{"id":11831,"date":"2021-07-14T12:47:07","date_gmt":"2021-07-14T10:47:07","guid":{"rendered":"http:\/\/volcanx.cluster031.hosting.ovh.net\/?page_id=11831"},"modified":"2021-07-15T12:26:12","modified_gmt":"2021-07-15T10:26:12","slug":"les-changements-topographiques","status":"publish","type":"page","link":"https:\/\/volcanofoundation.org\/fr\/renforcer-la-connaissance-des-risques\/monitoring\/les-changements-topographiques\/","title":{"rendered":"LES CHANGEMENTS TOPOGRAPHIQUES"},"content":{"rendered":"<div id=\"av_section_1\" class=\"avia-section av-av_section-a3505495476c97acb77226663f388d50 main_color avia-section-default avia-no-border-styling  avia-builder-el-0  el_before_av_section  avia-builder-el-first  avia-full-stretch av-parallax-section avia-bg-style-parallax av-minimum-height av-minimum-height-25 av-height-25  container_wrap fullsize\" data-section-bg-repeat=\"stretch\" data-av_minimum_height_pc=\"25\" data-av_min_height_opt=\"25\"><div class=\"av-parallax\" data-avia-parallax-ratio=\"0.3\"><div class=\"av-parallax-inner main_color avia-full-stretch\"><\/div><\/div><div class=\"container av-section-cont-open\"><main role=\"main\" itemprop=\"mainContentOfPage\" class=\"template-page content  av-content-full alpha units\"><div class=\"post-entry post-entry-type-page post-entry-11831\"><div class=\"entry-content-wrapper clearfix\">\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-av_one_fifth-25347b0a799d5b9f7058434b2a9c3182\">\n.flex_column.av-av_one_fifth-25347b0a799d5b9f7058434b2a9c3182{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div class=\"flex_column av-av_one_fifth-25347b0a799d5b9f7058434b2a9c3182 av_one_fifth  avia-builder-el-1  el_before_av_three_fifth  avia-builder-el-first  first flex_column_div av-zero-column-padding  \"><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-av_three_fifth-f7c1061df29de8cca6b42fcf455fe4a0\">\n.flex_column.av-av_three_fifth-f7c1061df29de8cca6b42fcf455fe4a0{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div class=\"flex_column av-av_three_fifth-f7c1061df29de8cca6b42fcf455fe4a0 av_three_fifth  avia-builder-el-2  el_after_av_one_fifth  el_before_av_one_fifth  flex_column_div av-zero-column-padding  \"><style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-av_textblock-8d09e837ca2380e6bdc85d849f6641d9\">\n#top .av_textblock_section.av-av_textblock-8d09e837ca2380e6bdc85d849f6641d9 .avia_textblock{\ncolor:#ffffff;\n}\n<\/style>\n<section class=\"av_textblock_section av-av_textblock-8d09e837ca2380e6bdc85d849f6641d9 \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock av_inherit_color\" itemprop=\"text\"><div class=\"h2-cinta-programas\">\n<h1 style=\"text-align: center; font-size: 2.5em;\">RENFORCER LA CONNAISSANCE DES RISQUES<\/h1>\n<\/div>\n<\/div><\/section><br>\n<section class=\"av_textblock_section av-av_textblock-820f97e5aca1e77a0a12cd8a6430c9f2 \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock\" itemprop=\"text\"><p class=\"p-cinta-programas\" style=\"text-align: center; background: #f5312a !important;\">POURQUOI LA FONDATION EST N&Eacute;E ?<span class=\"flecha-donativo\" style=\"vertical-align: inherit;\"> &gt;<\/span><\/p>\n<\/div><\/section><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-av_one_fifth-f7c1061df29de8cca6b42fcf455fe4a0\">\n.flex_column.av-av_one_fifth-f7c1061df29de8cca6b42fcf455fe4a0{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div class=\"flex_column av-av_one_fifth-f7c1061df29de8cca6b42fcf455fe4a0 av_one_fifth  avia-builder-el-5  el_after_av_three_fifth  avia-builder-el-last  flex_column_div av-zero-column-padding  \"><\/div>\n\n<\/div><\/div><\/main><!