{"id":2657,"date":"2011-02-26T07:31:06","date_gmt":"2011-02-26T07:31:06","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=2657"},"modified":"2011-02-26T07:31:06","modified_gmt":"2011-02-26T07:31:06","slug":"boulder-vs-house-landslide-losses-in-the-christchurch-earthquake","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2011\/02\/26\/boulder-vs-house-landslide-losses-in-the-christchurch-earthquake\/","title":{"rendered":"Boulder vs house – landslide losses in the Christchurch earthquake"},"content":{"rendered":"

A clearer picture is beginning to emerge of landslide losses caused by the Christchurch earthquake this week.\u00a0 Unfortunately, it is now apparent that some of the deaths were caused by rockfalls and that ongoing slope problems are likely to be a legacy of the earthquake in some areas.\u00a0 In terms of loss of life, two people are reported to have been killed<\/a> by rockfalls triggered by aftershocks as they tried to hike back to their homes in Lyttleton, and at least one person was killed by a rockfall in Sumner.<\/p>\n

A particularly badly-affected area appears to be the town of Sumner, where houses are located close to steep slopes in volcanic materials.\u00a0 Several houses were damaged by rockfalls in this area, and Star Canterbury<\/a> reports that 12 streets in the Redcliffs area have been evacuated as a result of concerns about rockfalls. 3News<\/a> reports that the concern is that further rockfalls are occurring during aftershocks (this is very possible), but also that there may be victims located under the debris.\u00a0 Probably the best depiction of this problem is this aerial image from MSNBC<\/a>:<\/p>\n

\"\"<\/a><\/p>\n

Meanwhile, the threat posed by rockfalls is probably best illustrated by this remarkable story from Lyttleton<\/a> of a house that was struck by a boulder dislodged from the slope above:<\/p>\n

\"\"<\/a><\/p>\n

The boulder in question<\/a> is now located at the bottom of the slope:<\/p>\n

\"\"<\/a><\/p>\n

Newer buildings in New Zealand are generally timber-framed and quite lightweight, but the level of damage as the boulder has passed through is interesting.\u00a0 A few things to note – first the big gouge in the ground in the first image suggests that the rock was both bouncing and rotating.\u00a0 It is this rotation that allows boulders to build huge amounts of momentum.\u00a0 Second, the boulder was clearly airborne when it passed through the house – note where the gouge stops and then the lack of damage to the floor of the house.\u00a0 And finally, the boulder is heavily weathered (i.e. it is not a fresh detachment from a rockface) and for a large part the weathered surface appears undamaged.\u00a0 Still, bearing in mind that the house was subjected to very intense shaking and the impact of this rock it has not done too badly.<\/p>\n

Finally, not really a landslide story of course, but on a related issue, as I mentioned in my earlier post <\/a>liquefaction has been a very major problem in this earthquake.\u00a0 This image from MSNBC<\/a> does illustrate remarkably the magnitude of the impacts of this process:<\/p>\n

\"\"<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

A review of the latest information about rockfalls triggered by the Christchurch earthquake in New Zealand<\/p>\n","protected":false},"author":22,"featured_media":2658,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_members_access_role":[],"_members_access_error":""},"categories":[1],"tags":[23,469,959,7,527],"class_list":["post-2657","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-earthquake","tag-featured","tag-landslide-report","tag-new-zealand","tag-rockfalls"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/2657","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=2657"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/2657\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/2658"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=2657"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=2657"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=2657"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}