering ( Qs−1) attenuation is therefore important for understanding the physical properties of the Earth's interior and predicting seismic wave propagation. Here we develop a new procedure to separately map three‐dimensional (3‐D) Qi−1 and Qs−1 structures. The path‐averaged Qi−1 and Qs−1 values are obtained via an envelope‐fitting approach that employs a multiple‐scattering model. The path‐averaged Qi−1 and Qs−1 structures are then mapped into 3‐D space using a tomographic inversion technique based on sensitivity kernels, which are calculated from a Monte Carlo simulation of the radiative transfer equations. We apply this method to map the crustal structure beneath Kyushu, Japan, and obtain 3‐D Qi−1 and Qs−1 structures for the 1–2, 2–4, and 4–8 Hz frequency bands. The spatial attenuation patterns are similar for each of the analyzed frequency bands, with the spatial variability in Qs−1 being more pronounced than that in Qi−1. The high‐ Qi−1 and Qs−1 regions correspond to the locations of active volcanoes. Conversely, the northern Kyushu area possesses low‐ Qi−1 and Qs−1 zones that correspond to low heat flow and Cretaceous granite, respectively. The overall Qi−1 and Qs−1 distributions correlate with thermal and geological structures, respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: 1029/2019jb018742mentioning

confidence: 99%

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3‐D Intrinsic and Scattering Seismic Attenuation Structures Beneath Kyushu, Japan

et al. 2020

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“…This method has also been applied to volcanic heterogeneities (Nishigami 1997;Calcolé et al 2006;Tramelli et al 2006Tramelli et al , 2009De Siena et al 2014) and has successfully observed heterogeneous anomalies related to fault zones that experience frequent large earthquakes (Nishigami 1991(Nishigami , 2000(Nishigami , 2006Nakata et al 2019). A similar approach using coda envelope tomography has also revealed heterogeneities related to large seismic events Yomogida 2003, 2004;Sketsiou et al 2020).…”

Section: Crustal Heterogeneities Caused By Open Cracks In An Active Fmentioning

confidence: 99%

Seismic Scatter Associated with Earthquakes that Ended a Quiescent Period in Southeastern Korea

Iqbal

Chung

Nam

2020

Preprint

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Two recent hazardous earthquakes ( M 5.8 and 5.5) in southeastern Korea were the largest instrumentally recorded inland events after an abnormally long, seismically quiet, period. In this study, we used coda envelope tomography to observe the heterogeneities related to active faults, which can, in turn, help mitigate seismic hazard in the area. However, this tomography was not able to detect faults in the intraplate region. By separating the periods before and after the M 5.8 earthquake, we analyzed 225 and 204 seismograms obtained from 127 and 86 events, respectively. Both periods showed time-varying heterogeneity correlated with fault activity. Adding 446 seismograms from 235 aftershocks of the two events to the analysis showed us a heterogenous structure that closely correlated to the active faults where the recent earthquakes originated.

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“…The assumption of an initially uniform distribution of heterogeneity is common to most studies that investigated the spatial variability of heterogeneity and attenuation properties with scattered coda waves. Therefore, previous studies are restricted to a first order mapping of deviations from uniform heterogeneity (De Siena et al 2014a,b;Prudencio et al 2015a;Zieger et al 2016;Gabrielli et al 2020;Sketsiou et al 2020) An iterative tomography of this nonlinear problem is therefore impossible so far and requires developments such as those presented here.…”

Section: Sensitivity Kernelsmentioning

confidence: 99%

Sensitivity kernels for static and dynamic tomography of scattering and absorbing media with elastic waves: a probabilistic approach

Zhang

Sens‐Schönfelder

Margerin

2021

Geophysical Journal International

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Summary Scattered seismic coda waves are frequently used to characterize small scale medium heterogeneities, intrinsic attenuation or temporal changes of wave velocity. Spatial variability of these properties raises questions about the spatial sensitivity of seismic coda waves. Especially the continuous monitoring of medium perturbations using ambient seismic noise led to a demand for approaches to image perturbations observed with coda waves. An efficient approach to localize spatial and temporal variations of medium properties is to invert the observations from different source-receiver combinations and different lapse times in the coda for the location of the perturbations. For such an inversion, it is key to calculate the coda-wave sensitivity kernels which describe the connection between observations and the perturbation. Most discussions of sensitivity kernels use the acoustic approximation in a spatially uniform medium and often assume wave propagation in the diffusion regime. We model 2-D multiple non-isotropic scattering in a random elastic medium with spatially variable heterogeneity and attenuation using the radiative transfer equations which we solve with the Monte-Carlo method. Recording of the specific energy density of the wavefield that contains the complete information about the energy density at a given position, time and propagation direction allows us to calculate sensitivity kernels according to rigorous theoretical derivations. The practical calculation of the kernels involves the solution of the adjoint radiative transport equations. We investigate sensitivity kernels that describe the relationships between changes of the model in P- and S-wave velocity, P- and S-wave attenuation, and the strength of fluctuation on the one hand and seismogram envelope, travel time changes and waveform decorrelation as observables on the other hand. These sensitivity kernels reflect the effect of the spatial variations of medium properties on the wavefield and constitute the first step in the development of a tomographic inversion approach for the distribution of small-scale heterogeneity based on scattered waves.

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New insights into seismic absorption imaging

Cited by 25 publications

References 56 publications

3‐D Intrinsic and Scattering Seismic Attenuation Structures Beneath Kyushu, Japan

3‐D Intrinsic and Scattering Seismic Attenuation Structures Beneath Kyushu, Japan

Seismic Scatter Associated with Earthquakes that Ended a Quiescent Period in Southeastern Korea

Sensitivity kernels for static and dynamic tomography of scattering and absorbing media with elastic waves: a probabilistic approach

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