Upper mantle slab under Alaska: contribution to anomalous core-phase observations on south-Sandwich to Alaska paths
International audience Observations of travel time anomalies of inner core-sensitive PKPdf seismic body waves, as a function of path orientation with respect to the earth's rotation axis, have been interpreted as evidence of anisotropy in the inner core. Paths from earthquakes in the South Sand...
Published in: | Physics of the Earth and Planetary Interiors |
---|---|
Main Authors: | , , |
Other Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2020
|
Subjects: | |
Online Access: | https://hal-insu.archives-ouvertes.fr/insu-03584801 https://doi.org/10.1016/j.pepi.2020.106427 |
id |
ftunivnantes:oai:HAL:insu-03584801v1 |
---|---|
record_format |
openpolar |
spelling |
ftunivnantes:oai:HAL:insu-03584801v1 2023-05-15T18:23:34+02:00 Upper mantle slab under Alaska: contribution to anomalous core-phase observations on south-Sandwich to Alaska paths Frost, Daniel A. Romanowicz, Barbara Roecker, Steve Institut de Physique du Globe de Paris (IPGP (UMR_7154)) Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité) 2020 https://hal-insu.archives-ouvertes.fr/insu-03584801 https://doi.org/10.1016/j.pepi.2020.106427 en eng HAL CCSD info:eu-repo/semantics/altIdentifier/doi/10.1016/j.pepi.2020.106427 insu-03584801 https://hal-insu.archives-ouvertes.fr/insu-03584801 BIBCODE: 2020PEPI.29906427F doi:10.1016/j.pepi.2020.106427 Physics of the Earth and Planetary Interiors https://hal-insu.archives-ouvertes.fr/insu-03584801 Physics of the Earth and Planetary Interiors, 2020, 299, 18 pp. ⟨10.1016/j.pepi.2020.106427⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2020 ftunivnantes https://doi.org/10.1016/j.pepi.2020.106427 2022-12-07T00:43:31Z International audience Observations of travel time anomalies of inner core-sensitive PKPdf seismic body waves, as a function of path orientation with respect to the earth's rotation axis, have been interpreted as evidence of anisotropy in the inner core. Paths from earthquakes in the South Sandwich Islands to stations in Alaska show strongly anomalous travel times, with a large spread that is not compatible with simple models of anisotropy. Here we assess the impact of strong velocity heterogeneity under Alaska on the travel times, directions of arrival and amplitudes of PKPdf. We use 3D ray-tracing and 2.5D waveform modelling through a new, high-resolution tomography model of the upper mantle beneath Alaska. We find that the structure beneath Alaska, notably the subducting slab, is reflected in the patterns of these PKPdf observations, and this can be replicated by our model. We also find similar patterns in observed teleseismic P waves that can likewise be explained by our slab model. We conclude that at least 2 s of the travel time anomaly often attributed to inner core anisotropy is due to slab effects in the upper mantle beneath Alaska. Article in Journal/Newspaper South Sandwich Islands Alaska Université de Nantes: HAL-UNIV-NANTES Sandwich Islands South Sandwich Islands Physics of the Earth and Planetary Interiors 299 106427 |
institution |
Open Polar |
collection |
Université de Nantes: HAL-UNIV-NANTES |
op_collection_id |
ftunivnantes |
language |
English |
topic |
[SDU]Sciences of the Universe [physics] |
spellingShingle |
[SDU]Sciences of the Universe [physics] Frost, Daniel A. Romanowicz, Barbara Roecker, Steve Upper mantle slab under Alaska: contribution to anomalous core-phase observations on south-Sandwich to Alaska paths |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
International audience Observations of travel time anomalies of inner core-sensitive PKPdf seismic body waves, as a function of path orientation with respect to the earth's rotation axis, have been interpreted as evidence of anisotropy in the inner core. Paths from earthquakes in the South Sandwich Islands to stations in Alaska show strongly anomalous travel times, with a large spread that is not compatible with simple models of anisotropy. Here we assess the impact of strong velocity heterogeneity under Alaska on the travel times, directions of arrival and amplitudes of PKPdf. We use 3D ray-tracing and 2.5D waveform modelling through a new, high-resolution tomography model of the upper mantle beneath Alaska. We find that the structure beneath Alaska, notably the subducting slab, is reflected in the patterns of these PKPdf observations, and this can be replicated by our model. We also find similar patterns in observed teleseismic P waves that can likewise be explained by our slab model. We conclude that at least 2 s of the travel time anomaly often attributed to inner core anisotropy is due to slab effects in the upper mantle beneath Alaska. |
author2 |
Institut de Physique du Globe de Paris (IPGP (UMR_7154)) Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité) |
format |
Article in Journal/Newspaper |
author |
Frost, Daniel A. Romanowicz, Barbara Roecker, Steve |
author_facet |
Frost, Daniel A. Romanowicz, Barbara Roecker, Steve |
author_sort |
Frost, Daniel A. |
title |
Upper mantle slab under Alaska: contribution to anomalous core-phase observations on south-Sandwich to Alaska paths |
title_short |
Upper mantle slab under Alaska: contribution to anomalous core-phase observations on south-Sandwich to Alaska paths |
title_full |
Upper mantle slab under Alaska: contribution to anomalous core-phase observations on south-Sandwich to Alaska paths |
title_fullStr |
Upper mantle slab under Alaska: contribution to anomalous core-phase observations on south-Sandwich to Alaska paths |
title_full_unstemmed |
Upper mantle slab under Alaska: contribution to anomalous core-phase observations on south-Sandwich to Alaska paths |
title_sort |
upper mantle slab under alaska: contribution to anomalous core-phase observations on south-sandwich to alaska paths |
publisher |
HAL CCSD |
publishDate |
2020 |
url |
https://hal-insu.archives-ouvertes.fr/insu-03584801 https://doi.org/10.1016/j.pepi.2020.106427 |
geographic |
Sandwich Islands South Sandwich Islands |
geographic_facet |
Sandwich Islands South Sandwich Islands |
genre |
South Sandwich Islands Alaska |
genre_facet |
South Sandwich Islands Alaska |
op_source |
Physics of the Earth and Planetary Interiors https://hal-insu.archives-ouvertes.fr/insu-03584801 Physics of the Earth and Planetary Interiors, 2020, 299, 18 pp. ⟨10.1016/j.pepi.2020.106427⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.pepi.2020.106427 insu-03584801 https://hal-insu.archives-ouvertes.fr/insu-03584801 BIBCODE: 2020PEPI.29906427F doi:10.1016/j.pepi.2020.106427 |
op_doi |
https://doi.org/10.1016/j.pepi.2020.106427 |
container_title |
Physics of the Earth and Planetary Interiors |
container_volume |
299 |
container_start_page |
106427 |
_version_ |
1766203587641212928 |