{"id":564,"date":"2015-03-28T11:55:34","date_gmt":"2015-03-28T11:55:34","guid":{"rendered":"https:\/\/blogs.futura-sciences.com\/bardintzeff\/?p=564"},"modified":"2015-03-28T11:58:02","modified_gmt":"2015-03-28T11:58:02","slug":"volcans-dafrique","status":"publish","type":"post","link":"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/","title":{"rendered":"Volcans d\u2019Afrique"},"content":{"rendered":"

Jeudi 26 mars dernier, j\u2019\u00e9tais invit\u00e9 par le Centre Universitaire du Temps Libre (CUTL) de Maintenon (28130), \u00e0 donner une conf\u00e9rence \u00e0 la Salle des f\u00eates de Saint-Piat, sur le th\u00e8me des Volcans d\u2019Afrique.<\/p>\n

Les volcans d\u2019Afrique sont nombreux et vari\u00e9s\u00a0: sur le continent ou dans les \u00eeles tout autour, coul\u00e9es, fontaines, lacs de lave ou panaches de cendres\u2026<\/p>\n

La \u00ab\u00a0corne de l\u2019Afrique\u00a0\u00bb<\/strong><\/p>\n

Au niveau du \u00ab\u00a0Triangle des Afars\u00a0\u00bb, entre l\u2019\u00c9thiopie et la R\u00e9publique de Djibouti, trois structures g\u00e9ologiques majeures se rejoignent :<\/p>\n

– la zone transformante du Jourdain, avec le lac de Tib\u00e9riade, la mer Morte (dont le niveau se situe largement en-dessous de z\u00e9ro\u00a0: – 422 m), jusqu\u2019au golfe d’Aqaba et le golfe de Suez (W), se prolonge par la mer Rouge\u00a0;<\/p>\n

– la dorsale oc\u00e9anique de Carlsberg de l’oc\u00e9an Indien, p\u00e9n\u00e8tre dans golfe d’Aden jusque dans la r\u00e9gion de Tadjoura ;<\/p>\n

– le foss\u00e9 du Rift est africain et ses grands lacs d’effondrement\u00a0: lac Albert, lac \u00c9douard\u2026 Le lac Tanganyika (altitude 775 m), de 677 km long, a une profondeur maximale de 1433\u00a0m\u00a0; son fond se situe donc sous le niveau de la\u00a0mer\u00a0! Le lac Malawi (anciennement Nyassa) mesure 580 km de long, pour une profondeur maximale de 706\u00a0m.<\/p>\n

En \u00c9thiopie, nous retrouvons le lac de lave permanent du volcan Erta Ale, l\u2019un des rares au monde. En 2004, il s\u2019\u00e9tait recouvert d\u2019une pellicule de roche durcie et nous avons pu y descendre, avec Nicolas Hulot et l\u2019\u00e9quipe de Ushua\u00efa-Nature pour des pr\u00e9l\u00e8vements de la lave sous-jacente.<\/p>\n

Non loin, se situe l\u2019\u00e9trange site hydrothermale de Dallol, avec ses eaux acides multicolores. Comme le pr\u00e9cisait Nicolas\u00a0: \u00ab\u00a0On se croirait sur la plan\u00e8te Mars\u00a0!\u00a0\u00bb.<\/p>\n

Un autre lac de lave occupe le crat\u00e8re du Nyiragongo, en R\u00e9publique d\u00e9mocratique du Congo.<\/p>\n

\"Bardintzeff.DJ.10.13.signe\"<\/a><\/p>\n

Le lac de lave de l\u2019Erta Ale en janvier 2003 (\u00a9 J.M. Bardintzeff).<\/p>\n

<\/p>\n

En Tanzanie, culmine l\u2019immense Kilimandjaro (5 895m), coiff\u00e9 par ses neiges \u00e9ternelles et lou\u00e9 par les po\u00e8tes, d\u2019Ernest Hemingway \u00e0 Pascal Danel\u00a0!<\/p>\n

Mais le volcan Ol Doinyo Lengai (2\u00a0886 m) est incontestablement unique au monde puisqu\u2019il lib\u00e8re des carbonatites, laves tr\u00e8s fluides, d\u2019un noir d\u2019encre.<\/p>\n

Madagascar et R\u00e9union<\/strong><\/p>\n

\u00c0 Madagascar, l\u2019\u00eele rouge, entre baobabs, l\u00e9muriens et cam\u00e9l\u00e9ons, se dressent des c\u00f4nes volcaniques assez r\u00e9cents, rappelant certains volcans d\u2019Auvergne. Le lac de crat\u00e8re Tritriva contient des eaux sombres et myst\u00e9rieuses. Pr\u00e8s de Andranomandriatra, se c\u00f4toient des sources thermales, intermittentes et p\u00e9trifiantes.<\/p>\n

L\u2019\u00eele de la R\u00e9union est constitu\u00e9e de deux volcans\u00a0: le piton des Neiges (3 069 m) inactif et \u00e9rod\u00e9 en trois cirques majestueux (Mafate, Cilaos, Salazie) et le piton de la Fournaise (2\u00a0632 m) actif quasi annuellement, sa derni\u00e8re \u00e9ruption remontant au 4-15 f\u00e9vrier 2015.<\/p>\n

Dans l\u2019\u00eele Maurice (anciennement \u00eele de France) voisine, les volcans sont \u00e9teints\u00a0comme le Trou aux cerfs.<\/p>\n

L\u2019Afrique septentrionale et occidentale<\/strong><\/p>\n

D\u2019autres volcans se retrouvent en Afrique du Nord, de l\u2019Alg\u00e9rie \u00e0 la Libye (le Waw an Namous).<\/p>\n