-- close content main element --><\/div><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-k3yaxsym-b831a12c8acddceb21a18cbb360fd41d\">\n.avia-section.av-k3yaxsym-b831a12c8acddceb21a18cbb360fd41d{\nbackground-color:#000000;\nbackground-image:unset;\n}\n.avia-section.av-k3yaxsym-b831a12c8acddceb21a18cbb360fd41d .av-section-color-overlay{\nopacity:0.9;\nbackground-color:#000000;\n}\n<\/style>\n<div id=\"av_section_2\" class=\"avia-section av-k3yaxsym-b831a12c8acddceb21a18cbb360fd41d main_color avia-section-default avia-no-border-styling  avia-builder-el-6  el_after_av_section  el_before_av_textblock  avia-bg-style-fixed av-section-color-overlay-active container_wrap fullsize\"><div class=\"av-section-color-overlay-wrap\"><div class=\"av-section-color-overlay\"><\/div><div class=\"container av-section-cont-open\"><div class=\"template-page content  av-content-full alpha units\"><div class=\"post-entry post-entry-type-page post-entry-11831\"><div class=\"entry-content-wrapper clearfix\">\n<div class=\"flex_column_table av-a5p0bb-0286912bb6bfb93801b9fa33860921b2 sc-av_one_full av-equal-height-column-flextable\">\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-a5p0bb-0286912bb6bfb93801b9fa33860921b2\">\n.flex_column.av-a5p0bb-0286912bb6bfb93801b9fa33860921b2{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div class=\"flex_column av-a5p0bb-0286912bb6bfb93801b9fa33860921b2 av_one_full  avia-builder-el-7  avia-builder-el-no-sibling  first flex_column_table_cell av-equal-height-column av-align-middle av-zero-column-padding  \"><style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-joihkone-69e81b3ac324ed7c1268b0d71e700013\">\n#top .av_textblock_section.av-joihkone-69e81b3ac324ed7c1268b0d71e700013 .avia_textblock{\nfont-size:18px;\ncolor:#ffffff;\n}\n\n@media only screen and (min-width: 768px) and (max-width: 989px){ \n#top .av_textblock_section.av-joihkone-69e81b3ac324ed7c1268b0d71e700013 .avia_textblock{\nfont-size:16px;\n}\n}\n\n@media only screen and (min-width: 480px) and (max-width: 767px){ \n#top .av_textblock_section.av-joihkone-69e81b3ac324ed7c1268b0d71e700013 .avia_textblock{\nfont-size:16px;\n}\n}\n\n@media only screen and (max-width: 479px){ \n#top .av_textblock_section.av-joihkone-69e81b3ac324ed7c1268b0d71e700013 .avia_textblock{\nfont-size:16px;\n}\n}\n<\/style>\n<section class=\"av_textblock_section av-joihkone-69e81b3ac324ed7c1268b0d71e700013 \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock av_inherit_color\" itemprop=\"text\"><blockquote>\n<p><a href=\"http:\/\/www.undrr.org\"><strong>LES DISASTERS NE SONT PAS NATURELS<\/strong><\/a>, ils sont construits socialement, par manque de pr&eacute;paration, de pr&eacute;vention, de travail d&rsquo;att&eacute;nuation, d&rsquo;&eacute;ducation et de suivi. <a class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;CE&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Abr&eacute;viation de &amp;quot;l&amp;#039;&egrave;re commune&amp;quot; ou &amp;quot;l&amp;#039;&egrave;re actuelle&amp;quot;. CE se r&eacute;f&egrave;re &agrave; l&amp;#039;ann&eacute;e &eacute;coul&eacute;e depuis le d&eacute;but de l&amp;#039;&egrave;re actuelle dans le calendrier julien ou gr&eacute;gorien, par exemple l&amp;#039;ann&eacute;e civile. L&amp;#039;&egrave;re pr&eacute;c&eacute;dente est appel&eacute;e &amp;quot;Avant l&amp;#039;&egrave;re actuelle&amp;quot; ou BCE.&lt;\/div&gt;\"  href=\"https:\/\/volcanofoundation.org\/fr\/glossary\/ce-fr\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>Ce<\/a> sont des risques ou des dangers naturels qui ont un impact sur les soci&eacute;t&eacute;s vuln&eacute;rables. Les connaissances aident &agrave; <strong>r&eacute;duire la vuln&eacute;rabilit&eacute; sociale<\/strong> et <strong>structurale<\/strong> afin d&rsquo;avoir des soci&eacute;t&eacute;s plus <strong>r&eacute;silientes<\/strong>!<\/p>\n<\/blockquote>\n<\/div><\/section><\/div><\/div><!