{"id":29729,"date":"2019-01-03T08:49:18","date_gmt":"2019-01-03T08:49:18","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=29729"},"modified":"2019-01-03T11:17:48","modified_gmt":"2019-01-03T11:17:48","slug":"anak-krakatau-3","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2019\/01\/03\/anak-krakatau-3\/","title":{"rendered":"Anak Krakatau: Planet Labs imagery of the aftermath of the landslide"},"content":{"rendered":"

Anak Krakatau: Planet Labs imagery of the aftermath of the landslide<\/h4>\n

Planet Labs<\/a> has now captured a high-resolution SkySat<\/a> image of the aftermath of the Anak Krakatau<\/a> landslide, which generated the deadly tsunami<\/a> shortly before Christmas.\u00a0 These images are featured on the BBC website too, with an excellent commentary from Jonathan Amos<\/a>.\u00a0 The images are spectacular, as usual.<\/p>\n

So, here is an image collected on 17th December 2018 showing the volcano shortly before the landslide.\u00a0 Note the smoking volcanic cone:-<\/p>\n

\"Anak

Planet Labs image<\/a> of Anak Krakatau prior to the landslide<\/p><\/div>\n

.<\/p>\n

I can see no signs of any precursory deformation features on the volcano, which is perhaps a little surprising.\u00a0 The second image shows the volcano after the landslide, in an image captured on 30th December 2018:-<\/p>\n

\"Anak

Planet Labs image<\/a> showing Anak Krakatau after the landslide. Image captured 30th December 2018.<\/p><\/div>\n

.<\/p>\n

This image shows the bowl-shaped landslide scar, and the new, small, bay formed by the collapse.\u00a0 There is a huge amount of sediment in the water around Anak Krakatau.\u00a0 The final image was captured using the SkySat high resolution instrument, providing the best image yet of the aftermath of the landslide:-<\/p>\n

\"Anak

Planet Labs SkySat image<\/a> of the aftermath of the Anak Krakatau landslide in Indonesia. Image captured on 2nd January 2019.<\/p><\/div>\n

.<\/p>\n

So what can we say about the landslide on Anak Krakatau?\u00a0 To me the scar appears to have a bowl shape, suggesting a complex (multi-phase?), possibly rotational (?) slip.\u00a0 However, the toe of the landslide was extremely broad (look at the alignment of the rear scarp on the far side of the scar), meaning that the slide would have been able to displace water across a very large front.\u00a0 Whilst early reports of the landslide were that it was probably submarine, the images are clear that a very large part of it (possibly the largest part) was subaerial (i.e. occurred above sea level). \u00a0 No remains of the landslide are seen – it left almost nothing behind as far as I can see – so the entire volume of 150-170 million cubic metres entered the water.\u00a0 It is unsurprising therefore that it generated a very significant tsunami in the local area.<\/p>\n

An interesting aspect is the peninsular left on the southern (nearest) part of the bay, seen in the second image of Anak Krakatau.\u00a0 This is an unusual feature for a landslide scar.\u00a0 Compare the before and after images – is the peninsular composed of harder volcanic rock (lava flow?) rather than the looser cone deposits?\u00a0 So, in this area did the landslide occur primarily in the looser deposits? Or did this peninsular form in the volcanic eruptions immediately after the landslide? Some of the radar imagery might suggest that this is the case?<\/p>\n

Comments please from those who know volcanoes well.<\/p>\n

Reference<\/h4>\n

Planet Team (2018)<\/a>. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https:\/\/www.planet.com\/<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Anak Krakatau: @planetlabs have captured excellent imagery, including a high resolution SkySat view, of the aftermath of the landslide<\/p>\n","protected":false},"author":22,"featured_media":29739,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7203],"tags":[469,141,20178,1205,314,128,107],"class_list":["post-29729","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-planet-labs","tag-featured","tag-indonesia","tag-krakatau","tag-planet-labs","tag-se-asia","tag-tsunami","tag-volcano"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/29729","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/comments?post=29729"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/29729\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/29739"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=29729"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=29729"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=29729"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}