{"id":14965,"date":"2015-04-26T08:29:01","date_gmt":"2015-04-26T08:29:01","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=14965"},"modified":"2015-04-26T09:09:08","modified_gmt":"2015-04-26T09:09:08","slug":"nepal-earthquake-2","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2015\/04\/26\/nepal-earthquake-2\/","title":{"rendered":"Landslides from the Nepal earthquake yesterday"},"content":{"rendered":"
Landslides from the Nepal Earthquake<\/h5>\n

Whilst the Nepal Earthquake is now the centre of global attention, the true pattern of loss is not yet apparent.\u00a0 As usual, the focus in the first 24 hours is on the locations that have both media presence and easy telecommunications – in this case Kathmandu.\u00a0 The impacts there are undoubtedly serious, especially for historic masonry buildings, and the city will never be the same again.\u00a0 But the true impacts of this event are going to have been felt in the rural areas to the north of the city.\u00a0 At present there is little information from those districts, but expect the picture to be tragic as it emerges over the next two days.<\/p>\n

Landslides are going to be a very real problem in those areas affected by the Nepal earthquake, and by its aftershocks.\u00a0 Indeed, just 15 minutes ago there was a very shallow M=6.8 aftershock<\/a> that is likely to have caused substantial damage in its own right, albeit in a more limited area.\u00a0 There has been some confusion about the area affected by the earthquake, and in particular the area of most intense shaking.\u00a0 This is because there is a perception that the epicentre is the centre of the earthquake, and thus that the damage should radiate away from this point.\u00a0 This is not the case.\u00a0 The earthquake energy is derived from movement on a fault (or sometimes more than one fault) – a complex three-dimensional structure that extends over a large distance.\u00a0 The epicentre is just where the rupture initiates – i.e. the location at which the fault starts to move.\u00a0 The rupture then propagates along the fault, releasing energy as it goes.\u00a0 Often the rupture propagates quite evenly away from the epicentre, in which case the epicentre is close to the centre of the earthquake-affected area.\u00a0 But at other times the rupture propagates preferentially in one direction or another.<\/p>\n

In the case of the Nepal Earthquake the rupture appears to have propagated mostly towards the east of the epicentre, not to the west.\u00a0 So the epicentre itself is at the west end of the earthquake affected zone.\u00a0 This is clear from the USGS shakemap<\/a>, which shows the epicentre as a star:<\/p>\n

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

This was good for Pokhara, but bad for Kathmandu.\u00a0 It also explains why the impacts at Everest were so serious.<\/p>\n

Possible landslides from the Nepal earthquake<\/h5>\n

The most seriously affected area from the earthquake is mountainous and remote, but there are substantial numbers of people living in the valleys and on the hillsides.\u00a0 This is a typical landscape:-<\/p>\n

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

Further to the north the mountains become higher and the slopes longer.\u00a0 Note the terracing in the fields, the steep slopes and the large numbers of houses.\u00a0 There are many substantial villages, often located high on the slopes.\u00a0 This is highly landslide-prone territory, and the impact of the earthquake in these regions is going to be dreadful. \u00a0 Some effort is already being made to analyse the likely landslide effects, although at this stage such efforts are tentative.\u00a0 Over on the EWF blog<\/a>, Alex Densmore has posted an initially analysis by Tom Robinson from the University of Canterbury<\/a> of the likely areas affected by landslides:<\/p>\n

\"Nepal<\/a>

Landslide susceptibility in the Nepal Earthquake by Tom Robinson, University of Canterbury<\/a><\/p><\/div>\n

 <\/p>\n

.<\/p>\n

There are a few things to note here.\u00a0 First, the analysis is dependent on the data quality, and you can see that there are some issues there (this is why there appears to be straight line boundaries in landslide hazard in places) – that is an important caveat.\u00a0 But the analysis is really interesting and helpful.\u00a0 It shows that to the north of Kathmandu, the very remote areas are likely to have been severely affected by landslides – but as yet there is no information from up there of course.\u00a0 And interestingly the hills to the south of Kathmandu are also badly impacted by landslides triggered by the Nepal earthquake – indeed the landslide picture might be as bad there as to the north.\u00a0 This is significant for two reasons – first, there are lots of people living in this area; and second, the roads that link Kathmandu to the outside world have to cross these hills.<\/p>\n

Tom has run a quick analysis of the main roads affected by these landslides – the impacts look to be very serious:<\/p>\n

\"Nepal<\/a>

Likely major road impacts of landslides, by Tom Robinson, University of Canterbury<\/a><\/p><\/div>\n

.<\/p>\n

Kathmandu is entirely dependent on goods being brought into the city on these roads.\u00a0 If they are badly affected by landslides then the impacts will be severe.<\/p>\n

There is a real urgency about the need to assess the actual landslide impacts, especially to the north – we need satellite imagery quickly.\u00a0 There must be a strong possibility of large valley-blocking landslides triggered by the Nepal Earthquake in the high mountains to the north- if so these will need to addressed without delay.\u00a0 The monsoon is going to be a real problem this year.<\/p>\n","protected":false},"excerpt":{"rendered":"

Landslides are likely to have been a major impact from the Nepal Earthquake. Tom Robinson at the University of Canterbury has run an initial analysis of the likely distribution<\/p>\n","protected":false},"author":22,"featured_media":14968,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[537],"tags":[23,469,503,185,66,72],"class_list":["post-14965","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-earthquake-induced-landslide","tag-earthquake","tag-featured","tag-hazard","tag-landslide","tag-nepal","tag-south-asia"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/14965","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=14965"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/14965\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/14968"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=14965"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=14965"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=14965"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}