{"id":42709,"date":"2023-01-25T08:00:36","date_gmt":"2023-01-25T08:00:36","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=42709"},"modified":"2023-01-25T08:00:36","modified_gmt":"2023-01-25T08:00:36","slug":"azijue-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2023\/01\/25\/azijue-1\/","title":{"rendered":"The 30 August 2020 debris flow at Azijue village in Sichuan Province"},"content":{"rendered":"

The 30 August 2020 debris flow at Azijue village in Sichuan Province<\/strong><\/h4>\n

On 30 August 2020, a 3.2 million cubic metre debris flow struck Azijue in Sichuan province<\/a> in China<\/a>, killing three people and causing extensive damage to two communities, a school, the Chengdu\u2013Kunming Railway (which was closed for 14 days) and three bridges.\u00a0 In a paper just published in the journal Landslides<\/em><\/a>, Yan et al.<\/em> (2023)<\/a> have provided a comprehensive account of this interesting event.<\/p>\n

The landslide can be clearly seen on Google Earth, located at 29.150, 102.870.\u00a0 This is an image from March 2016, showing the main channel and the substantial tributary down which the landslide flowed:-<\/p>\n

\"Google

Google Earth image of the location of the Azijue debris flow, collected in March 2016.<\/em><\/p><\/div>\n

.<\/p>\n

Whilst this image shows the aftermath of the landslide, collected in November 2022:-<\/p>\n

\"Google

Google Earth image of the aftermath of the Azijue debris flow, collected in November 2022.<\/em><\/p><\/div>\n

.<\/p>\n

You should be able to compare the two images using the slider below:-<\/p>\n

\"Google\"Google<\/div>\n

.<\/p>\n

According to Yan et al.<\/em> (2023)<\/a>, the landslide was triggered by about 90 mm of rainfall in a month that had already suffered abnormally high rainfall totals.\u00a0 But there is an unusual and interesting element to this landslide disaster.\u00a0 The debris flow initiated in the upper part of the catchment and travelled down the channel.\u00a0 En route it encountered two plateaus in the channel, which can be seen in the Google Earth image below:-<\/p>\n

\"Google

Google Earth image of the aftermath of the Azijue debris flow, showing the two plateaus in the channel, collected in November 2022.<\/em><\/p><\/div>\n

.<\/p>\n

These two plateaus consisted of deposits from previous flow events.\u00a0 The first plateau caused the flow to split into three components, which then merged again upon reaching the second plateau.\u00a0 But when the flow passed the downstream edge of the second plateau, a major secondary failure occurred in the channel bed, releasing a large volume of additional debris.\u00a0 The scar from this landslide can be seen in the lower centre part of the image above.<\/p>\n

Yan et al.<\/em> (2023)<\/a> have produced a rather nice schematic diagram of the mechanism of this failure:-<\/p>\n

\"The

The mechanism of failure of the Azijue debris flow, from Yan et al. (2023)<\/a>.<\/em><\/p><\/div>\n

.<\/p>\n

Yan et al.<\/em> (2022)<\/a> attribute the damage and loss of life to this secondary landslide.<\/p>\n

The impact of the Azijue debris flow was reduced by an effective early warning system.\u00a0 Yan et al.<\/em> (2022)<\/a> note that:<\/p>\n

Most of the nearby residents were successfully evacuated due to a successful detection and early warning by the local government, which can be attributed to a specific microtopographic features of Heixiluo Gully. There were two wide and sub-horizontal platforms at the lower part of the gully that effectively reduced the kinetics of the debris mass before a major secondary landslide occurred at the end of the second platform over 2\u00a0h later. This 2-h interval gave enough time for most of the residents to escape from the final debris cascade.\u00a0<\/em><\/p>\n

This was a complex landslide event, most notably because of the in-channel secondary failure.\u00a0 Anticipating such processes is very challenging.<\/p>\n

.<\/p>\n

Reference<\/strong><\/h4>\n

Yan, K., Wang, F., Fan, G.\u00a0et al.<\/i> 2023.\u00a0 The Azijue debris flow induced by rainfall on 30 August 2020 in Ganluo County, Sichuan Province, southwestern China<\/a>. Landslides<\/i>\u00a0(2023). https:\/\/doi.org\/10.1007\/s10346-022-02022-2<\/p>\n","protected":false},"excerpt":{"rendered":"

In a paper published in the journal Landslides, Yan et al. (2023) discuss the 30 August 2020 debris flow at Azijue village in Sichuan, China, which killed three people and destroyed two villages. The losses were caused by an unusual secondary failure of ancient deposits in the channel bed.<\/p>\n","protected":false},"author":22,"featured_media":42718,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[544],"tags":[16,57,469,788,132],"class_list":["post-42709","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-review-of-a-paper","tag-china","tag-debris-flow","tag-featured","tag-review-of-a-paper-2","tag-sichuan"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/42709","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=42709"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/42709\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/42718"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=42709"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=42709"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=42709"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}