{"id":29857,"date":"2026-09-03T08:00:50","date_gmt":"2026-09-03T06:00:50","guid":{"rendered":"https:\/\/www.laterredufutur.com\/accueil\/?p=29857"},"modified":"2026-07-31T19:29:48","modified_gmt":"2026-07-31T17:29:48","slug":"chambres-magmatiques-silice-et-gaz-la-mecanique-cachee-des-volcans-explosifs","status":"publish","type":"post","link":"https:\/\/www.laterredufutur.com\/accueil\/chambres-magmatiques-silice-et-gaz-la-mecanique-cachee-des-volcans-explosifs\/","title":{"rendered":"Chambres magmatiques, silice et gaz : la m\u00e9canique cach\u00e9e des volcans explosifs"},"content":{"rendered":"<div class=\"1665f18d14f35dd9e7566e1a8ac9a3e9\" data-index=\"1\" style=\"float: none; margin:10px 0 10px 0; text-align:center;\">\n<script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js\"><\/script>\r\n<ins class=\"adsbygoogle\"\r\n     style=\"display:block; text-align:center;\"\r\n     data-ad-layout=\"in-article\"\r\n     data-ad-format=\"fluid\"\r\n     data-ad-client=\"ca-pub-2860849627502538\"\r\n     data-ad-slot=\"3019501113\"><\/ins>\r\n<script>\r\n     (adsbygoogle = window.adsbygoogle || []).push({});\r\n<\/script>\n<\/div>\n<p style=\"text-align: left;\">Sous les volcans, le magma ne s\u00e9journe pas toujours dans une immense cavit\u00e9 remplie de roche liquide. Il circule et s\u2019accumule plut\u00f4t dans un r\u00e9seau complexe de r\u00e9servoirs, de poches, de fractures et de zones partiellement fondues que les volcanologues appellent aujourd\u2019hui un <strong>syst\u00e8me de plomberie magmatique<\/strong>.<\/p>\n<p>Dans ces r\u00e9servoirs profonds, le magma contient diff\u00e9rents \u00e9l\u00e9ments chimiques, notamment de la silice, mais aussi des substances volatiles dissoutes comme l\u2019eau, le dioxyde de carbone et le dioxyde de soufre. Lorsque la pression diminue ou que le magma \u00e9volue chimiquement, ces substances se transforment progressivement en bulles de gaz.<\/p>\n<p>C\u2019est alors que la teneur en silice devient d\u00e9terminante.<\/p>\n<h2>Qu\u2019est-ce que la silice ?<\/h2>\n<p>La silice est un compos\u00e9 form\u00e9 de silicium et d\u2019oxyg\u00e8ne, de formule chimique SiO\u2082. Elle constitue une grande partie des roches de la cro\u00fbte terrestre et entre dans la composition de presque tous les magmas.<\/p>\n<p>Tous les magmas ne contiennent cependant pas la m\u00eame quantit\u00e9 de silice :<\/p>\n<ul>\n<li>les magmas basaltiques en contiennent relativement peu ;<\/li>\n<li>les magmas and\u00e9sitiques pr\u00e9sentent une teneur interm\u00e9diaire ;<\/li>\n<li>les magmas dacitiques et rhyolitiques sont tr\u00e8s riches en silice.<\/li>\n<\/ul>\n<p>Plus un magma contient de silice, plus les structures form\u00e9es par les atomes de silicium et d\u2019oxyg\u00e8ne ont tendance \u00e0 s\u2019organiser en r\u00e9seaux complexes. Ces r\u00e9seaux freinent le d\u00e9placement du liquide magmatique et augmentent fortement sa viscosit\u00e9.<\/p>\n<p>Un magma pauvre en silice est donc g\u00e9n\u00e9ralement chaud et fluide, tandis qu\u2019un magma riche en silice est souvent plus froid, \u00e9pais et p\u00e2teux.<\/p>\n<p>La teneur en silice n\u2019est toutefois pas le seul param\u00e8tre contr\u00f4lant la viscosit\u00e9. La temp\u00e9rature, la quantit\u00e9 de cristaux et la proportion de bulles jouent \u00e9galement un r\u00f4le important.<\/p>\n<figure id=\"attachment_6122\" aria-describedby=\"caption-attachment-6122\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"6122\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/confirmation-dune-chambre-magmatique-monumentale-sous-le-yellowstone\/chambre-magmatique-yellowstone\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?fit=600%2C332&amp;ssl=1\" data-orig-size=\"600,332\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"chambre-magmatique-yellowstone\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Point chaud&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?fit=600%2C332&amp;ssl=1\" class=\"wp-image-6122 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?resize=600%2C332&#038;ssl=1\" alt=\"\" width=\"600\" height=\"332\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?w=600&amp;ssl=1 600w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?resize=300%2C166&amp;ssl=1 300w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><figcaption id=\"caption-attachment-6122\" class=\"wp-caption-text\">Point chaud<\/figcaption><\/figure>\n<h2>La silice ne cr\u00e9e pas les gaz, mais elle les emprisonne<\/h2>\n<p>Il est fr\u00e9quent de lire que la silice provoque la formation de gaz dans les chambres magmatiques. Cette formulation est incompl\u00e8te.<\/p>\n<p>La silice ne se transforme pas elle-m\u00eame en gaz. Les gaz volcaniques proviennent principalement des \u00e9l\u00e9ments volatils d\u00e9j\u00e0 pr\u00e9sents dans le magma, notamment :<\/p>\n<ul>\n<li>la vapeur d\u2019eau, ou H\u2082O ;<\/li>\n<li>le dioxyde de carbone, ou CO\u2082 ;<\/li>\n<li>le dioxyde de soufre, ou SO\u2082 ;<\/li>\n<li>le sulfure d\u2019hydrog\u00e8ne, ou H\u2082S ;<\/li>\n<li>le chlorure d\u2019hydrog\u00e8ne, ou HCl ;<\/li>\n<li>le fluorure d\u2019hydrog\u00e8ne, ou HF.<\/li>\n<\/ul>\n<p>En profondeur, la pression est si \u00e9lev\u00e9e que ces substances peuvent rester dissoutes dans le magma, un peu comme le dioxyde de carbone demeure dissous dans une bouteille de boisson gazeuse ferm\u00e9e.<\/p>\n<p>Lorsque le magma remonte, la pression diminue. Les substances volatiles deviennent alors moins solubles et commencent \u00e0 former des bulles. Ce ph\u00e9nom\u00e8ne est appel\u00e9 <strong>exsolution des gaz<\/strong>.<\/p>\n<p>Plus le magma est riche en silice et visqueux, plus ces bulles ont du mal \u00e0 remonter et \u00e0 s\u2019\u00e9chapper. Elles restent emprisonn\u00e9es, grossissent et augmentent la pression interne du syst\u00e8me.<\/p>\n<p>L\u2019USGS souligne ainsi que les gaz dissous s\u2019\u00e9chappent plus difficilement des magmas visqueux et riches en silice, ce qui explique leur tendance \u00e0 produire des \u00e9ruptions plus explosives.<\/p>\n<figure id=\"attachment_22585\" aria-describedby=\"caption-attachment-22585\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"22585\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/la-region-de-naples-a-loree-dune-catastrophe-qui-aura-lieu\/champs-phlegreens-fumerolles\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?fit=1024%2C768&amp;ssl=1\" data-orig-size=\"1024,768\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"Champs Phl\u00e9gr\u00e9ens fumerolles\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;credit Pixabay License&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?fit=800%2C600&amp;ssl=1\" class=\"wp-image-22585 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?resize=800%2C600&#038;ssl=1\" alt=\"\" width=\"800\" height=\"600\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?resize=800%2C600&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?resize=300%2C225&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?resize=80%2C60&amp;ssl=1 80w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?resize=768%2C576&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?resize=174%2C131&amp;ssl=1 174w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?resize=70%2C53&amp;ssl=1 70w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumerolles.jpg?w=1024&amp;ssl=1 1024w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-22585\" class=\"wp-caption-text\">credit Pixabay License. Fumerolles champs plegreens<\/figcaption><\/figure>\n<h2>Comment les gaz apparaissent-ils dans une chambre magmatique ?<\/h2>\n<p>Plusieurs m\u00e9canismes peuvent entra\u00eener l\u2019apparition et l\u2019accumulation de gaz.<\/p>\n<h3>La baisse de pression<\/h3>\n<p>Lorsqu\u2019un magma remonte vers la surface, la pression exerc\u00e9e par les roches qui le recouvrent diminue. L\u2019eau, le CO\u2082 et les autres substances volatiles ne peuvent plus rester enti\u00e8rement dissous.<\/p>\n<p>Des bulles apparaissent, puis augmentent de volume au fur et \u00e0 mesure de la remont\u00e9e.