29 June 2023

The 27 June 2023 landslide at Miansi, Sichuan Province, China

Posted by Dave Petley

The 27 June 2023 landslide at Miansi, Sichuan Province, China

The monsoon in Asia is now developing quickly, with heavy rainfall triggering landslides in both East and South Asia.  The most intense rainfall usually occurs later in the summer, so the current phase is likely to be just the opening act. The developing El Nino conditions and the extreme heat being recorded in many places make the monsoon quite unpredictable.

In China, some areas are already being affected by heavy rainfall.  Notably, an extreme rainfall event impacted Miansi and Weizhou townships in Wenchuan county of Sicuhan Province on 27 June 2023.  This has been reported by AP and a few other agencies, but it is less easy to find information in the Chinese media except for a brief report on Xinhua Society. It appears that the landslides killed at least seven people.

The best report that I can find is in Mandarin in thepaper.cn. This includes a series of images of what appears to have been a very large debris flow:-

The aftermath of the 27 June 2023 debris flow at Miansi and Weizhou townships in Wenchuan county.

The aftermath of the 27 June 2023 debris flow at Miansi and Weizhou townships in Wenchuan county. Image from thepaper.cn.

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The landslide appears to have been sufficiently large to be valley-blocking in the first instance, although the dam has now breached.

The article includes another image, providing detail further up the main channel, in which structural damage is clear:-

The aftermath of the 27 June 2023 debris flow at Miansi and Weizhou townships in Wenchuan county

The aftermath of the 27 June 2023 debris flow at Miansi and Weizhou townships in Wenchuan county. Image from thepaper.cn.

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I believe that the location of the place shown in the images above is [31.408, 103.529]. Google Earth imagery suggests that this is an area with many landslides prior to this heavy rainfall.  Many of those area likely to have been associated with the 2008 Wenchuan Earthquake – this area was heavily impacted by landslides in that event.  It is remarkable that elevated levels of landslide events continue to occur, 15 years after the earthquake.