Non quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core

Abstract We assembled a database consisting of 5,404 PKIKP/PKiKP observations from 555 events, where PKIKP is the phase sampling the inner core (IC) and PKiKP is the phase reflected at the inner core boundary (ICB). Around 138° distances, their differential arrival times and amplitude ratio are most...

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Autores principales:	Marian Ivan, Rongjiang Wang, Rami Hofstetter
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2018
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/8c720604b61d49afb7dcbd4347c01620
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spelling	oai:doaj.org-article:8c720604b61d49afb7dcbd4347c016202021-12-02T15:08:29ZNon quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core10.1038/s41598-018-20657-x2045-2322https://doaj.org/article/8c720604b61d49afb7dcbd4347c016202018-02-01T00:00:00Zhttps://doi.org/10.1038/s41598-018-20657-xhttps://doaj.org/toc/2045-2322Abstract We assembled a database consisting of 5,404 PKIKP/PKiKP observations from 555 events, where PKIKP is the phase sampling the inner core (IC) and PKiKP is the phase reflected at the inner core boundary (ICB). Around 138° distances, their differential arrival times and amplitude ratio are mostly sensitive to the seismic velocity and attenuation structure in the uppermost IC (UIC), respectively. Our observations do not support a large-scale anisotropy in the UIC, but do not exclude its presence in some restricted areas. A robust inversion for the isotropic P-wave velocity perturbations shows a higher velocity cap with a radius of ~60°, approximately centered beneath the Northern Sumatra, with a local low velocity zone beneath the central Indian Ocean. The rest of the UIC, including the Northern part of Eurasia and of the Atlantic Ocean, exhibits mostly lower velocity. Amplitude ratio values of PKIKIP/PKiKP (observed vs. computed) from 548 high signal-to-noise (>5) recordings show a large variance, suggesting only a faint correlation between higher velocity and lower attenuation in the UIC. Our results provide better constraints to the models invoking a heat transfer in the UIC, with a complex temperature pattern near ICB.Marian IvanRongjiang WangRami HofstetterNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 8, Iss 1, Pp 1-8 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Marian Ivan Rongjiang Wang Rami Hofstetter Non quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core
description	Abstract We assembled a database consisting of 5,404 PKIKP/PKiKP observations from 555 events, where PKIKP is the phase sampling the inner core (IC) and PKiKP is the phase reflected at the inner core boundary (ICB). Around 138° distances, their differential arrival times and amplitude ratio are mostly sensitive to the seismic velocity and attenuation structure in the uppermost IC (UIC), respectively. Our observations do not support a large-scale anisotropy in the UIC, but do not exclude its presence in some restricted areas. A robust inversion for the isotropic P-wave velocity perturbations shows a higher velocity cap with a radius of ~60°, approximately centered beneath the Northern Sumatra, with a local low velocity zone beneath the central Indian Ocean. The rest of the UIC, including the Northern part of Eurasia and of the Atlantic Ocean, exhibits mostly lower velocity. Amplitude ratio values of PKIKIP/PKiKP (observed vs. computed) from 548 high signal-to-noise (>5) recordings show a large variance, suggesting only a faint correlation between higher velocity and lower attenuation in the UIC. Our results provide better constraints to the models invoking a heat transfer in the UIC, with a complex temperature pattern near ICB.
format	article
author	Marian Ivan Rongjiang Wang Rami Hofstetter
author_facet	Marian Ivan Rongjiang Wang Rami Hofstetter
author_sort	Marian Ivan
title	Non quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core
title_short	Non quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core
title_full	Non quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core
title_fullStr	Non quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core
title_full_unstemmed	Non quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core
title_sort	non quasi-hemispherical seismological pattern of the earth’s uppermost inner core
publisher	Nature Portfolio
publishDate	2018
url	https://doaj.org/article/8c720604b61d49afb7dcbd4347c01620
work_keys_str_mv	AT marianivan nonquasihemisphericalseismologicalpatternoftheearthsuppermostinnercore AT rongjiangwang nonquasihemisphericalseismologicalpatternoftheearthsuppermostinnercore AT ramihofstetter nonquasihemisphericalseismologicalpatternoftheearthsuppermostinnercore
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Non quasi-Hemispherical Seismological Pattern of the Earth’s Uppermost Inner Core

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