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Notes on the variability of reflected inner core phases

Li, Dunzhu and Sun, Daoyuan and Helmberger, Don (2014) Notes on the variability of reflected inner core phases. Earthquake Science, 27 (4). pp. 441-468. ISSN 1674-4519. https://resolver.caltech.edu/CaltechAUTHORS:20170616-103818655

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Abstract

Recent events beneath Central America have produced excellent sets of inner core reflection (PKiKP phase) at high frequency recorded by USArray ranging from 18° to 30°. However, the amplitude of this phase displays considerable scatter with a factor of six or more. Such scatter has been attributed to upper-mantle scattering and the Inner Core Boundary (ICB) in combination. Here, we show that neighboring events share upper-mantle scatterers beneath the receivers, and their ratio allows a clearer image of deep earth structure. After confirming some of the measured variation is indeed due to deep structure, we stacked nearby traces to reduce fine scale variations which are mostly due to shallow structure. Then, the remaining relatively large scale variation pattern of PKiKP phase is caused by the inner core boundary, as demonstrated by numerical experiments. After migration of data to the ICB, we observe a consistent image. We find such a pattern can be explained by a patch of mushy material of a few kilometers high where the material changes gradually from that of the outer core to that of the inner core.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://dx.doi.org/10.1007/s11589-014-0093-9DOIArticle
https://link.springer.com/article/10.1007%2Fs11589-014-0093-9PublisherArticle
http://rdcu.be/tv6lPublisherFree ReadCube access
ORCID:
AuthorORCID
Li, Dunzhu0000-0003-3149-0236
Sun, Daoyuan0000-0003-4461-4664
Additional Information:© 2014 The Seismological Society of China, Institute of Geophysics, China Earthquake Administration and Springer-Verlag Berlin Heidelberg. Received: 28 December 2013; Accepted: 14 April 2014; First Online: 08 August 2014. We thank the Editor and two anonymous reviewers for their comments which greatly improved the manuscript. We also thank Brandon Schmandt for introducing us to these PKiKP data. Data were provided by the IRIS data center and Earthscope USArray. This work was supported by NSF EAR-1053064 and CSEDI EAR-1161046 at CalTech with partial support of D. Sun at USC under EAR-0809023.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-1053064
NSFEAR-1161046
NSFEAR-0809023
Issue or Number:4
Record Number:CaltechAUTHORS:20170616-103818655
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170616-103818655
Official Citation:Li, D., Sun, D. & Helmberger, D. Earthq Sci (2014) 27: 441. doi:10.1007/s11589-014-0093-9
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78274
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Jun 2017 19:13
Last Modified:03 Oct 2019 18:07

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