Une ligne volcanique traverse le Cameroun de part en part, des \u00eeles du golfe de Guin\u00e9e jusqu\u2019au lac Tchad, sur pr\u00e8s de 2\u00a0000 km. Le dangereux lac Nyos a lib\u00e9r\u00e9 du gaz carbonique en ao\u00fbt 1986, asphyxiant 1 746 personnes. Les deux derni\u00e8res \u00e9ruptions du mont Cameroun (4\u00a0040 m) remontent \u00e0 1999 et 2000.<\/p>\n

Des \u00eeles volcaniques se situent au large de l\u2019Afrique, dans l\u2019oc\u00e9an Atlantique\u00a0: Le Fogo au Cap-Vert, s\u2019est r\u00e9veill\u00e9 du 23 novembre 2014 au 8 f\u00e9vrier 2015, alors que sa derni\u00e8re \u00e9ruption remontait \u00e0 1995. Les coul\u00e9es de lave ont recouvert les deux villages de Portella et Bangaeira, laissant 1 400 personnes sans abris. Puis l\u2019\u00e9ruption est devenue plus explosive.<\/p>\n

Le voyage peut se poursuivre vers les Canaries et Mad\u00e8re, en direction de l\u2019Europe.<\/p>\n

\"Bardintzeff.SAM_1041.signe\"<\/a><\/p>\n

Le Fogo, dans l\u2019archipel du Cap-Vert, \u00e9met un imposant panache de cendres en janvier 2015\u00a0(\u00a9 J.M. Bardintzeff).<\/p>\n","protected":false},"excerpt":{"rendered":"

Jeudi 26 mars dernier, j\u2019\u00e9tais invit\u00e9 par le Centre Universitaire du Temps Libre (CUTL) de Maintenon (28130), \u00e0 donner une conf\u00e9rence \u00e0 la Salle des f\u00eates de Saint-Piat, sur le th\u00e8me des Volcans d\u2019Afrique. Les volcans d\u2019Afrique sont nombreux et vari\u00e9s\u00a0: sur le continent ou dans les \u00eeles tout autour, coul\u00e9es, fontaines, lacs de lave … Continuer la lecture de Volcans d\u2019Afrique<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_links_to":"","_links_to_target":""},"categories":[1],"tags":[146,85,115,78,147,17,27,114,148,152,150,149,76,125,54,77,3,151],"class_list":["post-564","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-afrique","tag-cameroun","tag-cap-vert","tag-carbonatite","tag-erta-ale","tag-eruption","tag-ethiopie","tag-fogo","tag-kilimandjaro","tag-lac-nyos","tag-libye","tag-madagascar","tag-ol-doinyo-lengai","tag-piton-de-la-fournaise","tag-reunion","tag-tanzanie","tag-volcan","tag-waw-an-namous"],"yoast_head":"\nVolcans d\u2019Afrique, par Jacques-Marie Bardintzeff<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Volcans d\u2019Afrique, par Jacques-Marie Bardintzeff\" \/>\n<meta property=\"og:description\" content=\"Jeudi 26 mars dernier, j\u2019\u00e9tais invit\u00e9 par le Centre Universitaire du Temps Libre (CUTL) de Maintenon (28130), \u00e0 donner une conf\u00e9rence \u00e0 la Salle des f\u00eates de Saint-Piat, sur le th\u00e8me des Volcans d\u2019Afrique. Les volcans d\u2019Afrique sont nombreux et vari\u00e9s\u00a0: sur le continent ou dans les \u00eeles tout autour, coul\u00e9es, fontaines, lacs de lave … Continuer la lecture de Volcans d\u2019Afrique →\" \/>\n<meta property=\"og:url\" content=\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/\" \/>\n<meta property=\"og:site_name\" content=\"VOLCANMANIA : le blog de Jacques-Marie BARDINTZEFF, volcanologue\" \/>\n<meta property=\"article:published_time\" content=\"2015-03-28T11:55:34+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2015-03-28T11:58:02+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/wp-content\/uploads\/sites\/3\/2015\/03\/Bardintzeff.DJ_.10.13.signe_.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1772\" \/>\n\t<meta property=\"og:image:height\" content=\"1132\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"jmbardintzeff\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u00c9crit par\" \/>\n\t<meta name=\"twitter:data1\" content=\"jmbardintzeff\" \/>\n\t<meta name=\"twitter:label2\" content=\"Dur\u00e9e de lecture estim\u00e9e\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/\",\"url\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/\",\"name\":\"Volcans d\u2019Afrique, par Jacques-Marie Bardintzeff\",\"isPartOf\":{\"@id\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/wp-content\/uploads\/sites\/3\/2015\/03\/Bardintzeff.DJ_.10.13.signe_-450x287.jpg\",\"datePublished\":\"2015-03-28T11:55:34+00:00\",\"dateModified\":\"2015-03-28T11:58:02+00:00\",\"author\":{\"@id\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/#\/schema\/person\/974e1e0324e3e06f08253784e8eca61e\"},\"inLanguage\":\"fr-FR\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"fr-FR\",\"@id\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/2015\/03\/28\/volcans-dafrique\/#primaryimage\",\"url\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/wp-content\/uploads\/sites\/3\/2015\/03\/Bardintzeff.DJ_.10.13.signe_.jpg\",\"contentUrl\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/wp-content\/uploads\/sites\/3\/2015\/03\/Bardintzeff.DJ_.10.13.signe_.jpg\",\"width\":1772,\"height\":1132},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/#website\",\"url\":\"https:\/\/blogs.futura-sciences.com\/bardintzeff\/\",\"name\":\"VOLCANMANIA : le blog de Jacques-Marie BARDINTZEFF, volcanologue\",\"description\":\"Les volcans ? 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