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Analyse Du Bruit Microsismique Associé À La Houle Dans L'océan Indien

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Analyse Du Bruit Microsismique Associé À La Houle Dans L'océan Indien Analyse du bruit microsismique associ´e`ala houle dans l'oc´eanIndien C´elineDavy To cite this version: C´eline Davy. Analyse du bruit microsismique associ´e `a la houle dans l'oc´ean Indien. G´eophysique [physics.geo-ph]. Universit´ede La R´eunion,2015. Fran¸cais. <tel-01391911> HAL Id: tel-01391911 http://hal.univ-reunion.fr/tel-01391911 Submitted on 4 Nov 2016 HAL is a multi-disciplinary open access L'archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destin´eeau d´ep^otet `ala diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publi´esou non, lished or not. The documents may come from ´emanant des ´etablissements d'enseignement et de teaching and research institutions in France or recherche fran¸caisou ´etrangers,des laboratoires abroad, or from public or private research centers. publics ou priv´es. Université de La Réunion – Laboratoire Géosciences Réunion – Institut de Physique du Globe de Paris Ecole Doctorale Sciences Technologies Santé THÈSE Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ DE LA REUNION Spécialité : Sciences de la Terre Par Céline DAVY Analyse du bruit microsismique associé à la houle dans l’océan Indien Soutenue publiquement le 26 novembre 2015, devant le jury composé de : Fabrice ARDHUIN Directeur de Recherches CNRS, IFREMER Rapporteur Karin SIGLOCH Associate Professor, Université d’Oxford Rapporteur Éric BEUCLER Maître de Conférences, Université de Nantes Examinateur Éléonore STUTZMANN Professeur, IPGP Examinateur Guilhem BARRUOL Directeur de Recherches CNRS, Université de La Réunion Directeur Fabrice R. FONTAINE Maître de Conférences, Université de La Réunion Co-Directeur Avant-propos Débutée en mars 2012, cette thèse a été réalisée au laboratoire Géosciences de l’Université de La Réunion, sous la direction de Guilhem Barruol et Fabrice R. Fontaine. Le financement de cette thèse a été assuré par l’École Doctorale STS de l’Université de La Réunion. Les données sismologiques utilisées dans le cadre de ce travail ont été acquises dans le cadre des programmes suivants : RHUM-RUM [Barruol and Sigloch, 2013], cofinancé par l’Agence National de la Recherche (projet ANR-11-BS56-0013) et par le DFG (Deutsche Forschungsgemeinschaft), avec le soutien du CNRS-INSU, des TAAF, de l’iPEV et de l’AWI. GEOSISM-Éparses, cofinancé par le CNRS-INSU, CNRS-INEE, les TAAF et par le projet RHUM-RUM, avec le soutien de l’OSU Réunion. HOULE REUNION, financé par la Région Réunion, l'OSU-Réunion, le programme INSU-SYSTER. Remerciements Je tiens tout d’abord à remercier Guilhem Barruol sans qui l’aboutissement de cette thèse n’aurait pas été possible, pour son encadrement sans faille, ses conseils avisés, son efficacité et pour toute l’aide qu’il m’a apportée dans l’apprentissage du travail de chercheur. Mes remerciements vont également à Fabrice Fontaine pour avoir assuré la co-direction de cette thèse et pour son accompagnement dans la prise en main des outils du sismologue. Je remercie vivement Fabrice Ardhuin et Karin Sigloch d’avoir accepté d’évaluer ce travail en tant que rapporteurs, ainsi qu’Éric Beucler et Éléonore Stutzmann en tant qu’examinateurs. Je tiens également à remercier Éléonore Stutzmann pour sa collaboration, ses conseils pertinents et sa disponibilité lors de mes passages à l’IPGP. D’une façon générale, la préparation de ce travail de recherche m’a amenée à rencontrer un grand nombre de scientifiques de tout horizon, avec lesquels les échanges ont toujours été très enrichissants. Je tiens à les en remercier ici. Un grand merci à Emmanuel Cordier pour son aide précieuse dans tout ce qui concerne l’aspect modélisation de la houle et pour ses nombreux conseils dans l’utilisation du logiciel Matlab, toujours donnés dans la bonne humeur ! Je remercie toute l’équipe RESIF de Grenoble pour leur aide technique dans le traitement et la mise à disposition des données sismologiques acquises dans le cadre de cette thèse. Je remercie chaleureusement toute l’équipe du laboratoire Géosciences de l’Université de La Réunion pour leur accueil et pour l’aide qu’ils m’ont apportée durant ces trois années. Enfin, d’un point de vue plus personnel, je remercie toutes les personnes qui ont contribué à rendre cette expérience professionnelle si enrichissante, tant sur le plan des rencontres et des découvertes que pour les bons moments passés ensemble. Une spéciale dédicace à ma famille créole d’adoption : Sylvie, Bruno et toute leur tribu, ainsi qu’à Jean-Luc des Petits débrouillards et à l’équipe « Paré pas Paré » de la Croix Rouge pour avoir rendu ce séjour à La Réunion inoubliable : mi aime zot tout ! Je remercie naturellement mes parents, à qui je dois d’être arrivée jusqu’ici, et ma Nénène d’amour, pour leur soutien incommensurable et pour tout ce qu’ils représentent pour moi. Je vous aime fort. Big up à l’homme de ma vie [Charles, 2015] qui a rendu tout cela possible … TABLE DES MATIERES Table des matières PARTIE 1 : INTRODUCTION GÉNÉRALE ...................................................................... 