--close column table wrapper. Autoclose: 1 -->\n<\/div><\/div><\/div><!-- close content main div --><\/div><\/div><\/div><div id=\"after_section_2\" class=\"main_color av_default_container_wrap container_wrap fullsize\"><div class=\"container av-section-cont-open\"><div class=\"template-page content  av-content-full alpha units\"><div class=\"post-entry post-entry-type-page post-entry-11831\"><div class=\"entry-content-wrapper clearfix\">\n<section class=\"av_textblock_section av-kqt9jd5e-cd33964ef4e3b772df7fef522b816d29 \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock\" itemprop=\"text\"><h2>Les mod&egrave;les num&eacute;riques d&rsquo;&eacute;l&eacute;vation (MNE) permettent de cartographier les modifications de la topographie d&rsquo;un volcan<\/h2>\n<\/div><\/section>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-kqt9ln1w-f6affe7cdeee6be02fc225bbc4bc5689\">\n#top .hr.av-kqt9ln1w-f6affe7cdeee6be02fc225bbc4bc5689{\nmargin-top:15px;\nmargin-bottom:15px;\n}\n.hr.av-kqt9ln1w-f6affe7cdeee6be02fc225bbc4bc5689 .hr-inner{\nwidth:100%;\nborder-color:#d8d8d8;\n}\n<\/style>\n<div class=\"hr av-kqt9ln1w-f6affe7cdeee6be02fc225bbc4bc5689 hr-custom  avia-builder-el-10  el_after_av_textblock  el_before_av_three_fifth  hr-center hr-icon-no\"><span class=\"hr-inner inner-border-av-border-thin\"><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-1wlhzr6-8cc129343b9618e21784b665a1361b31\">\n.flex_column.av-1wlhzr6-8cc129343b9618e21784b665a1361b31{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div class=\"flex_column av-1wlhzr6-8cc129343b9618e21784b665a1361b31 av_three_fifth  avia-builder-el-11  el_after_av_hr  el_before_av_two_fifth  first flex_column_div av-zero-column-padding  \"><p><section class=\"av_textblock_section av-kqt9tgn4-955ae44a3b12f5f76d41e08b4c147261 \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock\" itemprop=\"text\"><p>L&rsquo;observation et la mesure des changements de la forme de la surface d&rsquo;un volcan (topographie) aident les scientifiques &agrave; comprendre les processus qui provoquent &agrave; la fois <a title=\"EROSION &amp;amp ; SEDIMENT\" href=\"http:\/\/volcanx.cluster031.hosting.ovh.net\/fr\/?page_id=11736\">la croissance et l&rsquo;&eacute;rosion des formes de relief<\/a>. Les scientifiques cr&eacute;ent des cartes tr&egrave;s pr&eacute;cises de la surface du sol appel&eacute;es mod&egrave;les num&eacute;riques d&rsquo;&eacute;l&eacute;vation (MNE). Deux ou plusieurs MNE couvrant la m&ecirc;me zone sont utilis&eacute;s pour surveiller les changements topographiques de plusieurs volcans am&eacute;ricains. En comparant des MNE r&eacute;alis&eacute;s &agrave; des moments diff&eacute;rents, les scientifiques peuvent calculer le volume de <a class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;LAVE&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Terme g&eacute;n&eacute;ral d&eacute;signant le magma (roche en fusion) qui a fait &eacute;ruption &agrave; la surface de la Terre et qui conserve son int&eacute;grit&eacute; sous forme de masse fluide ou visqueuse, plut&ocirc;t que d&amp;#039;exploser en fragments.&lt;\/div&gt;\"  href=\"https:\/\/volcanofoundation.org\/fr\/glossary\/lave-fr\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>lave<\/a> &eacute;ject&eacute; ou le taux de croissance du <a class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;D&Ocirc;ME&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Masse de lave visqueuse, souvent en forme de bloc, extrud&eacute;e d&amp;#039;un &eacute;vent.