31 July 2023

Two new mudflow videos

Posted by Dave Petley

Two new mudflow videos

Around the world, and not just in the Northern Hemisphere, intense rainfall events are triggering landslides and inducing significant flooding.  This is likely to be a combination of the normal annual climatic cycle and the effects of the highest atmospheric and sea surface temperatures on record.

The figure below, from Froude and Petley (2018), shows the global pattern of fatal landslides, using pentads (five day blocks) through the year.  The data shows that the global peak occurs in the period between the 40th and 45th pentads, which is 15 July to 13 August.  However, the event rate this year appears to be exceptionally high.

Mean number of landslides per pentad through the annual cycle for all rainfall-triggered landslides, by geographical region. The 20th pentad is the 6–10 April, the 40th pentad is 15–19 July and the 60th pentad is 23–27 October.

The mean number of landslides per pentad through the annual cycle for all rainfall-triggered landslides, by geographical region. The 20th pentad is the 6–10 April, the 40th pentad is 15–19 July and the 60th pentad is 23–27 October. From Froude and Petley (2018)

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There are many landslides being caught on video – for the most part I try to Tweet these (@davepetley) rather than including them here, but some are proving to be quite spectacular.  Two good examples have emerged over the weekend. The first is a very powerful mudflow that was triggered by heavy rainfall in Nan’An in Fujian Province in China, posted on 29 July 2023:-

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Nan’An is at [24.95, 118.38], although the precise location of this very violent mudflow is unclear.

Heavy rainfall is being reported in the area of Beijing today (31 July 2023), with some remarkable videos of flooding. Rainstorm warnings are in place across much of northern China. This event was caused by the remains of Typhoon Doksuri. Fortunately, no-one was killed but economic losses could exceed $500 million.

Meanwhile, a mudflow is a river in Valdoara in South Tyrol, Italy on 29 July 2023 has also been posted to Twitter:-

https://twitter.com/alex_le_bars/status/1685369384783536128

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The location appears to be [46.75107, 12.01525]. According to reports in Italian, the event was triggered by an intense thunderstorm.  Damage was caused to roads, bridges, the power infrastructure and trees.

I suspect that more videos of this type will emerge in the coming days.

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Reference

Froude, M. J. and Petley, D. N. 2018. Global fatal landslide occurrence from 2004 to 2016Natural Hazards and Earth System Sciences18, 2161-2181, https://doi.org/10.5194/nhess-18-2161-2018.