<\/p>\n<p>C\u2019est le m\u00eame principe que lors de l\u2019ouverture d\u2019une bouteille de champagne : la diminution brutale de pression entra\u00eene la formation et l\u2019expansion des bulles.<\/p>\n<h3>La cristallisation du magma<\/h3>\n<p>Lorsqu\u2019un magma refroidit dans un r\u00e9servoir, certains min\u00e9raux commencent \u00e0 cristalliser. Or, les mol\u00e9cules d\u2019eau et une grande partie des gaz s\u2019int\u00e8grent difficilement dans la structure de ces cristaux.<\/p>\n<p>Les substances volatiles se concentrent donc progressivement dans la partie encore liquide du magma.<\/p>\n<p>Plus la cristallisation avance, plus le liquide r\u00e9siduel peut devenir riche en silice et en gaz. \u00c0 partir d\u2019un certain seuil, les substances volatiles forment des bulles, m\u00eame si le magma ne remonte pas imm\u00e9diatement.<\/p>\n<p>Ce processus est parfois appel\u00e9 <strong>cristallisation fractionn\u00e9e<\/strong> ou <strong>second boiling<\/strong>, c\u2019est-\u00e0-dire une exsolution gazeuse provoqu\u00e9e par la cristallisation.<\/p>\n<h3>L\u2019arriv\u00e9e d\u2019un nouveau magma<\/h3>\n<p>Un magma plus chaud provenant des profondeurs peut p\u00e9n\u00e9trer dans un r\u00e9servoir plus ancien. Cette recharge magmatique peut :<\/p>\n<ul>\n<li>augmenter la temp\u00e9rature ;<\/li>\n<li>apporter de nouveaux gaz ;<\/li>\n<li>provoquer un m\u00e9lange entre plusieurs magmas ;<\/li>\n<li>remettre en mouvement des cristaux ;<\/li>\n<li>accro\u00eetre la pression dans le r\u00e9servoir.<\/li>\n<\/ul>\n<p>Le magma profond, souvent plus riche en CO\u2082, peut \u00e9galement lib\u00e9rer des gaz qui traversent le r\u00e9servoir sup\u00e9rieur. Ce transfert de gaz peut modifier la pression et la composition du magma sans qu\u2019un grand volume de magma neuf atteigne imm\u00e9diatement la surface.<\/p>\n<p>Aux Champs Phl\u00e9gr\u00e9ens, par exemple, les mod\u00e8les du syst\u00e8me magmatique prennent en compte des arriv\u00e9es de magma, la cristallisation et les \u00e9changes entre plusieurs zones de stockage.<\/p>\n<figure id=\"attachment_25556\" aria-describedby=\"caption-attachment-25556\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"25556\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/les-experts-confirment-la-ligne-de-faille-islandaise-sest-reveillee-apres-800-ans\/lave-islande-grindavik\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Lave-islande-grindavik.jpg?fit=1024%2C415&amp;ssl=1\" data-orig-size=\"1024,415\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"Lave islande grindavik\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;\u00c9ruption \u00e0 la p\u00e9riph\u00e9rie de Grindavik, le 14 janvier 2024. (D\u00e9partement islandais de la protection civile et de la gestion des urgences\/AFP\/Getty Images)&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Lave-islande-grindavik.jpg?fit=800%2C324&amp;ssl=1\" class=\"wp-image-25556 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Lave-islande-grindavik.jpg?resize=800%2C324&#038;ssl=1\" alt=\"\" width=\"800\" height=\"324\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Lave-islande-grindavik.jpg?resize=800%2C324&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Lave-islande-grindavik.jpg?resize=300%2C122&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Lave-islande-grindavik.jpg?resize=768%2C311&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Lave-islande-grindavik.jpg?w=1024&amp;ssl=1 1024w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-25556\" class=\"wp-caption-text\">\u00c9ruption \u00e0 la p\u00e9riph\u00e9rie de Grindavik, le 14 janvier 2024. (D\u00e9partement islandais de la protection civile et de la gestion des urgences\/AFP\/Getty Images)<\/figcaption><\/figure>\n<h3>L\u2019assimilation des roches environnantes<\/h3>\n<p>En remontant ou en s\u00e9journant dans la cro\u00fbte terrestre, le magma peut chauffer, faire fondre ou assimiler une partie des roches qui l\u2019entourent.<\/p>\n<p>Si ces roches contiennent de l\u2019eau, des carbonates ou des mati\u00e8res riches en carbone, leur \u00e9chauffement peut lib\u00e9rer davantage de vapeur d\u2019eau ou de CO\u2082.<\/p>\n<p>Cette assimilation peut \u00e9galement enrichir le magma en silice et augmenter sa viscosit\u00e9.<\/p>\n<h2>Le r\u00f4le fondamental de la viscosit\u00e9<\/h2>\n<p>Dans un magma fluide, les bulles peuvent relativement facilement remonter, fusionner et lib\u00e9rer leurs gaz \u00e0 la surface. Le volcan peut alors d\u00e9gazer de mani\u00e8re continue par des fumerolles, un lac de lave ou des explosions mod\u00e9r\u00e9es.<\/p>\n<p>Dans un magma visqueux, les bulles restent prisonni\u00e8res. Leur expansion transforme progressivement le magma en une mousse tr\u00e8s comprim\u00e9e.<\/p>\n<p>Si la pression d\u00e9passe la r\u00e9sistance du magma et des roches environnantes, plusieurs ph\u00e9nom\u00e8nes peuvent se produire :<\/p>\n<ul>\n<li>ouverture de fractures ;<\/li>\n<li>rupture du bouchon obstruant le conduit ;<\/li>\n<li>fragmentation brutale du magma ;<\/li>\n<li>\u00e9mission d\u2019un panache de cendres ;<\/li>\n<li>formation de coul\u00e9es pyroclastiques ;<\/li>\n<li>effondrement d\u2019un d\u00f4me de lave ;<\/li>\n<li>dans les cas extr\u00eames, effondrement d\u2019une caldeira.<\/li>\n<\/ul>\n<p>L\u2019\u00e9ruption d\u00e9pend n\u00e9anmoins aussi de la vitesse de remont\u00e9e du magma, de la g\u00e9om\u00e9trie du conduit, du nombre de cristaux et de la capacit\u00e9 du syst\u00e8me \u00e0 d\u00e9gazer. Un magma riche en silice n\u2019explose donc pas syst\u00e9matiquement. Il peut parfois produire une lente extrusion de lave tr\u00e8s \u00e9paisse ou construire un d\u00f4me.<\/p>\n<figure id=\"attachment_23117\" aria-describedby=\"caption-attachment-23117\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"23117\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/les-experts-mettent-en-garde-contre-un-possible-tsunami-a-la-palma-quen-est-il-reellement\/cumbre-vieja-coulee-lave\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?fit=1800%2C1013&amp;ssl=1\" data-orig-size=\"1800,1013\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"cumbre vieja coul\u00e9e lave\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?fit=800%2C450&amp;ssl=1\" class=\"wp-image-23117 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?resize=800%2C450&#038;ssl=1\" alt=\"\" width=\"800\" height=\"450\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?resize=800%2C450&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?resize=300%2C169&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?resize=768%2C432&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?resize=1536%2C864&amp;ssl=1 1536w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?resize=580%2C326&amp;ssl=1 580w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?resize=174%2C98&amp;ssl=1 174w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/cumbre-vieja-coulee-lave.jpg?w=1800&amp;ssl=1 1800w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-23117\" class=\"wp-caption-text\">Cumbre vieja<\/figcaption><\/figure>\n<h2>Les diff\u00e9rents types de magmas<\/h2>\n<h3>Le magma basaltique<\/h3>\n<p>Le magma basaltique contient g\u00e9n\u00e9ralement moins d\u2019environ 52 \u00e0 53 % de silice. Il est chaud, souvent compris entre approximativement 1 000 et 1 200 \u00b0C, et relativement fluide.<\/p>\n<p>Les gaz peuvent s\u2019en \u00e9chapper plus facilement. Les \u00e9ruptions sont donc souvent effusives, avec :<\/p>\n<ul>\n<li>coul\u00e9es de lave ;<\/li>\n<li>fontaines de lave ;<\/li>\n<li>lacs de lave ;<\/li>\n<li>projections de scories ;<\/li>\n<li>explosions stromboliennes.<\/li>\n<\/ul>\n<p>Les volcans boucliers sont fr\u00e9quemment aliment\u00e9s par ce type de magma. Le Smithsonian d\u00e9crit ces volcans comme de vastes \u00e9difices aux pentes faibles, principalement construits par des coul\u00e9es de lave peu visqueuses et relativement pauvres en silice.