The Sucun rockslide in Lishui, China in 2016

The Sucun rockslide (also known as the Su Village rockslide) killed 27 people in Lishui, Zhejiang in China on 28th September 2016.  Apart from the significant losses, this was a notable landslide for the fact that it was caught on video from two different perspectives:

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I reported on the landslide at the time, and indicated that this was a site with substantial signs of instability well before the final failure event.  This landslide has now been analysed and written up in the journal Landslides (Ouyang et al. 2018).  The paper includes a detailed analysis of the rockslide, including this before and after image of the site, and analysis of the pattern of movement:-

The Sucun rockslide in Chine in September 2016. Illustration from Ouyang et al. 2018 showing before and after imagery of the landslide, and detail on its pattern of movement.

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The authors conclude that the rockslide occurred during a period of heavy rainfall – a nearby weather station recorded 114.6 mm of rainfall in the 24 hours leading up to the landslide, close to the average monthly total for September, brought by the remains of Typhoon Megi.  They demonstrate using successive satellite images that the slope showed clear signs of deformation in the years leading up to the collapse, and that there were local reports of rockfalls.  The day before the landslide a rockfall led to the evacuation of the village; sadly some of the residents returned to their homes prior to the rockslide.

The Sucun rockslide had a volume of about 400,000 m³.  It is interesting to note that figure (c) in the image above indicates that the landslide deposited sediment along much of its track, which seems quite unusual.  I am not quite sure how this squares with the description in the paper, which describes entrainment along the track.

Its good to see a detailed analysis of this important rockslide – there are many lessons to learn about the recognition of pre-failure evolution of a rockslope.

Reference

Ouyang, C., Zhao, W., Xu, Q. et al. 2018. Failure mechanisms and characteristics of the 2016 catastrophic rockslide at Su village, Lishui, China. Landslides. https://doi.org/10.1007/s10346-018-0985-1