Intricate heterogeneous structures of the top 300 km of the Earth's inner core inferred from global array data: II. Frequency dependence of inner core attenuation and its implication

Iritani, R.; Takeuchi, Nozomu; Kawakatsu, Hitoshi

doi:10.1016/j.epsl.2014.08.038

Cited by 12 publications

(12 citation statements)

References 43 publications

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“…This type of pattern is in agreement with the studies of Attanayake et al (), Iritani et al (), and Iritani et al (). Our results are specifically in agreement with Figure 4 of Iritani et al (), when one takes into account the depth extent of our data set, which approximately covers the middle third of the depth extent of their models for three regions within the inner core. Our tomograms are therefore providing a perspective on the inner core structure different from the purely hemispherical one.…”

Section: Discussionsupporting

confidence: 93%

“…This leads us back to the models proposed by Aubert et al () and Gubbins et al (), and fast rate of crystallization beneath the Indian Ocean and Southeast Asia and possibly even higher rate of crystallization beneath Central America and western Pacific. Our results agree well with those of Attanayake et al (), Iritani et al (), and Iritani et al () who observed a similar pattern, and the assumption of solidification texturing aligned with the flow in the outer core accounts for the observed seismic anisotropy.…”

Section: Discussion and Interpretationsupporting

confidence: 93%

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Transdimensional Bayesian Attenuation Tomography of the Upper Inner Core

et al. 2019

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Following the linearized attenuation tomography from our previous study (Pejić et al., 2017, https://doi.org/10.1002/2016JB013692), we perform hierarchical transdimensional Bayesian tomography of the upper ≈400 km of the inner core, using 398 globally distributed t∗ estimates. The results are in good agreement with the ones obtained through linearized tomography: they show more complex attenuation pattern than the purely hemispherical one, and the noise estimated from the hierarchical inversion is in good agreement with estimates obtained from the Discrepancy Principle in the previous study. The attenuation pattern we observe gives more weight to the geodynamical models that couple the thermal anomalies of the lowermost mantle to the inner core boundary.

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Section: Discussionsupporting

confidence: 93%

Section: Discussion and Interpretationsupporting

confidence: 93%

Transdimensional Bayesian Attenuation Tomography of the Upper Inner Core

et al. 2019

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“…Nothing about our results suggests the hemispherical dichotomy of the inner core for this layer; however, the results are in line with findings of Attanayake et al [] and Iritani et al [, ]. Note that Attanayake et al [] also used 45° wide bins in their study.…”

Section: Discussionsupporting

confidence: 93%

“…Note that Attanayake et al [] also used 45° wide bins in their study. Our results are specifically in agreement with Figure 4 of Iritani et al [], when one takes into account the depth extent of our data set, which approximately covers the middle third of the depth extent of their models for three regions within the inner core. In all of the results shown, regardless of regularization technique, we observe relatively high attenuation throughout the belt of Pacific‐Atlantic‐Asia.…”

Section: Discussionmentioning

confidence: 99%

“…Their results also showed that the zone of high attenuation extends into the central Pacific region and has reverse (mantle‐like) correlation with velocity. These findings are later confirmed by Iritani et al [, ], who again use waveform inversion based on simulated annealing but with global data this time. They used differential travel times and amplitude ratios between PKIKP and PKPbc or PKPcd (PKiKP) phases covering a distance range from 135° to about 160°.…”

Section: Introductionmentioning

confidence: 99%

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Attenuation tomography of the upper inner core

et al. 2017

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The solidification of the Earth's inner core shapes its texture and rheology, affecting the attenuation and scattering of seismic body waves transmitted through it. Applying attenuation tomography in a Bayesian framework to 398 high‐quality PKIKP waveforms, we invert for the apparent Qp for the uppermost 400 km below the inner core boundary at latitudes 45°S to 45°N. We use damping and smoothing for regularization of the inversion, and it seems that the smoothing regularization combined with the discrepancy principle works better for this particular problem of attenuation tomography. The results are consistent with a regional variation in inner core attenuation more complex than hemispherical, suggesting coupling between inner core solidification and the thermal structure of the lowermost mantle.

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Pn wave geometrical spreading and attenuation in Northeast China and the Korean Peninsula constrained by observations from North Korean nuclear explosions

et al. 2015

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We investigate the geometric spreading and attenuation of seismic Pn waves in Northeast China and the Korean Peninsula. A high‐quality broadband Pn wave data set generated by North Korean nuclear tests is used to constrain the parameters of a frequency‐dependent log‐quadratic geometric spreading function and a power law Pn Q model. The geometric spreading function and apparent Pn wave Q are obtained for Northeast China and the Korean Peninsula between 2.0 and 10.0 Hz. Using the two‐station amplitude ratios of the Pn spectra and correcting them with the known spreading function, we remove the contributions of the source and crust from the apparent Pn Q and retrieve the P wave attenuation information along the pure upper mantle path. We then use both Pn amplitudes and amplitude ratios in a tomographic approach to obtain the upper mantle P wave attenuation in the studied area. The Pn wave spectra observed in China are compared with those recorded in Japan, and the result reveals that the high‐frequency Pn signal across the oceanic path attenuated faster compared with those through the continental path.

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Intricate heterogeneous structures of the top 300 km of the Earth's inner core inferred from global array data: II. Frequency dependence of inner core attenuation and its implication

Cited by 12 publications

References 43 publications

Transdimensional Bayesian Attenuation Tomography of the Upper Inner Core

Transdimensional Bayesian Attenuation Tomography of the Upper Inner Core

Attenuation tomography of the upper inner core

Pn wave geometrical spreading and attenuation in Northeast China and the Korean Peninsula constrained by observations from North Korean nuclear explosions

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