<\/p>\n<p><strong>Exemples :<\/strong><\/p>\n<ul>\n<li>K\u012blauea, \u00e0 Hawa\u00ef ;<\/li>\n<li>Mauna Loa, \u00e0 Hawa\u00ef ;<\/li>\n<li>Piton de la Fournaise, \u00e0 La R\u00e9union ;<\/li>\n<li>Nyiragongo, en R\u00e9publique d\u00e9mocratique du Congo ;<\/li>\n<li>Fagradalsfjall, en Islande ;<\/li>\n<li>Etna, en Sicile, bien que son activit\u00e9 puisse aussi devenir explosive.<\/li>\n<\/ul>\n<p>Un magma basaltique n\u2019est pas forc\u00e9ment inoffensif. Une remont\u00e9e rapide, une forte concentration de gaz ou une interaction avec de l\u2019eau peut produire des explosions puissantes. Les recherches de l\u2019INGV montrent d\u2019ailleurs que m\u00eame un magma basaltique relativement fluide peut se fragmenter au cours d\u2019une activit\u00e9 explosive.<\/p>\n<figure id=\"attachment_16608\" aria-describedby=\"caption-attachment-16608\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"16608\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/eruption-volcanique-a-hawai-les-gaz-toxiques-plus-a-craindre-encore-que-les-risques-dexplosion\/hawaiian-volcano-kilauea\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2018\/05\/hawaiian-volcano-kilauea.jpg?fit=900%2C602&amp;ssl=1\" data-orig-size=\"900,602\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"hawaiian-volcano-kilauea\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2018\/05\/hawaiian-volcano-kilauea.jpg?fit=800%2C535&amp;ssl=1\" class=\"wp-image-16608 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2018\/05\/hawaiian-volcano-kilauea.jpg?resize=800%2C535&#038;ssl=1\" alt=\"\" width=\"800\" height=\"535\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2018\/05\/hawaiian-volcano-kilauea.jpg?resize=800%2C535&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2018\/05\/hawaiian-volcano-kilauea.jpg?resize=300%2C201&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2018\/05\/hawaiian-volcano-kilauea.jpg?resize=768%2C514&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2018\/05\/hawaiian-volcano-kilauea.jpg?w=900&amp;ssl=1 900w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-16608\" class=\"wp-caption-text\">Kilauea Hawa\u00ef<\/figcaption><\/figure>\n<h3>Le magma and\u00e9sitique<\/h3>\n<p>Le magma and\u00e9sitique contient approximativement entre 53 et 63 % de silice. Sa viscosit\u00e9 est interm\u00e9diaire et ses gaz s\u2019\u00e9chappent moins facilement que dans un magma basaltique.<\/p>\n<p>Il est caract\u00e9ristique de nombreux stratovolcans situ\u00e9s dans les zones de subduction.<\/p>\n<p>Il peut produire :<\/p>\n<ul>\n<li>explosions vulcaniennes ;<\/li>\n<li>panaches de cendres ;<\/li>\n<li>coul\u00e9es pyroclastiques ;<\/li>\n<li>d\u00f4mes de lave ;<\/li>\n<li>lahars ;<\/li>\n<li>coul\u00e9es de lave \u00e9paisses.<\/li>\n<\/ul>\n<p><strong>Exemples :<\/strong><\/p>\n<ul>\n<li>V\u00e9suve, en Italie ;<\/li>\n<li>Etna, lors de certaines phases ;<\/li>\n<li>Merapi, en Indon\u00e9sie ;<\/li>\n<li>Semeru, en Indon\u00e9sie ;<\/li>\n<li>Sakurajima, au Japon ;<\/li>\n<li>Popocat\u00e9petl, au Mexique ;<\/li>\n<li>Volc\u00e1n de Fuego, au Guatemala ;<\/li>\n<li>Mont Fuji, au Japon ;<\/li>\n<li>Mont Rainier, aux \u00c9tats-Unis.<\/li>\n<\/ul>\n<figure id=\"attachment_22075\" aria-describedby=\"caption-attachment-22075\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"22075\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/letna-en-effervescence-depuis-quelques-mois\/etna-3\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?fit=2048%2C1536&amp;ssl=1\" data-orig-size=\"2048,1536\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"etna\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;credit twitter Enza Tomasello&lt;br \/&gt;\n@EnzaTomasello&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?fit=800%2C600&amp;ssl=1\" class=\"wp-image-22075 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?resize=800%2C600&#038;ssl=1\" alt=\"\" width=\"800\" height=\"600\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?resize=800%2C600&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?resize=300%2C225&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?resize=80%2C60&amp;ssl=1 80w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?resize=768%2C576&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?resize=1536%2C1152&amp;ssl=1 1536w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?resize=174%2C131&amp;ssl=1 174w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?resize=70%2C53&amp;ssl=1 70w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/02\/etna.jpg?w=2048&amp;ssl=1 2048w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-22075\" class=\"wp-caption-text\">credit twitter Enza Tomasello<br \/>Etna @EnzaTomasello<\/figcaption><\/figure>\n<h3>Le magma dacitique<\/h3>\n<p>Le magma dacitique est plus riche en silice, g\u00e9n\u00e9ralement autour de 63 \u00e0 69 %. Il est tr\u00e8s visqueux, se d\u00e9place lentement et retient efficacement les gaz.<\/p>\n<p>Il forme souvent des d\u00f4mes instables. Lorsque ces d\u00f4mes s\u2019effondrent, ils peuvent produire des coul\u00e9es pyroclastiques extr\u00eamement rapides.<\/p>\n<p><strong>Exemples :<\/strong><\/p>\n<ul>\n<li>mont Saint Helens, aux \u00c9tats-Unis ;<\/li>\n<li>mont Pinatubo, aux Philippines ;<\/li>\n<li>Soufri\u00e8re Hills, \u00e0 Montserrat ;<\/li>\n<li>mont Unzen, au Japon ;<\/li>\n<li>Novarupta, en Alaska ;<\/li>\n<li>Chait\u00e9n, au Chili, dont le magma est parfois class\u00e9 entre dacite et rhyolite.<\/li>\n<\/ul>\n<figure id=\"attachment_12153\" aria-describedby=\"caption-attachment-12153\" style=\"width: 637px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"12153\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/il-y-a-36-ans-le-mont-st-helens-explosait-et-aujourdhui-que-se-passe-t-il\/mont-st-helens\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/05\/mont-st-helens.jpg?fit=637%2C426&amp;ssl=1\" data-orig-size=\"637,426\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"mont-st-helens\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/05\/mont-st-helens.jpg?fit=637%2C426&amp;ssl=1\" class=\"wp-image-12153 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/05\/mont-st-helens.jpg?resize=637%2C426&#038;ssl=1\" alt=\"\" width=\"637\" height=\"426\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/05\/mont-st-helens.jpg?w=637&amp;ssl=1 637w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/05\/mont-st-helens.jpg?resize=300%2C201&amp;ssl=1 300w\" sizes=\"auto, (max-width: 637px) 100vw, 637px\" \/><figcaption id=\"caption-attachment-12153\" class=\"wp-caption-text\">Mont saint Helens<\/figcaption><\/figure>\n<h3>Le magma rhyolitique<\/h3>\n<p>Le magma rhyolitique contient g\u00e9n\u00e9ralement plus de 69 % de silice. Il peut \u00eatre des milliers \u00e0 des milliards de fois plus visqueux qu\u2019un magma basaltique selon sa temp\u00e9rature, sa teneur en cristaux et son \u00e9tat de d\u00e9gazage.<\/p>\n<p>Les gaz y sont particuli\u00e8rement difficiles \u00e0 \u00e9vacuer. Ces magmas peuvent provoquer certaines des \u00e9ruptions les plus explosives connues :<\/p>\n<ul>\n<li>explosions pliniennes ;<\/li>\n<li>immenses panaches de cendres ;<\/li>\n<li>nu\u00e9es ardentes ;<\/li>\n<li>d\u00e9p\u00f4ts d\u2019ignimbrites ;<\/li>\n<li>effondrements de caldeiras ;<\/li>\n<li>\u00e9ruptions de tr\u00e8s grand volume.<\/li>\n<\/ul>\n<p><strong>Exemples :<\/strong><\/p>\n<ul>\n<li>Yellowstone, aux \u00c9tats-Unis ;<\/li>\n<li>Taup\u014d, en Nouvelle-Z\u00e9lande ;<\/li>\n<li>Toba, en Indon\u00e9sie ;<\/li>\n<li>Campi Flegrei ou Champs Phl\u00e9gr\u00e9ens, en Italie ;<\/li>\n<li>Long Valley, aux \u00c9tats-Unis ;<\/li>\n<li>La Garita, aux \u00c9tats-Unis ;<\/li>\n<li>Chait\u00e9n, au Chili ;<\/li>\n<li>certains volcans de la zone de Taup\u014d en Nouvelle-Z\u00e9lande.