&lt;\/div&gt;\"  href=\"https:\/\/volcanofoundation.org\/fr\/glossary\/dome-fr\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>d&ocirc;me<\/a> d&rsquo;un volcan actif, surveiller les changements au niveau des glaciers, mesurer l&rsquo;&eacute;paisseur des coul&eacute;es de d&eacute;bris, comprendre comment les s&eacute;diments sont transport&eacute;s dans le lit d&rsquo;une rivi&egrave;re ou d&rsquo;un cours d&rsquo;eau, et surveiller les changements de forme du canal.<\/p>\n<p>Les MNE sont g&eacute;n&eacute;r&eacute;s &agrave; partir de mesures topographiques tridimensionnelles effectu&eacute;es &agrave; l&rsquo;aide de techniques de t&eacute;l&eacute;d&eacute;tection, <a class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;CE&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Abr&eacute;viation de &amp;quot;l&amp;#039;&egrave;re commune&amp;quot; ou &amp;quot;l&amp;#039;&egrave;re actuelle&amp;quot;. CE se r&eacute;f&egrave;re &agrave; l&amp;#039;ann&eacute;e &eacute;coul&eacute;e depuis le d&eacute;but de l&amp;#039;&egrave;re actuelle dans le calendrier julien ou gr&eacute;gorien, par exemple l&amp;#039;ann&eacute;e civile. L&amp;#039;&egrave;re pr&eacute;c&eacute;dente est appel&eacute;e &amp;quot;Avant l&amp;#039;&egrave;re actuelle&amp;quot; ou BCE.&lt;\/div&gt;\"  href=\"https:\/\/volcanofoundation.org\/fr\/glossary\/ce-fr\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>ce<\/a> qui signifie que les dispositifs de mesure ou les capteurs ne sont pas en contact direct avec les objets mesur&eacute;s. Par exemple, les MNE peuvent &ecirc;tre r&eacute;alis&eacute;s &agrave; partir de photographies ou d&rsquo;images satellites superpos&eacute;es prises de la surface du sol ou avec des instruments qui capturent des mesures d&rsquo;&eacute;l&eacute;vation &agrave; haute r&eacute;solution &agrave; l&rsquo;aide de lasers.<\/p>\n<h3>Les MNE aident les scientifiques &agrave; localiser les sites de surveillance id&eacute;aux et &agrave; produire des cartes des risques volcaniques.<\/h3>\n<p>Sur plusieurs volcans, une analyse topographique utilisant les techniques du <strong>Syst&egrave;me d&rsquo;information g&eacute;ographique<\/strong> (SIG) a &eacute;t&eacute; utilis&eacute;e pour d&eacute;terminer les emplacements appropri&eacute;s pour l&rsquo;installation des stations d&rsquo;instruments de surveillance. Les calculs SIG sont utilis&eacute;s pour cartographier les voies de transmission radio pour les donn&eacute;es &agrave; envoyer des sites de surveillance aux bureaux de l&rsquo;Observatoire des volcans, pour d&eacute;terminer l&rsquo;emplacement optimal pour l&rsquo;interaction du soleil avec les panneaux solaires, pour identifier les zones d&rsquo;atterrissage des h&eacute;licopt&egrave;res et pour mesurer la hauteur des canop&eacute;es des arbres.<\/p>\n<p><strong>La mod&eacute;lisation<\/strong> est tr&egrave;s importante pour comprendre les risques volcaniques. Ces mod&egrave;les utilisent les MNE comme surface de base pour les simulations informatiques des &eacute;coulements pyroclastiques, des avalanches de d&eacute;bris, des lahars, des inondations et du transport s&eacute;dimentaire des rivi&egrave;res. Les mod&egrave;les permettent aux scientifiques de produire des cartes des risques volcaniques, de pr&eacute;voir les inondations dues aux pluies, aux chutes de neige et aux d&eacute;bordements de lacs, et de r&eacute;duire les impacts de l&rsquo;accumulation de s&eacute;diments dans les rivi&egrave;res et les ruisseaux.