Constraints on D" beneath the North Atlantic region from P and S traveltimes and amplitudes
International audience In this study, we discuss possible origins of the D reflector beneath the North Atlantic region based on a combined analysis of P and S wave data. We use over 700 USArray station recordings of the M w 6.3 earthquake that occurred in April 2010 in Spain. In order to investigate...
Published in: | Geophysical Journal International |
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Online Access: | https://hal.archives-ouvertes.fr/hal-02944831 https://hal.archives-ouvertes.fr/hal-02944831/document https://hal.archives-ouvertes.fr/hal-02944831/file/DNorthAtlantic.pdf https://doi.org/10.1093/gji/ggy476 |
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ftccsdartic:oai:HAL:hal-02944831v1 2023-05-15T17:30:06+02:00 Constraints on D" beneath the North Atlantic region from P and S traveltimes and amplitudes Durand, Stéphanie Thomas, C Jackson, J Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement Lyon (LGL-TPE) Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL) Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon) Institut für Geophysik Münster Westfälische Wilhelms-Universität Münster (WWU) Berkeley Seismological Laboratory Berkeley University of California Berkeley University of California-University of California 2019 https://hal.archives-ouvertes.fr/hal-02944831 https://hal.archives-ouvertes.fr/hal-02944831/document https://hal.archives-ouvertes.fr/hal-02944831/file/DNorthAtlantic.pdf https://doi.org/10.1093/gji/ggy476 en eng HAL CCSD Oxford University Press (OUP) info:eu-repo/semantics/altIdentifier/doi/10.1093/gji/ggy476 hal-02944831 https://hal.archives-ouvertes.fr/hal-02944831 https://hal.archives-ouvertes.fr/hal-02944831/document https://hal.archives-ouvertes.fr/hal-02944831/file/DNorthAtlantic.pdf doi:10.1093/gji/ggy476 info:eu-repo/semantics/OpenAccess ISSN: 0956-540X EISSN: 1365-246X Geophysical Journal International https://hal.archives-ouvertes.fr/hal-02944831 Geophysical Journal International, Oxford University Press (OUP), 2019, 216, pp.1132 - 1144. ⟨10.1093/gji/ggy476⟩ Probability distributions Atlantic Ocean Structure of the Earth Body waves [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] info:eu-repo/semantics/article Journal articles 2019 ftccsdartic https://doi.org/10.1093/gji/ggy476 2021-11-07T00:44:55Z International audience In this study, we discuss possible origins of the D reflector beneath the North Atlantic region based on a combined analysis of P and S wave data. We use over 700 USArray station recordings of the M w 6.3 earthquake that occurred in April 2010 in Spain. In order to investigate the D layer we look for waves reflected off the top of it, namely PdP and SdS waves, and compare them to the core-mantle boundary (CMB) reflections used as reference phases. The differences in traveltimes and amplitudes are sensitive to D properties. Because the USArray installation generates a dense array, we are able to provide an almost continuous map of the detection or absence of PdP and SdS waves in the North Atlantic region. We use a Bayesian inversion for traveltimes, together with synthetic seismogram calculations, to find the best-fitting D properties, (V p , V s) jumps across the D interface and D thickness. We find that the best-fitting models are for a D layer of about 300 km thick, with or without a velocity gradient of about 30 km at the top of it. Regardless of the model type, positive and similar velocity increases in both P and S velocities at the D interface, ranging from 2.7 to 3.8 per cent, are required to fit the data well. Our data rule out velocity decreases in P and S waves at the D interface as well as no velocity reduction above the CMB. There are also regions where we do not observe PdP and SdS waves. Collectively, these observations suggest lateral variations in both chemistry and temperature, combined with phase transitions. For instance, ancient oceanic basalt debris from the Farallon slab could be modulating the detection of the D reflector in this region. Article in Journal/Newspaper North Atlantic Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Geophysical Journal International 216 2 1132 1144 |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
Probability distributions Atlantic Ocean Structure of the Earth Body waves [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] |
spellingShingle |