<\/li>\n<\/ul>\n<p><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"11349\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/le-bruit-de-fond-sismique-ambiant-revele-la-structure-du-systeme-volcanique-actif-de-toba\/chambre-magmatique-toba\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/chambre-magmatique-toba.jpg?fit=622%2C504&amp;ssl=1\" data-orig-size=\"622,504\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"chambre-magmatique-toba\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/chambre-magmatique-toba.jpg?fit=622%2C504&amp;ssl=1\" class=\"aligncenter wp-image-11349 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/chambre-magmatique-toba.jpg?resize=622%2C504&#038;ssl=1\" alt=\"\" width=\"622\" height=\"504\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/chambre-magmatique-toba.jpg?w=622&amp;ssl=1 622w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/chambre-magmatique-toba.jpg?resize=300%2C243&amp;ssl=1 300w\" sizes=\"auto, (max-width: 622px) 100vw, 622px\" \/><\/p>\n<p>\u00c0 Yellowstone, la forte teneur en silice de la rhyolite augmente sa viscosit\u00e9 et peut emp\u00eacher les gaz de s\u2019\u00e9chapper facilement. Ce comportement a particip\u00e9 \u00e0 de grandes \u00e9ruptions explosives et \u00e0 l\u2019effondrement de la caldeira. Cependant, Yellowstone a \u00e9galement produit d\u2019\u00e9paisses coul\u00e9es rhyolitiques relativement effusives, d\u00e9montrant qu\u2019un magma riche en silice ne provoque pas automatiquement une explosion majeure.<\/p>\n<figure id=\"attachment_11496\" aria-describedby=\"caption-attachment-11496\" style=\"width: 700px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"11496\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/chambres-magmatiques-silice-et-gaz-la-mecanique-cachee-des-volcans-explosifs\/yellowstone-3\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/yellowstone.jpg?fit=700%2C371&amp;ssl=1\" data-orig-size=\"700,371\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"yellowstone\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/yellowstone.jpg?fit=700%2C371&amp;ssl=1\" class=\"wp-image-11496 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/yellowstone.jpg?resize=700%2C371&#038;ssl=1\" alt=\"\" width=\"700\" height=\"371\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/yellowstone.jpg?w=700&amp;ssl=1 700w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/03\/yellowstone.jpg?resize=300%2C159&amp;ssl=1 300w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><figcaption id=\"caption-attachment-11496\" class=\"wp-caption-text\">Yellowstone<\/figcaption><\/figure>\n<h2>Quels types de volcans sont les plus concern\u00e9s ?<\/h2>\n<h3>Les stratovolcans<\/h3>\n<p>Les stratovolcans sont de hauts \u00e9difices coniques constitu\u00e9s d\u2019une succession de coul\u00e9es de lave, de cendres et de mat\u00e9riaux pyroclastiques.<\/p>\n<p>Ils se trouvent surtout dans les zones de subduction, notamment autour de la ceinture de feu du Pacifique et en M\u00e9diterran\u00e9e.<\/p>\n<p>Leurs magmas and\u00e9sitiques ou dacitiques sont suffisamment visqueux pour retenir une partie des gaz. Ils peuvent alterner entre longues p\u00e9riodes de calme, croissance de d\u00f4mes, \u00e9ruptions mod\u00e9r\u00e9es et explosions majeures.<\/p>\n<p><strong>Exemples :<\/strong> V\u00e9suve, Pinatubo, mont Saint Helens, Merapi, Fuji, Popocat\u00e9petl et Krakatau.<\/p>\n<p><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"6638\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/chambres-magmatiques-silice-et-gaz-la-mecanique-cachee-des-volcans-explosifs\/vesuve-pompei\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/vesuve-pompei.jpg?fit=600%2C450&amp;ssl=1\" data-orig-size=\"600,450\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;9.9&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;DSC-W180&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;1368100242&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;18,6&quot;,&quot;iso&quot;:&quot;100&quot;,&quot;shutter_speed&quot;:&quot;0,004&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"vesuve-pompei\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/vesuve-pompei.jpg?fit=600%2C450&amp;ssl=1\" class=\"aligncenter wp-image-6638 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/vesuve-pompei.jpg?resize=600%2C450&#038;ssl=1\" alt=\"\" width=\"600\" height=\"450\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/vesuve-pompei.jpg?w=600&amp;ssl=1 600w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/vesuve-pompei.jpg?resize=80%2C60&amp;ssl=1 80w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/vesuve-pompei.jpg?resize=300%2C225&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/vesuve-pompei.jpg?resize=174%2C131&amp;ssl=1 174w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/vesuve-pompei.jpg?resize=70%2C53&amp;ssl=1 70w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><\/p>\n<h3>Les volcans \u00e0 d\u00f4me<\/h3>\n<p>Les d\u00f4mes apparaissent lorsque de la lave tr\u00e8s visqueuse s\u2019accumule au-dessus du conduit au lieu de s\u2019\u00e9couler sur de longues distances.<\/p>\n<p>Le d\u00f4me peut agir comme un bouchon. Les gaz continuent alors de s\u2019accumuler en dessous. Une explosion ou un effondrement peut d\u00e9clencher des coul\u00e9es pyroclastiques.<\/p>\n<p><strong>Exemples :<\/strong> Soufri\u00e8re Hills, Unzen, Merapi, mont Saint Helens et Chait\u00e9n.<\/p>\n<figure id=\"attachment_18402\" aria-describedby=\"caption-attachment-18402\" style=\"width: 864px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"18402\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/eruption-du-volcan-merapi-en-indonesie\/merapi-volcan\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/02\/merapi-volcan.jpg?fit=864%2C576&amp;ssl=1\" data-orig-size=\"864,576\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"merapi-volcan\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/02\/merapi-volcan.jpg?fit=800%2C533&amp;ssl=1\" class=\"wp-image-18402 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/02\/merapi-volcan.jpg?resize=864%2C576&#038;ssl=1\" alt=\"\" width=\"864\" height=\"576\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/02\/merapi-volcan.jpg?w=864&amp;ssl=1 864w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/02\/merapi-volcan.jpg?resize=300%2C200&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/02\/merapi-volcan.jpg?resize=768%2C512&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/02\/merapi-volcan.jpg?resize=800%2C533&amp;ssl=1 800w\" sizes=\"auto, (max-width: 864px) 100vw, 864px\" \/><figcaption id=\"caption-attachment-18402\" class=\"wp-caption-text\">Volcan merapi<\/figcaption><\/figure>\n<h3>Les caldeiras<\/h3>\n<p>Une caldeira est une vaste d\u00e9pression cr\u00e9\u00e9e lorsque le toit d\u2019un r\u00e9servoir magmatique s\u2019effondre apr\u00e8s l\u2019\u00e9vacuation d\u2019un volume important de magma.<\/p>\n<p>Les grandes caldeiras sont fr\u00e9quemment associ\u00e9es \u00e0 des magmas riches en silice, m\u00eame si certaines caldeiras basaltiques existent \u00e9galement.<\/p>\n<p><strong>Exemples :<\/strong><\/p>\n<ul>\n<li>Yellowstone ;<\/li>\n<li>Toba ;<\/li>\n<li>Taup\u014d ;<\/li>\n<li>Champs Phl\u00e9gr\u00e9ens ;<\/li>\n<li>Crater Lake ;<\/li>\n<li>Long Valley ;<\/li>\n<li>Santorin.<\/li>\n<\/ul>\n<p>L\u2019\u00e9ruption qui a form\u00e9 Crater Lake il y a environ 7 700 ans a produit d\u2019importants d\u00e9p\u00f4ts pyroclastiques avant l\u2019effondrement de la caldeira.<\/p>\n<p><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"18001\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/yellowstone-a-engendre-deux-super-eruptions-qui-ont-modifie-le-climat-mondial\/yellowstone-super-eruption\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/01\/yellowstone-super-eruption.jpg?fit=1200%2C631&amp;ssl=1\" data-orig-size=\"1200,631\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"yellowstone-super-eruption\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/01\/yellowstone-super-eruption.jpg?fit=800%2C421&amp;ssl=1\" class=\"aligncenter wp-image-18001 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/01\/yellowstone-super-eruption-800x421.jpg?resize=800%2C421&#038;ssl=1\" alt=\"\" width=\"800\" height=\"421\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/01\/yellowstone-super-eruption.jpg?resize=800%2C421&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/01\/yellowstone-super-eruption.jpg?resize=300%2C158&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/01\/yellowstone-super-eruption.jpg?resize=768%2C404&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/01\/yellowstone-super-eruption.jpg?w=1200&amp;ssl=1 1200w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><\/p>\n<h3>Les volcans boucliers<\/h3>\n<p>Ils sont principalement associ\u00e9s \u00e0 des magmas basaltiques pauvres en silice. Leur lave fluide s\u2019\u00e9tale sur de grandes distances et construit des volcans tr\u00e8s larges aux pentes faibles.