<\/p>\n<\/div><\/section><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-kqta1i5b-107d1a9c40127944f7fe3b907c4f1f41\">\n#top .hr.hr-invisible.av-kqta1i5b-107d1a9c40127944f7fe3b907c4f1f41{\nheight:30px;\n}\n<\/style>\n<\/p><div class=\"hr av-kqta1i5b-107d1a9c40127944f7fe3b907c4f1f41 hr-invisible  avia-builder-el-13  el_after_av_textblock  avia-builder-el-last \"><span class=\"hr-inner \"><span class=\"hr-inner-style\"><\/span><\/span><\/div><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-1iz7j36-2c9786a9f3f90bd1396461500bfb925f\">\n.flex_column.av-1iz7j36-2c9786a9f3f90bd1396461500bfb925f{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div class=\"flex_column av-1iz7j36-2c9786a9f3f90bd1396461500bfb925f av_two_fifth  avia-builder-el-14  el_after_av_three_fifth  el_before_av_three_fifth  flex_column_div av-zero-column-padding  \"><p>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-kqtcpnnn-595b4e1bcf06d7b7efd58487f7ca5b63\">\n.avia-image-container.av-kqtcpnnn-595b4e1bcf06d7b7efd58487f7ca5b63 img.avia_image{\nbox-shadow:none;\n}\n.avia-image-container.av-kqtcpnnn-595b4e1bcf06d7b7efd58487f7ca5b63 .av-image-caption-overlay-center{\ncolor:#ffffff;\n}\n<\/style>\n<\/p><div class=\"avia-image-container av-kqtcpnnn-595b4e1bcf06d7b7efd58487f7ca5b63 av-styling- avia-align-center  avia-builder-el-15  el_before_av_textblock  avia-builder-el-first \" itemprop=\"image\" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/ImageObject\"><div class=\"avia-image-container-inner\"><div class=\"avia-image-overlay-wrap\"><img decoding=\"async\" fetchpriority=\"high\" class=\"wp-image-11835 avia-img-lazy-loading-not-11835 avia_image \" src=\"https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/dome-building-episode-2004-2008-mount-st-helens.jpg\" alt=\"\" title=\"dome-building-episode-2004-2008-mount-st-helens\" height=\"1648\" width=\"1000\" itemprop=\"thumbnailUrl\" srcset=\"https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/dome-building-episode-2004-2008-mount-st-helens.jpg 1000w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/dome-building-episode-2004-2008-mount-st-helens-182x300.jpg 182w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/dome-building-episode-2004-2008-mount-st-helens-625x1030.jpg 625w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/dome-building-episode-2004-2008-mount-st-helens-768x1266.jpg 768w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/dome-building-episode-2004-2008-mount-st-helens-932x1536.jpg 932w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/dome-building-episode-2004-2008-mount-st-helens-910x1500.jpg 910w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/dome-building-episode-2004-2008-mount-st-helens-428x705.jpg 428w\" sizes=\"(max-width: 1000px) 100vw, 1000px\"\/><\/div><\/div><\/div><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-kqtcpuh7-d8db4528b4900c045b62972c54904769\">\n#top .av_textblock_section.av-kqtcpuh7-d8db4528b4900c045b62972c54904769 .avia_textblock{\nfont-size:14px;\n}\n<\/style>\n<section class=\"av_textblock_section av-kqtcpuh7-d8db4528b4900c045b62972c54904769 \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock\" itemprop=\"text\"><p><em>L&rsquo;&eacute;pisode de construction du <a class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;D&Ocirc;ME&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Masse de lave visqueuse, souvent en forme de bloc, extrud&eacute;e d&amp;#039;un &eacute;vent.&lt;\/div&gt;\"  href=\"https:\/\/volcanofoundation.org\/fr\/glossary\/dome-fr\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>d&ocirc;me<\/a> de 2004-2008 au mont Saint Helens peut &ecirc;tre observ&eacute; et mesur&eacute; avec ces deux mod&egrave;les num&eacute;riques d&rsquo;&eacute;l&eacute;vation (MNE) d&eacute;velopp&eacute;s avant et apr&egrave;s l&rsquo;&eacute;pisode &eacute;ruptif.