The Density Jump at the Inner Core Boundary in the Eastern and Western Hemispheres

Krasnoshchekov, D.; Ovtchinnikov, V. M.

doi:10.1134/s1028334x18020046

Cited by 3 publications

(5 citation statements)

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“…Such hemispherical asymmetry was also suggested by Krasnoshchekov and Ovtchinnikov (), who simply compared binned averages of the above presented PKiKP/PcP amplitude ratios with standard amplitude ratio curves. Their interpretation looks even more solid in view of the above analysis that adds differential travel times and replaces the simple binned averages with their large uncertainties by k ‐order α‐shape yielding robust estimates of distance dependency.…”

Section: Discussionsupporting

confidence: 64%

“…Here we use the new computational geometry tool of k ‐order α‐shape to robustly reconstruct the distance dependence of PKiKP‐PcP differential travel times and amplitudes and analyze the obtained dependencies in terms of their relation to structural heterogeneities of the Earth's crust, mantle, and core. We find that PKiKP‐PcP differential travel times yield more support to IC hemispherical asymmetry suggested in Krasnoshchekov and Ovtchinnikov (), but mosaic surface of the IC cannot be precluded as well.…”

Section: Introductionsupporting

confidence: 65%

“…This bias interpretable in terms of either ICB or CMB density contrasts is illustrated by the relevant α‐shape reconstruction curves plotted in Figure . Previous studies, including Krasnoshchekov and Ovtchinnikov (), analyzed conventional polygon curves built on the base of binned averages. Unlike k ‐order α‐shapes, they feature large uncertainties and provide no information on shape variation of PKiKP/PcP distance dependence that can be discussed and interpreted in terms of structural inhomogeneities of the Earth.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, in the problem of sampling the ICB with PKiKP, where the coverage and number of samples are extremely limited, enhancing the dataset is of chief importance to improve the level of accuracy and confidence in the observations. In this paper we revisit heterogeneities of ICB using the newly presented in Krasnoshchekov and Ovtchinnikov () database of a total of more than 1,300 new differential travel times and amplitude ratios of PKiKP and PcP measured at 3.2–35.2° and reflected off two spots in the western and eastern hemispheres of the Earth's core. Krasnoshchekov and Ovtchinnikov () did not analyze differential travel times but compared binned averages of PKiKP/PcP amplitude ratios with model predictions and indicated that hemispherical asymmetry of the Earth's IC could explain the measurements.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we revisit heterogeneities of ICB using the newly presented in Krasnoshchekov and Ovtchinnikov () database of a total of more than 1,300 new differential travel times and amplitude ratios of PKiKP and PcP measured at 3.2–35.2° and reflected off two spots in the western and eastern hemispheres of the Earth's core. Krasnoshchekov and Ovtchinnikov () did not analyze differential travel times but compared binned averages of PKiKP/PcP amplitude ratios with model predictions and indicated that hemispherical asymmetry of the Earth's IC could explain the measurements. Here we use the new computational geometry tool of k ‐order α‐shape to robustly reconstruct the distance dependence of PKiKP‐PcP differential travel times and amplitudes and analyze the obtained dependencies in terms of their relation to structural heterogeneities of the Earth's crust, mantle, and core.…”

Section: Introductionmentioning

confidence: 99%

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Dissimilarity of the Earth's Inner Core Surface Under South America and Northeastern Asia Revealed by Core Reflected Phases

2019

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Resolving topography of the inner core boundary (ICB) and the structure and composition of the nearby region is key to improving our understanding of solidification of the Earth's inner core. Observations of travel times and amplitudes of short-period seismic phases of PKiKP and PcP reflected, respectively, off the inner and outer boundary of the liquid core, provide essential constraints on the properties of this region. We revisit heterogeneities of ICB using a total of more than 1,300 new differential travel times and amplitude ratios of PKiKP and PcP measured at 3.2-35.2°and reflected off the core's boundaries under Northeastern Asia and South America. We observe a statistically significant systematic bias between the measurements collected in the two spots. We carefully examine its origin in terms of contributions by various Earth's shells and find that most of variance in PKiKP-PcP differential travel times measured above the epicentral distance of 16.5°in Northeastern Asia can be accounted for by mantle corrections. We find slight disparity of about 1-3 km between the outer core thickness under Asia and America; the ICB density jump under Northeastern Asia is about 0.3 g/cm 3 , which is three times as small as under South America. The findings are interpretable either as evidence for inner core hemispherical asymmetry, whereby crystallization dominates in the West and melting in the East (not vice versa), or in terms of two disconnected mosaic patches with contrasting properties.

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Section: Discussionsupporting

confidence: 64%

Section: Introductionsupporting

confidence: 65%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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