<\/p>\n<p>Les gaz y sont g\u00e9n\u00e9ralement mieux \u00e9vacu\u00e9s, mais des explosions restent possibles, notamment lorsque le magma rencontre de l\u2019eau ou lorsqu\u2019une quantit\u00e9 inhabituelle de gaz s\u2019accumule.<\/p>\n<p><strong>Exemples :<\/strong> Mauna Loa, K\u012blauea, Piton de la Fournaise et certains volcans des Gal\u00e1pagos.<\/p>\n<h2>De la bulle \u00e0 l\u2019explosion<\/h2>\n<p>Lorsqu\u2019un magma riche en gaz remonte dans le conduit volcanique, les bulles prennent de plus en plus de place.<\/p>\n<p>\u00c0 faible profondeur, leur volume peut devenir si important que le magma ressemble davantage \u00e0 une mousse qu\u2019\u00e0 un liquide homog\u00e8ne. Les parois s\u00e9parant les bulles s\u2019amincissent jusqu\u2019\u00e0 se rompre.<\/p>\n<p>Le magma se fragmente alors en :<\/p>\n<ul>\n<li>cendres ;<\/li>\n<li>lapilli ;<\/li>\n<li>ponces ;<\/li>\n<li>blocs volcaniques.<\/li>\n<\/ul>\n<p>Les gaz en expansion acc\u00e9l\u00e8rent ces fragments vers la surface. C\u2019est le m\u00e9canisme fondamental d\u2019une \u00e9ruption explosive.<\/p>\n<p>La violence de l\u2019\u00e9ruption d\u00e9pend de la vitesse avec laquelle le magma se fragmente, du d\u00e9bit dans le conduit et de la capacit\u00e9 des gaz \u00e0 s\u2019\u00e9chapper avant la rupture.<\/p>\n<p><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"13597\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/forte-eruption-explosive-du-volcan-aso-au-japon-depuis-janvier-1989\/aso-volcano-eruption-cendres-2\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/10\/aso-volcano-eruption-cendres-1.jpg?fit=800%2C519&amp;ssl=1\" data-orig-size=\"800,519\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"aso-volcano-eruption-cendres\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/10\/aso-volcano-eruption-cendres-1.jpg?fit=800%2C519&amp;ssl=1\" class=\"aligncenter wp-image-13597 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/10\/aso-volcano-eruption-cendres-1.jpg?resize=800%2C519&#038;ssl=1\" alt=\"\" width=\"800\" height=\"519\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/10\/aso-volcano-eruption-cendres-1.jpg?w=800&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/10\/aso-volcano-eruption-cendres-1.jpg?resize=300%2C195&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/10\/aso-volcano-eruption-cendres-1.jpg?resize=768%2C498&amp;ssl=1 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><\/p>\n<h2>Les cons\u00e9quences possibles<\/h2>\n<h3>Les panaches de cendres<\/h3>\n<p>Une \u00e9ruption explosive peut envoyer des cendres \u00e0 plusieurs kilom\u00e8tres ou dizaines de kilom\u00e8tres d\u2019altitude.<\/p>\n<p>Ces cendres peuvent :<\/p>\n<ul>\n<li>perturber le trafic a\u00e9rien ;<\/li>\n<li>endommager les moteurs ;<\/li>\n<li>contaminer l\u2019eau ;<\/li>\n<li>provoquer des probl\u00e8mes respiratoires ;<\/li>\n<li>ensevelir les cultures ;<\/li>\n<li>surcharger et faire s\u2019effondrer les toitures ;<\/li>\n<li>interrompre les r\u00e9seaux \u00e9lectriques.<\/li>\n<\/ul>\n<figure id=\"attachment_12780\" aria-describedby=\"caption-attachment-12780\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"12780\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/le-volcan-islandais-hekla-pourrait-entrer-en-eruption-a-nimporte-quel-moment\/eruption-of-the-eyjafjallajokull-volcano\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/06\/hekla-volcan-islande.jpg?fit=600%2C338&amp;ssl=1\" data-orig-size=\"600,338\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;2.8&quot;,&quot;credit&quot;:&quot;Getty Images&quot;,&quot;camera&quot;:&quot;Canon EOS 5D Mark II&quot;,&quot;caption&quot;:&quot;Eruption of the Eyjafjallajokul volcano in Iceland&quot;,&quot;created_timestamp&quot;:&quot;1272748247&quot;,&quot;copyright&quot;:&quot;(c) Eric Meola&quot;,&quot;focal_length&quot;:&quot;100&quot;,&quot;iso&quot;:&quot;800&quot;,&quot;shutter_speed&quot;:&quot;8&quot;,&quot;title&quot;:&quot;Eruption of the Eyjafjallaj\\u00f6kull volcano&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"Eruption of the Eyjafjallaj\u00f6kull volcano\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Eruption of the Eyjafjallajokul volcano in Iceland&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/06\/hekla-volcan-islande.jpg?fit=600%2C338&amp;ssl=1\" class=\"wp-image-12780 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/06\/hekla-volcan-islande.jpg?resize=600%2C338&#038;ssl=1\" alt=\"\" width=\"600\" height=\"338\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/06\/hekla-volcan-islande.jpg?w=600&amp;ssl=1 600w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/06\/hekla-volcan-islande.jpg?resize=300%2C169&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/06\/hekla-volcan-islande.jpg?resize=580%2C326&amp;ssl=1 580w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2016\/06\/hekla-volcan-islande.jpg?resize=174%2C98&amp;ssl=1 174w\" sizes=\"auto, (max-width: 600px) 100vw, 600px\" \/><figcaption id=\"caption-attachment-12780\" class=\"wp-caption-text\">Eruption of the Eyjafjallajokul volcano in Iceland<\/figcaption><\/figure>\n<h3>Les coul\u00e9es pyroclastiques<\/h3>\n<p>Les coul\u00e9es pyroclastiques sont des m\u00e9langes br\u00fblants de gaz, de cendres et de blocs qui d\u00e9valent les pentes \u00e0 grande vitesse.<\/p>\n<p>Leur temp\u00e9rature peut atteindre plusieurs centaines de degr\u00e9s et leur vitesse d\u00e9passer largement celle d\u2019un v\u00e9hicule.<\/p>\n<p>Elles comptent parmi les ph\u00e9nom\u00e8nes volcaniques les plus meurtriers. Elles ont notamment d\u00e9truit Pomp\u00e9i et Herculanum en 79, Saint-Pierre de la Martinique en 1902 et plusieurs zones autour du Merapi ou de la Soufri\u00e8re Hills.<\/p>\n<figure id=\"attachment_23215\" aria-describedby=\"caption-attachment-23215\" style=\"width: 710px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"23215\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/la-palma-tremble-avec-le-plus-fort-tremblement-de-terre-jusqua-aujourdhui-48-egalement-ressenti-a-tenerife\/la-palma-volcan\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/la-palma-volcan.jpg?fit=1231%2C1388&amp;ssl=1\" data-orig-size=\"1231,1388\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;1634682045&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"la palma volcan\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;credit Pixabay&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/la-palma-volcan.jpg?fit=710%2C800&amp;ssl=1\" class=\"wp-image-23215 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/la-palma-volcan.jpg?resize=710%2C800&#038;ssl=1\" alt=\"\" width=\"710\" height=\"800\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/la-palma-volcan.jpg?resize=710%2C800&amp;ssl=1 710w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/la-palma-volcan.jpg?resize=266%2C300&amp;ssl=1 266w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/la-palma-volcan.jpg?resize=768%2C866&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/la-palma-volcan.jpg?w=1231&amp;ssl=1 1231w\" sizes=\"auto, (max-width: 710px) 100vw, 710px\" \/><figcaption id=\"caption-attachment-23215\" class=\"wp-caption-text\">La Palma credit Pixabay<\/figcaption><\/figure>\n<h3>Les d\u00f4mes et bouchons volcaniques<\/h3>\n<p>Un magma visqueux peut obstruer le conduit et former un bouchon. La pression des gaz augmente alors en dessous.<\/p>\n<p>La rupture de ce bouchon peut d\u00e9clencher une explosion lat\u00e9rale ou verticale. L\u2019effondrement d\u2019un d\u00f4me peut \u00e9galement g\u00e9n\u00e9rer des avalanches de blocs et de cendres.