<\/em><\/p>\n<\/div><\/section><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-14hay76-b9bade6c53b94b7d00ae79f4a86820fd\">\n#top .hr.hr-invisible.av-14hay76-b9bade6c53b94b7d00ae79f4a86820fd{\nheight:30px;\n}\n<\/style>\n<div class=\"hr av-14hay76-b9bade6c53b94b7d00ae79f4a86820fd hr-invisible  avia-builder-el-17  el_after_av_textblock  avia-builder-el-last \"><span class=\"hr-inner \"><span class=\"hr-inner-style\"><\/span><\/span><\/div><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-5qmflpq-289c3c39428682440e1f78a14e5dd324\">\n.flex_column.av-5qmflpq-289c3c39428682440e1f78a14e5dd324{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div class=\"flex_column av-5qmflpq-289c3c39428682440e1f78a14e5dd324 av_three_fifth  avia-builder-el-18  el_after_av_two_fifth  el_before_av_two_fifth  first flex_column_div av-zero-column-padding  \"><section class=\"av_textblock_section av-kqtqzo54-137a8364c2f7e4ac750aadc513a9eb82 \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock\" itemprop=\"text\"><h3>Les photographies num&eacute;riques sont un moyen bon march&eacute; et rapide de cr&eacute;er des MNE.<\/h3>\n<p>Dans un processus appel&eacute; photogramm&eacute;trie, les scientifiques du PHV prennent des photographies num&eacute;riques en superposition d&rsquo;un volcan, qui peuvent &ecirc;tre prises depuis l&rsquo;air ou le sol. Gr&acirc;ce aux r&eacute;cents progr&egrave;s de la technologie des cam&eacute;ras et des ordinateurs, ces images sont utilis&eacute;es pour construire des MNE rapidement et avec pr&eacute;cision. Cette m&eacute;thode est similaire &agrave; la technique plus ancienne consistant &agrave; utiliser des cam&eacute;ras st&eacute;r&eacute;o analogiques et &agrave; comparer des paires de photographies a&eacute;riennes superpos&eacute;es prises au m&ecirc;me moment. La collecte et le traitement des photographies pour cr&eacute;er des MNE peuvent &ecirc;tre effectu&eacute;s &agrave; un co&ucirc;t relativement faible.<br>\n<strong>Les lasers peuvent &ecirc;tre utilis&eacute;s pour cartographier la surface du sol sous la v&eacute;g&eacute;tation.<\/strong><\/p>\n<p>La technologie de d&eacute;tection et de t&eacute;l&eacute;m&eacute;trie par la lumi&egrave;re (lidar) utilise des scanners laser pour mesurer l&rsquo;&eacute;l&eacute;vation de la surface du sol, qui est utilis&eacute;e pour g&eacute;n&eacute;rer des MNE &agrave; tr&egrave;s haute r&eacute;solution. Les lasers sont capables de p&eacute;n&eacute;trer le couvert forestier jusqu&rsquo;au sol, de sorte que, contrairement aux m&eacute;thodes de photogramm&eacute;trie, les cartes r&eacute;alis&eacute;es &agrave; l&rsquo;aide du lidar r&eacute;v&egrave;lent des caract&eacute;ristiques de la surface terrestre qui sont masqu&eacute;es par les photographies num&eacute;riques prises dans des zones &agrave; v&eacute;g&eacute;tation dense ou foresti&egrave;res.<\/p>\n<p>Les MNE lidar ont &eacute;t&eacute; utilis&eacute;s pour localiser des failles jusqu&rsquo;alors inconnues, cartographier des d&eacute;p&ocirc;ts de coul&eacute;es pyroclastiques et des eaux souterraines. La plupart des scanners lidar utilisent des lasers proches de l&rsquo;infrarouge qui sont absorb&eacute;s par l&rsquo;eau, <a class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;CE&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Abr&eacute;viation de &amp;quot;l&amp;#039;&egrave;re commune&amp;quot; ou &amp;quot;l&amp;#039;&egrave;re actuelle&amp;quot;. CE se r&eacute;f&egrave;re &agrave; l&amp;#039;ann&eacute;e &eacute;coul&eacute;e depuis le d&eacute;but de l&amp;#039;&egrave;re actuelle dans le calendrier julien ou gr&eacute;gorien, par exemple l&amp;#039;ann&eacute;e civile. L&amp;#039;&egrave;re pr&eacute;c&eacute;dente est appel&eacute;e &amp;quot;Avant l&amp;#039;&egrave;re actuelle&amp;quot; ou BCE.&lt;\/div&gt;\"  href=\"https:\/\/volcanofoundation.org\/fr\/glossary\/ce-fr\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>ce<\/a> qui permet aux scientifiques de cartographier les caract&eacute;ristiques des eaux de surface telles que les sources, les rivi&egrave;res et les lacs.