<\/p>\n\n\n\n
A small mountain stands in the middle of the ocean, a hill, strictly speaking. It is called Anak Krakatau<\/strong>, which roughly means “Child of Krakatau”, because a much larger mountain once stood in its place. Just like its predecessor, the Anak Krakatau can spit fire because it’s a volcano<\/strong>. Whenever it erupts and the lava flows down its flanks into the sea and the rocks it throws into the air collect on its banks, it grows a little higher and further into the sea.<\/p>\n\n\n\n If you look under the sea surface<\/strong>, you can see that the “volcano child” is not as small<\/strong> as one might have thought at first. Because just like an iceberg, only the smallest tip is visible above the ocean<\/strong>. If such a volcanic island continues to grow, various circumstances can cause it to become instable<\/strong>, similar to a sandcastle that you piled up too high<\/strong>. Sometimes a large part of the volcano slides very slowly<\/strong>, a few centimeters a year. But sometimes it gets a lot more dramatic and a whole flank collapses into the sea<\/strong> in a single fast event.<\/p>\n\n\n\n If you drop a stone into the water<\/strong>, it causes the water to move and creates small waves<\/strong>. When half a volcano slides into the ocean, the exact same thing happens, only on a bigger scale: A tsunami develops<\/strong>. This is exactly what happened a few years ago at Christmas on Anak Krakatau. A large block from the small volcano slid into the ocean, causing a tsunami that killed several hundred people<\/strong> on the surrounding islands.<\/p>\n\n\n\n Tsunamis that are triggered by earthquakes<\/strong> can usually be predicted well<\/strong> today and people can be warned in good time. With tsunamis triggered by landslides and collapsing volcanic islands, this is much more difficult<\/strong>. The problem is that it is not well understood what happens when a flank collapses into the ocean. There are many open questions; Under what circumstances do volcanic islands collapse catastrophically and when are they more likely to be stable? Is there a connection between the slow sliding of some volcanoes and their collapse?<\/strong> Is the gliding even the beginning, a warning<\/strong> of a catastrophic landslide?<\/p>\n\n\n\n For my PhD, I’m looking at the geometric shape of volcanic islands<\/strong>. It is important that I look at the entire volcanic structure – from the sea floor to the summit<\/strong>. I look at so-called DEM data for this. DEM stands for Digital Elevation Model<\/strong>, i.e. digital height maps. On land, these are obtained through very precise radar measurements from satellites<\/strong> and can be downloaded from data platforms on the Internet. However, radar waves cannot penetrate water<\/strong>, which is why so-called echo sounders are needed<\/strong> to survey the ocean. These are devices that are attached to the hull of a ship and emit a sound signal<\/strong>. The device then listens for the echo<\/strong> from the signal. It can then calculate the depth to the sea floor<\/strong> from the time it takes for the echo to get back to the ship.<\/strong><\/p>\n\n\n\n This data can also be found on special data platforms, but so far only a small part of the oceans has been mapped<\/strong> in this way. If I can find a good data set, I can determine where the base of the volcano<\/strong> is, where it ends and where the sea floor begins. I use a program I created to help me with this. Then I can calculate a lot of properties. How steep<\/strong> are the slopes? What is the area and volume<\/strong>, and how much of it is visible above the water?<\/p>\n\n\n\n I collect all this information in a database for all the volcanoes I study<\/strong>. I also gather any additional information I find in scientific publications; How old the volcano is, what material it is made of and whether it has already collapsed. I can then take a very close look at the database and find connections with the help of statistical methods<\/strong>. Perhaps very large or very steep volcanoes collapsed particularly frequently?<\/p>\n\n\n\n Of course, I can’t stop volcanoes from collapsing<\/strong> with the answers to these questions, and I don’t think anyone will ever be able to do that. So, I wouldn’t have been able to save Anak Krakatau either. But each of these answers help us to understand a little better why volcanoes sometimes creep slowly into the sea and sometimes collapse into the water rather dramatically. The more we know<\/strong> about this, the better we can assess the dangers<\/strong> and how best to protect people from them.<\/strong><\/p>\n\n\n\n <\/p>\n\n\n\n Elisa Klein<\/p>\n\n\n\n Find me here:<\/strong> A small mountain stands in the middle of the ocean, a hill, strictly speaking. It is called Anak Krakatau, which roughly means “Child of Krakatau”, because a much larger mountain once stood in its place. Just like its predecessor, the Anak Krakatau can spit fire because it’s a volcano. Whenever it erupts and the lava […]<\/p>\n","protected":false},"author":227,"featured_media":190,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-81","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-talking-science"],"_links":{"self":[{"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/posts\/81","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/users\/227"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/comments?post=81"}],"version-history":[{"count":22,"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/posts\/81\/revisions"}],"predecessor-version":[{"id":189,"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/posts\/81\/revisions\/189"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/media\/190"}],"wp:attachment":[{"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/media?parent=81"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/categories?post=81"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/oceanvoices\/wp-json\/wp\/v2\/tags?post=81"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Just like an iceberg, only the smallest tip is visible above the water.<\/strong><\/span><\/h1>\n<\/div><\/div>\n<\/div>\n<\/div>\n\n\n\n
Under which circumstances do volcanic islands collapse catastrophically and when are they more likely to be stable?<\/strong><\/span><\/h1>\n\n\n\n
So far, only a small part of the oceans has been mapped.<\/strong><\/span><\/h1>\n\n\n\n
\n\n\n\n
Pre-Collapse Website<\/a>
Twitter: @Elisa_Klein_<\/a>
And on Research Gate<\/a> <\/p>\n","protected":false},"excerpt":{"rendered":"