Probability distributions Atlantic Ocean Structure of the Earth Body waves [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] Durand, Stéphanie Thomas, C Jackson, J Constraints on D" beneath the North Atlantic region from P and S traveltimes and amplitudes |
topic_facet |
Probability distributions Atlantic Ocean Structure of the Earth Body waves [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] |
description |
International audience In this study, we discuss possible origins of the D reflector beneath the North Atlantic region based on a combined analysis of P and S wave data. We use over 700 USArray station recordings of the M w 6.3 earthquake that occurred in April 2010 in Spain. In order to investigate the D layer we look for waves reflected off the top of it, namely PdP and SdS waves, and compare them to the core-mantle boundary (CMB) reflections used as reference phases. The differences in traveltimes and amplitudes are sensitive to D properties. Because the USArray installation generates a dense array, we are able to provide an almost continuous map of the detection or absence of PdP and SdS waves in the North Atlantic region. We use a Bayesian inversion for traveltimes, together with synthetic seismogram calculations, to find the best-fitting D properties, (V p , V s) jumps across the D interface and D thickness. We find that the best-fitting models are for a D layer of about 300 km thick, with or without a velocity gradient of about 30 km at the top of it. Regardless of the model type, positive and similar velocity increases in both P and S velocities at the D interface, ranging from 2.7 to 3.8 per cent, are required to fit the data well. Our data rule out velocity decreases in P and S waves at the D interface as well as no velocity reduction above the CMB. There are also regions where we do not observe PdP and SdS waves. Collectively, these observations suggest lateral variations in both chemistry and temperature, combined with phase transitions. For instance, ancient oceanic basalt debris from the Farallon slab could be modulating the detection of the D reflector in this region. |
author2 |
Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement Lyon (LGL-TPE) Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL) Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon) Institut für Geophysik Münster Westfälische Wilhelms-Universität Münster (WWU) Berkeley Seismological Laboratory Berkeley University of California Berkeley University of California-University of California |
format |
Article in Journal/Newspaper |
author |
Durand, Stéphanie Thomas, C Jackson, J |
author_facet |
Durand, Stéphanie Thomas, C Jackson, J |
author_sort |
Durand, Stéphanie |
title |
Constraints on D" beneath the North Atlantic region from P and S traveltimes and amplitudes |
title_short |
Constraints on D" beneath the North Atlantic region from P and S traveltimes and amplitudes |
title_full |
Constraints on D" beneath the North Atlantic region from P and S traveltimes and amplitudes |
title_fullStr |
Constraints on D" beneath the North Atlantic region from P and S traveltimes and amplitudes |
title_full_unstemmed |
Constraints on D" beneath the North Atlantic region from P and S traveltimes and amplitudes |
title_sort |
constraints on d" beneath the north atlantic region from p and s traveltimes and amplitudes |
publisher |
HAL CCSD |
publishDate |
2019 |
url |
https://hal.archives-ouvertes.fr/hal-02944831 https://hal.archives-ouvertes.fr/hal-02944831/document https://hal.archives-ouvertes.fr/hal-02944831/file/DNorthAtlantic.pdf https://doi.org/10.1093/gji/ggy476 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
ISSN: 0956-540X EISSN: 1365-246X Geophysical Journal International https://hal.archives-ouvertes.fr/hal-02944831 Geophysical Journal International, Oxford University Press (OUP), 2019, 216, pp.1132 - 1144. ⟨10.1093/gji/ggy476⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1093/gji/ggy476 hal-02944831 https://hal.archives-ouvertes.fr/hal-02944831 https://hal.archives-ouvertes.fr/hal-02944831/document https://hal.archives-ouvertes.fr/hal-02944831/file/DNorthAtlantic.pdf doi:10.1093/gji/ggy476 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.1093/gji/ggy476 |
container_title |
Geophysical Journal International |
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216 |
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2 |
container_start_page |
1132 |
op_container_end_page |
1144 |
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