1 1.1 Contexte et problématique générale ..................................................................................................... 2 1.2 Étude bibliographique du bruit microsismique ............................................................................... 6 1.2.1. Origine et nature du bruit (de la découverte à la théorie : 1870-1950) ............................ 6 1.2.2. Les microséismes secondaires ............................................................................................................... 9 1.2.3. Les microséismes primaires ..................................................................................................................13 1.2.4. Observations du bruit microsismique (de 1950 à nos jours) ................................................14 1.2.5. Modélisation : de la houle au bruit microsismique .....................................................................16 1.2.6. Utilisations du bruit microsismique..................................................................................................18 PARTIE 2 : LES SOURCES DE MICROSÉISMES SECONDAIRES À L’ÉCHELLE DE L’OCÉAN INDIEN, Relations avec les tempêtes océaniques ............................................................. 19 2.1 Détection lointaine des sources de microséismes secondaires ............................................... 20 2.1.1. Introduction .................................................................................................................................................20 2.1.2. Localisation des sources de microséismes secondaires : méthodes utilisées .................21 2.1.3. Localisation des sources de microséismes secondaires à l’échelle de l’océan Indien par l’analyse de la polarisation .....................................................................................................................................23 2.1.4. Localisation des sources de microséismes secondaires par analyses spectrales .........43 2.2 Détection in situ des sources de microséismes secondaires : le cas des cyclones ........... 63 2.2.1. Les cyclones comme sources de microséismes secondaires ...................................................63 2.2.2. Le suivi spatio-temporel du passage d’un cyclone tropical depuis les observations fond de mer .............................................................................................................................................................................69 2.3 Le suivi des variations climatiques sur le long terme .................................................................. 88 PARTIE 3 : LES SOURCES DE MICROSÉISMES PRIMAIRES DANS L’OCÉAN INDIEN, Impact direct de la houle sur la côte ................................................................................ 90 3.1 Étude bibliographique sur les sources de microséismes primaires ...................................... 91 3.2 Méthodes d'études des sources de microséismes primaires .................................................... 95 3.3 Utilisation d’une station sismique comme houlographe : application aux îles Éparses et à Mayotte ............................................................................................................................................................................ 98 3.3.1. Présentation des îles Éparses ...............................................................................................................98 3.3.2. Installation des stations sismiques dans les îles Éparses et à Mayotte ......................... 106 TABLE DES MATIERES 3.3.3. Suivi des houles australes et cycloniques dans les îles Éparses à partir du bruit microsismique .................................................................................................................................................................... 111 3.3.4. Fonctions de transfert dans les îles Éparses .............................................................................. 136 PARTIE 4 : ANALYSE DE HOULES EXTRÊMES SUR L’ÎLE DE LA RÉUNION .................. 158 4.1 Introduction................................................................................................................................................ 159 4.1.1 Contexte climatique : les houles à La Réunion ............................................................................ 159 4.2 Présentation des observations ..........................................................................................................
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