Ambient seismic noise imaging of the lowermost mantle beneath the North Atlantic Ocean

• Published in: Geophysical Journal International
• Main Authors: Retailleau, Lise, Boué, Pierre, Li, Lei, Campillo, Michel
• Other Authors: Observatoire Volcanologique du Piton de la Fournaise (OVPF), Institut de Physique du Globe de Paris (IPG Paris), Department of Geophysics Stanford, Stanford EARTH, Stanford University-Stanford University, Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement IRD : UR219-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), The data set was downloaded and processed using python and the seismological community scientific library obspy (Krischer 2015). The figures were produced using Python and MATLAB and the Python module basemap was used to produce the map. The facilities of IRIS Data ervices, and specifically the IRIS Data Management Center, were used for access to waveforms, related metadata, and/or derived products used in this study. IRIS Data Downloaded from https://academic.oup.com/gji/article-abstract/222/2/1339/5827640 by CNRS user on 23 June 2020Services are funded through the Seismological Facilities for the Advancement of Geoscience (SAGE)Award of theNational Science Foundation under Cooperative Support Agreement EAR-1851048.The computation of the correlation functions presented in this paper was performed performed using the GRICAD infrastructure (https://gricad.univ-grenoble-alpes.f r), which is partly supported by the Equip@Meso project (reference ANR-10-EQPX-29–01) of the programme Investissements d’Avenir supervised by the Agence Nationale pour la Recherche. This work has been supported by a grant from Labex OSUG@2020 (Investissements d’avenir—ANR10 LABX56) and Fondation Simone et Cino Del Duca, Institut de France (Prix scientifique 2013). We acknowledge the support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grantagreement No 742335, F-IMAGE). The research of LR was supported by Pacific Gas and Electric. We thank K. Schaukowitch and the Hume centre for writing and speaking at Stanford for useful comments that helped us to improve the manuscript. We thank the Editor, Michael Ritzwoller, St´ephanie Durand and two anonymousreviewers for their comments and suggestions which helped to improve the quality of this paper
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: Body waves; Seismic noise; Composition and structure of the mantle; Atlantic Ocean; Time-series analysis; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; North Atlantic
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-02879285; https://hal-insu.archives-ouvertes.fr/insu-02879285/document; https://hal-insu.archives-ouvertes.fr/insu-02879285/file/ggaa210.pdf; https://doi.org/10.1093/gji/ggaa210

International audience Body waves can be extracted from correlation functions computed from seismic records even at teleseismic distances. Here we use P and PcP waves from the secondary microseism frequency band that are propagating between Europe and the Eastern United States to image the core-mantle boundary (CMB) and D" structure beneath the North Atlantic. This study presents the first 3-D image of the lower mantle obtained from ocean-generated microseism data. Robustness of our results is evaluated by comparing images produced by propagation in both directions. Our observations reveal complex patterns of lateral and vertical variations of P-wave reflectivity with a particularly strong anomaly extending upward in the lower mantle up to 2600 km deep. We compare these results with synthetic data and associate this anomaly to a Vp velocity increase above the CMB. Our image aims at promoting the study of the lower mantle with microseism noise excitations.