<\/p>\n<figure id=\"attachment_23230\" aria-describedby=\"caption-attachment-23230\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"23230\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/le-mont-aso-lun-des-plus-grands-volcans-du-japon-est-entre-en-eruption-et-a-cree-un-phenomene-insolite\/mont-aso-japon\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?fit=944%2C531&amp;ssl=1\" data-orig-size=\"944,531\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"mont aso japon\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Le mont Aso, au Japon, le 20 octobre 2021. (YASUNARI ITAYAMA \/ YOMIURI \/ AFP)&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?fit=800%2C450&amp;ssl=1\" class=\"wp-image-23230 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?resize=800%2C450&#038;ssl=1\" alt=\"\" width=\"800\" height=\"450\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?resize=800%2C450&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?resize=300%2C169&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?resize=768%2C432&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?resize=580%2C326&amp;ssl=1 580w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?resize=174%2C98&amp;ssl=1 174w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/mont-aso-japon.jpg?w=944&amp;ssl=1 944w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-23230\" class=\"wp-caption-text\">Le mont Aso, au Japon, le 20 octobre 2021. (YASUNARI ITAYAMA \/ YOMIURI \/ AFP)<\/figcaption><\/figure>\n<h3>Les lahars<\/h3>\n<p>Les cendres peuvent se m\u00e9langer avec des pluies intenses, des rivi\u00e8res, un lac de crat\u00e8re ou la fonte de la neige et des glaciers.<\/p>\n<p>Ces coul\u00e9es de boue volcaniques, appel\u00e9es lahars, peuvent parcourir des dizaines de kilom\u00e8tres dans les vall\u00e9es et rester dangereuses longtemps apr\u00e8s l\u2019\u00e9ruption.<\/p>\n<figure id=\"attachment_25555\" aria-describedby=\"caption-attachment-25555\" style=\"width: 700px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"25555\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/les-experts-confirment-la-ligne-de-faille-islandaise-sest-reveillee-apres-800-ans\/reykjanes-peninsule-volcanique-eruption-decembre-2023\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Reykjanes-Peninsule-Volcanique-Eruption-Decembre-2023.jpg?fit=700%2C467&amp;ssl=1\" data-orig-size=\"700,467\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;AFP or licensors&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"Reykjanes Peninsule Volcanique Eruption Decembre 2023\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;19 December 2023 eruption. ( Kristinn Magnusson\/AFP\/Getty Images)&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Reykjanes-Peninsule-Volcanique-Eruption-Decembre-2023.jpg?fit=700%2C467&amp;ssl=1\" class=\"wp-image-25555 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Reykjanes-Peninsule-Volcanique-Eruption-Decembre-2023.jpg?resize=700%2C467&#038;ssl=1\" alt=\"\" width=\"700\" height=\"467\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Reykjanes-Peninsule-Volcanique-Eruption-Decembre-2023.jpg?w=700&amp;ssl=1 700w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/01\/Reykjanes-Peninsule-Volcanique-Eruption-Decembre-2023.jpg?resize=300%2C200&amp;ssl=1 300w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><figcaption id=\"caption-attachment-25555\" class=\"wp-caption-text\">19 December 2023 eruption. ( Kristinn Magnusson\/AFP\/Getty Images)<\/figcaption><\/figure>\n<h3>Les effets climatiques<\/h3>\n<p>Lors des plus grandes \u00e9ruptions, le dioxyde de soufre peut atteindre la stratosph\u00e8re. Il s\u2019y transforme en fines particules d\u2019acide sulfurique capables de r\u00e9fl\u00e9chir une partie du rayonnement solaire.<\/p>\n<p>Une grande \u00e9ruption peut ainsi provoquer un refroidissement temporaire \u00e0 l\u2019\u00e9chelle r\u00e9gionale ou mondiale pendant plusieurs mois ou plusieurs ann\u00e9es.<\/p>\n<p>L\u2019\u00e9ruption du Pinatubo en 1991 en constitue un exemple majeur.<\/p>\n<p>Le CO\u2082 volcanique contribue lui aussi \u00e0 l\u2019effet de serre, mais ses \u00e9missions annuelles restent tr\u00e8s inf\u00e9rieures aux \u00e9missions actuelles provoqu\u00e9es par les activit\u00e9s humaines.<\/p>\n<figure id=\"attachment_23642\" aria-describedby=\"caption-attachment-23642\" style=\"width: 743px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"23642\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/tres-forte-eruption-et-tsunami-au-tonga\/explosion-volcanique-tonga\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2022\/01\/explosion-volcanique-tonga.jpg?fit=1040%2C1120&amp;ssl=1\" data-orig-size=\"1040,1120\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"explosion volcanique tonga\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2022\/01\/explosion-volcanique-tonga.jpg?fit=743%2C800&amp;ssl=1\" class=\"wp-image-23642 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2022\/01\/explosion-volcanique-tonga.jpg?resize=743%2C800&#038;ssl=1\" alt=\"\" width=\"743\" height=\"800\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2022\/01\/explosion-volcanique-tonga.jpg?resize=743%2C800&amp;ssl=1 743w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2022\/01\/explosion-volcanique-tonga.jpg?resize=279%2C300&amp;ssl=1 279w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2022\/01\/explosion-volcanique-tonga.jpg?resize=768%2C827&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2022\/01\/explosion-volcanique-tonga.jpg?w=1040&amp;ssl=1 1040w\" sizes=\"auto, (max-width: 743px) 100vw, 743px\" \/><figcaption id=\"caption-attachment-23642\" class=\"wp-caption-text\">\u00c9ruption du Tonga<\/figcaption><\/figure>\n<h2>Peut-on pr\u00e9voir une explosion gr\u00e2ce aux gaz ?<\/h2>\n<p>Les gaz constituent l\u2019un des principaux outils de surveillance volcanique.<\/p>\n<p>Les observatoires mesurent notamment :<\/p>\n<ul>\n<li>les \u00e9missions de SO\u2082 ;<\/li>\n<li>les \u00e9missions de CO\u2082 ;<\/li>\n<li>le rapport entre diff\u00e9rents gaz ;<\/li>\n<li>la temp\u00e9rature des fumerolles ;<\/li>\n<li>la chimie des sources ;<\/li>\n<li>les \u00e9missions diffuses dans les sols.<\/li>\n<\/ul>\n<p>Une hausse du CO\u2082 peut r\u00e9v\u00e9ler une arriv\u00e9e profonde de magma ou de fluides. Une augmentation du SO\u2082 peut indiquer qu\u2019un magma plus superficiel d\u00e9gaze.<\/p>\n<p>Cependant, une diminution des \u00e9missions n\u2019est pas toujours rassurante. Elle peut signifier que le syst\u00e8me s\u2019est calm\u00e9, mais aussi que le conduit s\u2019est bouch\u00e9 et que les gaz ne parviennent plus \u00e0 s\u2019\u00e9chapper.<\/p>\n<p>Les donn\u00e9es sur les gaz doivent donc \u00eatre compar\u00e9es avec :<\/p>\n<ul>\n<li>la sismicit\u00e9 ;<\/li>\n<li>le gonflement du sol ;<\/li>\n<li>les d\u00e9placements mesur\u00e9s par GPS ;<\/li>\n<li>la temp\u00e9rature ;<\/li>\n<li>les images satellites ;<\/li>\n<li>les modifications du champ gravitationnel ;<\/li>\n<li>les changements des eaux souterraines.<\/li>\n<\/ul>\n<h2>Silice \u00e9lev\u00e9e ne signifie pas automatiquement super-\u00e9ruption<\/h2>\n<p>La pr\u00e9sence d\u2019un magma riche en silice ne permet pas, \u00e0 elle seule, de pr\u00e9voir une catastrophe.<\/p>\n<p>De nombreux volcans rhyolitiques produisent de petites \u00e9ruptions, des d\u00f4mes ou des coul\u00e9es de lave \u00e9paisses. Inversement, certains magmas basaltiques peuvent g\u00e9n\u00e9rer de violentes explosions lorsqu\u2019ils sont tr\u00e8s riches en gaz ou entrent en contact avec de l\u2019eau.<\/p>\n<p>Le comportement final d\u00e9pend d\u2019une combinaison de facteurs :<\/p>\n<ul>\n<li>volume de magma disponible ;<\/li>\n<li>quantit\u00e9 de gaz ;<\/li>\n<li>pression ;<\/li>\n<li>viscosit\u00e9 ;<\/li>\n<li>temp\u00e9rature ;<\/li>\n<li>teneur en cristaux ;<\/li>\n<li>vitesse de remont\u00e9e ;<\/li>\n<li>ouverture ou obstruction des conduits ;<\/li>\n<li>interaction avec l\u2019eau ;<\/li>\n<li>architecture du syst\u00e8me magmatique.