<\/p>\n<\/div><\/section><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-39k1nbi-955ccf39f1329f46b6bb95a7ab1193e4\">\n#top .hr.hr-invisible.av-39k1nbi-955ccf39f1329f46b6bb95a7ab1193e4{\nheight:30px;\n}\n<\/style>\n<div class=\"hr av-39k1nbi-955ccf39f1329f46b6bb95a7ab1193e4 hr-invisible  avia-builder-el-20  el_after_av_textblock  avia-builder-el-last \"><span class=\"hr-inner \"><span class=\"hr-inner-style\"><\/span><\/span><\/div><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-2trvoq6-c5814f587a08533aab8205f385a0be50\">\n.flex_column.av-2trvoq6-c5814f587a08533aab8205f385a0be50{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div class=\"flex_column av-2trvoq6-c5814f587a08533aab8205f385a0be50 av_two_fifth  avia-builder-el-21  el_after_av_three_fifth  avia-builder-el-last  flex_column_div av-zero-column-padding  \"><p>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-kqtq6km7-96c6b232861e1f857a4196214a6315cb\">\n.avia-image-container.av-kqtq6km7-96c6b232861e1f857a4196214a6315cb img.avia_image{\nbox-shadow:none;\n}\n.avia-image-container.av-kqtq6km7-96c6b232861e1f857a4196214a6315cb .av-image-caption-overlay-center{\ncolor:#ffffff;\n}\n<\/style>\n<\/p><div class=\"avia-image-container av-kqtq6km7-96c6b232861e1f857a4196214a6315cb av-styling- avia-align-center  avia-builder-el-22  el_before_av_textblock  avia-builder-el-first \" itemprop=\"image\" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/ImageObject\"><div class=\"avia-image-container-inner\"><div class=\"avia-image-overlay-wrap\"><img decoding=\"async\" fetchpriority=\"high\" class=\"wp-image-11838 avia-img-lazy-loading-not-11838 avia_image \" src=\"https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/digital-elevation-model.jpg\" alt=\"\" title=\"digital-elevation-model\" height=\"1475\" width=\"1140\" itemprop=\"thumbnailUrl\" srcset=\"https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/digital-elevation-model.jpg 1140w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/digital-elevation-model-232x300.jpg 232w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/digital-elevation-model-796x1030.jpg 796w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/digital-elevation-model-768x994.jpg 768w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/digital-elevation-model-545x705.jpg 545w\" sizes=\"(max-width: 1140px) 100vw, 1140px\"\/><\/div><\/div><\/div><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-kqtq6xrn-48627c4a9ffbba4a53951da875f446da\">\n#top .av_textblock_section.av-kqtq6xrn-48627c4a9ffbba4a53951da875f446da .avia_textblock{\nfont-size:14px;\n}\n<\/style>\n<section class=\"av_textblock_section av-kqtq6xrn-48627c4a9ffbba4a53951da875f446da \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock\" itemprop=\"text\"><p><em>L&rsquo;autoroute 504 est repr&eacute;sent&eacute;e en haut &agrave; droite.<\/em><\/p>\n<\/div><\/section><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-2e2igoe-9119e9a646b57209b89efa73fb3b9eb6\">\n#top .hr.hr-invisible.av-2e2igoe-9119e9a646b57209b89efa73fb3b9eb6{\nheight:30px;\n}\n<\/style>\n<div class=\"hr av-2e2igoe-9119e9a646b57209b89efa73fb3b9eb6 hr-invisible  avia-builder-el-24  el_after_av_textblock  el_before_av_image \"><span class=\"hr-inner \"><span class=\"hr-inner-style\"><\/span><\/span><\/div><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-kqtr9bos-71ff3c73c594d21673e6e804ef5a9a85\">\n.avia-image-container.av-kqtr9bos-71ff3c73c594d21673e6e804ef5a9a85 img.avia_image{\nbox-shadow:none;\n}\n.avia-image-container.av-kqtr9bos-71ff3c73c594d21673e6e804ef5a9a85 .av-image-caption-overlay-center{\ncolor:#ffffff;\n}\n<\/style>\n<div class=\"avia-image-container av-kqtr9bos-71ff3c73c594d21673e6e804ef5a9a85 av-styling- avia-align-center  avia-builder-el-25  el_after_av_hr  el_before_av_hr \" itemprop=\"image\" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/ImageObject\"><div class=\"avia-image-container-inner\"><div class=\"avia-image-overlay-wrap\"><img decoding=\"async\" fetchpriority=\"high\" class=\"wp-image-11841 avia-img-lazy-loading-not-11841 avia_image \" src=\"https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/lidar-images-shastina-cone.jpg\" alt=\"\" title=\"lidar-images-shastina-cone\" height=\"752\" width=\"1140\" itemprop=\"thumbnailUrl\" srcset=\"https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/lidar-images-shastina-cone.jpg 1140w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/lidar-images-shastina-cone-300x198.jpg 300w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/lidar-images-shastina-cone-1030x679.jpg 1030w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/lidar-images-shastina-cone-768x507.jpg 768w, https:\/\/volcanofoundation.org\/wp-content\/uploads\/2021\/07\/lidar-images-shastina-cone-705x465.jpg 705w\" sizes=\"(max-width: 1140px) 100vw, 1140px\"\/><\/div><\/div><\/div><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-1jik4jy-ad5a2aa6b839ef2898ac6cf7d56cffa7\">\n#top .hr.hr-invisible.av-1jik4jy-ad5a2aa6b839ef2898ac6cf7d56cffa7{\nheight:30px;\n}\n<\/style>\n<div class=\"hr av-1jik4jy-ad5a2aa6b839ef2898ac6cf7d56cffa7 hr-invisible  avia-builder-el-26  el_after_av_image  el_before_av_textblock \"><span class=\"hr-inner \"><span class=\"hr-inner-style\"><\/span><\/span><\/div><br>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-kqtrbmk5-8ac24eba9a05677c33f4fec27dc5b372\">\n#top .av_textblock_section.av-kqtrbmk5-8ac24eba9a05677c33f4fec27dc5b372 .avia_textblock{\nfont-size:14px;\n}\n<\/style>\n<section class=\"av_textblock_section av-kqtrbmk5-8ac24eba9a05677c33f4fec27dc5b372 \" itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/CreativeWork\"><div class=\"avia_textblock\" itemprop=\"text\"><p><em>Images lidar du c&ocirc;ne Shastina, flanc ouest du mont Shasta, Californie. Les d&eacute;tails des coul&eacute;es de <a class=\"glossaryLink\"  aria-describedby=\"tt\"  data-cmtooltip=\"&lt;div class=glossaryItemTitle&gt;LAVE&lt;\/div&gt;&lt;div class=glossaryItemBody&gt;Terme g&eacute;n&eacute;ral d&eacute;signant le magma (roche en fusion) qui a fait &eacute;ruption &agrave; la surface de la Terre et qui conserve son int&eacute;grit&eacute; sous forme de masse fluide ou visqueuse, plut&ocirc;t que d&amp;#039;exploser en fragments.&lt;\/div&gt;\"  href=\"https:\/\/volcanofoundation.org\/fr\/glossary\/lave-fr\/\"  data-gt-translate-attributes='[{\"attribute\":\"data-cmtooltip\", \"format\":\"html\"}]'  tabindex='0' role='link'>lave<\/a> et d&rsquo;autres caract&eacute;ristiques superficielles sont mieux visibles sur l&rsquo;image de droite avec la v&eacute;g&eacute;tation enlev&eacute;e.<\/em><\/p>\n<\/div><\/section><\/div>\n<\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Observing and measuring changes to the surface shape of a volcano (topography) helps scientists understand the processes that cause both growth and erosion of landforms.<\/p>\n","protected":false},"author":8,"featured_media":11142,"parent":11396,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-11831","page","type-page","status-publish","has-post-thumbnail","hentry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/pages\/11831","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/comments?post=11831"}],"version-history":[{"count":0,"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/pages\/11831\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/pages\/11396"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/media\/11142"}],"wp:attachment":[{"href":"https:\/\/volcanofoundation.org\/fr\/wp-json\/wp\/v2\/media?parent=11831"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}