12 July 2018
Images of the disastrous landslides in Japan this week
Over the last few days Japan has suffered from record levels of rainfall, triggering large numbers of landslides. In total at least 200 people have been killed in flood and landslide events.
To give an idea of the scale of this event, Planet Labs have published a before an after image pair of just one part of the affected area. This is the “after” image, showing the landslides around Yasuuracho Chuo, near to Hiroshima:-
The image above shows multiple shallow slides, many of which appear to have transitioned into high mobility channelised debris flows. These are highly dangerous. Japanese news agencies have been publishing images that illustrate the scale of these landslides. The image below, published in The Mainichi, shows shallow slides at Uwajima in Ehime Prefecture. It may be no coincidence that the landslides have occurred in areas that have had heavy modification of their vegetation:
Another image, also from The Mainichi, shows the impact of channelised flows in structures:-
Meanwhile, the image below, published by Kyodo (via The Mainichi) shows a shallow slide in a very steep, deeply weather slope in Kitakyushu, southwestern Japan:-
The Japan Times has this spectacular image of the failure of a slope above a highway. Note that this is an engineered slope; the displaced slope reinforcement can be seen in the landslide debris. As such this is a failure of design:-
And the image below shows the impact of two flow type landslides on a highway in Otoyo in Kochi Prefecture:-
At least 47 sections of expressway have been damaged by the landslides.
This is without doubt the most significant landslide event of 2018 to date. I’m sure more information will emerge in due course. The landslide research community in Japan is very large, and they are assiduous in documenting large landslide events. Japan is of course no stranger to massive landslide events , caused by both exceptional rainfall and earthquakes.
Planet Team (2017). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://api.planet.com