<\/li>\n<\/ul>\n<p>La silice constitue donc un facteur essentiel, mais elle n\u2019agit jamais seule.<\/p>\n<figure id=\"attachment_22580\" aria-describedby=\"caption-attachment-22580\" style=\"width: 430px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"22580\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/la-region-de-naples-a-loree-dune-catastrophe-qui-aura-lieu\/champs-phlegreens-fumees-1\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumees-1.jpg?fit=430%2C562&amp;ssl=1\" data-orig-size=\"430,562\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;1&quot;}\" data-image-title=\"Champs Phl\u00e9gr\u00e9ens fum\u00e9es 1\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumees-1.jpg?fit=430%2C562&amp;ssl=1\" class=\"wp-image-22580 size-full\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumees-1.jpg?resize=430%2C562&#038;ssl=1\" alt=\"\" width=\"430\" height=\"562\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumees-1.jpg?w=430&amp;ssl=1 430w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/06\/Champs-Phlegreens-fumees-1.jpg?resize=230%2C300&amp;ssl=1 230w\" sizes=\"auto, (max-width: 430px) 100vw, 430px\" \/><figcaption id=\"caption-attachment-22580\" class=\"wp-caption-text\">Champs phlegreens fumerolles<\/figcaption><\/figure>\n<h2>Un \u00e9quilibre instable sous les volcans<\/h2>\n<p>Une chambre magmatique riche en silice peut rester partiellement cristallis\u00e9e pendant des si\u00e8cles ou des mill\u00e9naires. Une grande partie du syst\u00e8me peut m\u00eame avoir la consistance d\u2019une bouillie de cristaux contenant seulement une fraction de magma liquide.<\/p>\n<p>L\u2019arriv\u00e9e de magma chaud, une modification de pression ou un transfert de gaz peut n\u00e9anmoins r\u00e9activer certaines zones.<\/p>\n<p>Lorsque les gaz trouvent des fractures ouvertes, le volcan peut d\u00e9gazer sans produire d\u2019\u00e9ruption majeure. Lorsqu\u2019ils restent bloqu\u00e9s dans un magma visqueux, la pression augmente et le risque d\u2019explosion devient plus important.<\/p>\n<p>Ainsi, la dangerosit\u00e9 d\u2019un volcan ne d\u00e9pend pas seulement de la quantit\u00e9 de magma pr\u00e9sente sous l\u2019\u00e9difice. Elle d\u00e9pend surtout de son \u00e9tat physique, de sa composition, de sa teneur en gaz et de la mani\u00e8re dont l\u2019ensemble du syst\u00e8me \u00e9volue.<\/p>\n<figure id=\"attachment_25781\" aria-describedby=\"caption-attachment-25781\" style=\"width: 800px\" class=\"wp-caption aligncenter\"><img data-recalc-dims=\"1\" loading=\"lazy\" decoding=\"async\" data-attachment-id=\"25781\" data-permalink=\"https:\/\/www.laterredufutur.com\/accueil\/le-volcan-ruang-entre-en-eruption-et-menace-lindonesie-dun-tsunami\/volcan-ruang\/\" data-orig-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?fit=960%2C540&amp;ssl=1\" data-orig-size=\"960,540\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;,&quot;orientation&quot;:&quot;0&quot;}\" data-image-title=\"volcan ruang\" data-image-description=\"\" data-image-caption=\"&lt;p&gt;Situ\u00e9 au nord de l&amp;rsquo;Indon\u00e9sie, le Ruang projette nuage de cendres \u00e0 plus d&amp;rsquo;un kilom\u00e8tre de hauteur dans le ciel. (BPBD Sitaro v\u00c3\u00ada AP)&lt;\/p&gt;\n\" data-large-file=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?fit=800%2C450&amp;ssl=1\" class=\"wp-image-25781 size-large\" src=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?resize=800%2C450&#038;ssl=1\" alt=\"\" width=\"800\" height=\"450\" srcset=\"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?resize=800%2C450&amp;ssl=1 800w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?resize=300%2C169&amp;ssl=1 300w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?resize=768%2C432&amp;ssl=1 768w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?resize=580%2C326&amp;ssl=1 580w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?resize=174%2C98&amp;ssl=1 174w, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2024\/04\/volcan-ruang.webp?w=960&amp;ssl=1 960w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><figcaption id=\"caption-attachment-25781\" class=\"wp-caption-text\">Situ\u00e9 au nord de l&rsquo;Indon\u00e9sie, le Ruang projette nuage de cendres \u00e0 plus d&rsquo;un kilom\u00e8tre de hauteur dans le ciel. (BPBD Sitaro v\u00c3\u00ada AP)<\/figcaption><\/figure>\n<h2>Conclusion<\/h2>\n<p>La silice est l\u2019un des principaux architectes du comportement volcanique. En cr\u00e9ant des r\u00e9seaux mol\u00e9culaires complexes dans le magma, elle augmente sa viscosit\u00e9 et limite la fuite des gaz.<\/p>\n<p>Les gaz volcaniques ne sont pas produits par la silice elle-m\u00eame. Ils proviennent principalement de l\u2019eau, du CO\u2082, du soufre et d\u2019autres substances volatiles dissoutes dans le magma. Lorsque la pression diminue ou que le magma cristallise, ces substances forment des bulles.<\/p>\n<p>Dans les magmas fluides, les bulles peuvent souvent s\u2019\u00e9chapper progressivement. Dans les magmas riches en silice, elles restent davantage emprisonn\u00e9es, augmentant la pression jusqu\u2019\u00e0 provoquer parfois la fragmentation du magma et une \u00e9ruption explosive.<\/p>\n<p>C\u2019est cette interaction entre composition chimique, cristallisation, remont\u00e9e du magma et accumulation des gaz qui explique la diff\u00e9rence entre les paisibles coul\u00e9es de lave d\u2019un volcan bouclier et les redoutables panaches, d\u00f4mes, nu\u00e9es ardentes et caldeiras des grands volcans explosifs.<\/p>\n<p>Adaptation Terra Projects&nbsp;<\/p>\n<h3><em>Sources principales<\/em><\/h3>\n<ul>\n<li><em>United States Geological Survey, Volcano Hazards Program : silice, viscosit\u00e9, gaz et styles \u00e9ruptifs.<\/em><\/li>\n<li><em>National Park Service : influence de la composition, de la temp\u00e9rature et des gaz sur les \u00e9ruptions.<\/em><\/li>\n<li><em>Smithsonian Institution, Global Volcanism Program : types de volcans et exemples d\u2019\u00e9difices volcaniques.<\/em><\/li>\n<li><em>Institut national italien de g\u00e9ophysique et de volcanologie : d\u00e9gazage des magmas basaltiques et syst\u00e8mes magmatiques.<\/em><\/li>\n<li><em>Cassidy et collaborateurs, Controls on explosive-effusive volcanic eruption styles, revue scientifique consacr\u00e9e aux m\u00e9canismes contr\u00f4lant les transitions entre \u00e9ruptions explosives et effusives.<\/em><\/li>\n<\/ul>\n<p class=\"bawpvc-ajax-counter\" data-id=\"29857\">(9)<\/p>\n<!--CusAds0-->\n<div style=\"font-size: 0px; height: 0px; line-height: 0px; margin: 0; padding: 0; clear: both;\"><\/div>","protected":false},"excerpt":{"rendered":"<p>Sous les volcans, le magma ne s\u00e9journe pas toujours dans une immense cavit\u00e9 remplie de roche liquide. Il circule et&#8230;<\/p>\n","protected":false},"author":1,"featured_media":23215,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"ngg_post_thumbnail":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[19],"tags":[950,6255,5358,1138,112,949,7960,105],"class_list":["post-29857","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-seismes-et-volcans","tag-chambre-magmatique","tag-champs-phlegreens","tag-explosif","tag-gaz","tag-lave","tag-magma","tag-silice","tag-yellowstone","wpcat-19-id"],"jetpack_publicize_connections":[],"jetpack_shortlink":"https:\/\/wp.me\/p631RN-7Lz","jetpack-related-posts":[{"id":20962,"url":"https:\/\/www.laterredufutur.com\/accueil\/augmentation-des-rayons-cosmiques-les-volcans-se-comporteraient-comme-des-chambres-a-bulles-et-deviendraient-explosif\/","url_meta":{"origin":29857,"position":0},"title":"Augmentation des rayons cosmiques, les volcans se comporteraient comme des chambres \u00e0 bulles et deviendraient explosifs","author":"Admin","date":"8 juin 2020","format":false,"excerpt":"Les volcans \u00e0 magma riche en silice et tr\u00e8s visqueux ont tendance \u00e0 produire de violentes \u00e9ruptions explosives qui provoquent des catastrophes dans les communaut\u00e9s locales et qui affectent fortement l'environnement mondial. Nous avons examin\u00e9 le moment de 11 \u00e9v\u00e9nements \u00e9ruptifs qui ont produit du magma riche en silice \u00e0\u2026","rel":"","context":"Dans &quot;Seismes\/Volcans&quot;","block_context":{"text":"Seismes\/Volcans","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/seismes-et-volcans\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/05\/volcan-rayon-cosmique.jpg?fit=1200%2C675&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/05\/volcan-rayon-cosmique.jpg?fit=1200%2C675&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/05\/volcan-rayon-cosmique.jpg?fit=1200%2C675&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/05\/volcan-rayon-cosmique.jpg?fit=1200%2C675&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2019\/05\/volcan-rayon-cosmique.jpg?fit=1200%2C675&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":26984,"url":"https:\/\/www.laterredufutur.com\/accueil\/le-volcan-uturuncu-ou-connu-sous-le-nom-de-volcan-zombie-montrerait-des-signes-de-reveil-apres-271-000-ans\/","url_meta":{"origin":29857,"position":1},"title":"Le volcan Uturuncu, connu sous le nom de volcan \u00ab zombie \u00bb, montrerait des signes de r\u00e9veil apr\u00e8s 271 000 ans. Qu&rsquo;en est-il r\u00e9ellement ?","author":"Admin","date":"9 juin 2025","format":false,"excerpt":"Un volcan bolivien, longtemps endormi, connu sous le nom d'Uturuncu, ou volcan \u00ab zombie \u00bb, montre des signes de r\u00e9veil apr\u00e8s 271 000 ans selon certains m\u00e9dias. Situ\u00e9 dans la cordill\u00e8re des Andes, il a r\u00e9cemment enregistr\u00e9 une activit\u00e9 sismique et des \u00e9missions de gaz accrues. Gr\u00e2ce \u00e0 des donn\u00e9es\u2026","rel":"","context":"Dans &quot;Seismes\/Volcans&quot;","block_context":{"text":"Seismes\/Volcans","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/seismes-et-volcans\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2025\/06\/volcan-uturuncu-2.jpg?fit=800%2C533&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2025\/06\/volcan-uturuncu-2.jpg?fit=800%2C533&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2025\/06\/volcan-uturuncu-2.jpg?fit=800%2C533&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2025\/06\/volcan-uturuncu-2.jpg?fit=800%2C533&ssl=1&resize=700%2C400 2x"},"classes":[]},{"id":26880,"url":"https:\/\/www.laterredufutur.com\/accueil\/les-scientifiques-affirment-que-quelque-chose-bouche-le-supervolcan-de-yellowstone\/","url_meta":{"origin":29857,"position":2},"title":"Les scientifiques affirment que quelque chose bouche le supervolcan de Yellowstone","author":"Admin","date":"8 mai 2025","format":false,"excerpt":"Des chercheurs ont trouv\u00e9 des preuves qu'un \u00ab bouchon \u00bb g\u00e9ant fait de magma pourrait emp\u00eacher le supervolcan du parc national de Yellowstone d'entrer en \u00e9ruption. Comme l'indique un article publi\u00e9 le mois dernier dans la revue Nature, une \u00e9quipe de chercheurs a d\u00e9couvert une \u00ab couche riche en mati\u00e8res\u2026","rel":"","context":"Dans &quot;Seismes\/Volcans&quot;","block_context":{"text":"Seismes\/Volcans","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/seismes-et-volcans\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?fit=600%2C332&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?fit=600%2C332&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?fit=600%2C332&ssl=1&resize=525%2C300 1.5x"},"classes":[]},{"id":6121,"url":"https:\/\/www.laterredufutur.com\/accueil\/confirmation-dune-chambre-magmatique-monumentale-sous-le-yellowstone\/","url_meta":{"origin":29857,"position":3},"title":"Confirmation d&rsquo;une chambre magmatique monumentale sous le Yellowstone","author":"Admin","date":"24 avril 2015","format":false,"excerpt":"Un papier vient d'\u00eatre publi\u00e9 dans la revue Science qui confirme que la chambre magmatique sous le Yellowstone est gigantesque. Un gigantesque r\u00e9servoir de magma a \u00e9t\u00e9 d\u00e9couvert et analys\u00e9 sous le super-volcan de Yellowstone aux Etats-Unis, par une \u00e9quipe de vulcanologues qui publie sa d\u00e9couverte dans la revue Science.\u2026","rel":"","context":"Dans &quot;Seismes\/Volcans&quot;","block_context":{"text":"Seismes\/Volcans","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/seismes-et-volcans\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?fit=600%2C332&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?fit=600%2C332&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/04\/chambre-magmatique-yellowstone.png?fit=600%2C332&ssl=1&resize=525%2C300 1.5x"},"classes":[]},{"id":27953,"url":"https:\/\/www.laterredufutur.com\/accueil\/lun-des-volcans-les-plus-explosifs-de-la-terre-se-remplit-tranquillement-de-magma\/","url_meta":{"origin":29857,"position":4},"title":"L&rsquo;un des volcans les plus explosifs de la Terre se remplit tranquillement de magma","author":"Admin","date":"12 avril 2026","format":false,"excerpt":"Il y a environ 7 300 ans, un volcan au large de l'\u00eele japonaise de Kyushu a d\u00e9clench\u00e9 ce qui reste la plus grande \u00e9ruption connue de l'Holoc\u00e8ne, notre \u00e9poque g\u00e9ologique actuelle. Dans une nouvelle \u00e9tude, des chercheurs r\u00e9v\u00e8lent comment l'immense chambre magmatique de ce volcan se remplit lentement, ce\u2026","rel":"","context":"Dans &quot;Seismes\/Volcans&quot;","block_context":{"text":"Seismes\/Volcans","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/seismes-et-volcans\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2026\/04\/caldeira-Kikai.webp?fit=1200%2C675&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2026\/04\/caldeira-Kikai.webp?fit=1200%2C675&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2026\/04\/caldeira-Kikai.webp?fit=1200%2C675&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2026\/04\/caldeira-Kikai.webp?fit=1200%2C675&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2026\/04\/caldeira-Kikai.webp?fit=1200%2C675&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":6723,"url":"https:\/\/www.laterredufutur.com\/accueil\/simulation-3d-de-la-chambre-magmatique-du-yellowstone\/","url_meta":{"origin":29857,"position":5},"title":"Simulation 3D de la chambre magmatique du Yellowstone","author":"Admin","date":"2 juin 2015","format":false,"excerpt":"\u00ab Pour la premi\u00e8re fois, nous avons imag\u00e9 le syst\u00e8me de plomberie volcanique continue sous Yellowstone\u00ab , explique le premier auteur Hsin-Hua Huang, \u00e9galement chercheur en g\u00e9ologie et g\u00e9ophysique. \u00ab Cela inclut la chambre magmatique sup\u00e9rieure que nous avons vu pr\u00e9c\u00e9demment, plus un r\u00e9servoir de magma dans la cro\u00fbte inf\u00e9rieure\u2026","rel":"","context":"Dans &quot;Seismes\/Volcans&quot;","block_context":{"text":"Seismes\/Volcans","link":"https:\/\/www.laterredufutur.com\/accueil\/sujets\/seismes-et-volcans\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/simulation-3d-yelowstone.jpg?fit=847%2C470&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/simulation-3d-yelowstone.jpg?fit=847%2C470&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/simulation-3d-yelowstone.jpg?fit=847%2C470&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2015\/05\/simulation-3d-yelowstone.jpg?fit=847%2C470&ssl=1&resize=700%2C400 2x"},"classes":[]}],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.laterredufutur.com\/accueil\/wp-content\/uploads\/2021\/10\/la-palma-volcan.jpg?fit=1231%2C1388&ssl=1","_links":{"self":[{"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/posts\/29857","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/comments?post=29857"}],"version-history":[{"count":8,"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/posts\/29857\/revisions"}],"predecessor-version":[{"id":29881,"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/posts\/29857\/revisions\/29881"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/media\/23215"}],"wp:attachment":[{"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/media?parent=29857"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/categories?post=29857"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laterredufutur.com\/accueil\/wp-json\/wp\/v2\/tags?post=29857"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}