19 April 2016
Drone footage of the Kumamoto earthquake landslides
Kenichi Handa from the National Building Research Organization (NBRO) in Sri Lanka, to which he has been seconded by the Ministry of Land, Infrastructure, Transport and Tourism in Japan, added a comment to my post yesterday about the Kumamoto earthquake with some very useful links to images and videos of the landslides triggered by the quake. Particularly impressive is a set of drone footage videos collected by the Geographical Survey Institute, which provide clarity about the landslides. One of the films features the very large landslide at Mimami-Aso:
The footage shows that the upper portion of the landslide is very steep, with a planar mid section:
Whilst the lower part of the slide plane is stepped:
The video also confirms that the landslide has not blocked the river.
Perhaps more interesting is drone footage of the massive flowslide that I featured yesterday:
To me this would seem to be the most interesting landslide of all. The video suggests that the landslide might have had multiple source zones on steep forested slopes, including these two:
However, the drone footage hints there are further source zone landslides upstream, such as in the top right of this image:
This is clarified by an extraordinary photograph from the Ajiko website:
Thus, there appears to be a highly concentrated set of shallow translational landslides in the upper part of the catchment. I would suspect that this must be a case of dynamic liquefaction leading to a highly mobile flow. It has probably the most beautiful runout pattern of any of the Kumamoto Earthquake landslides:
The location of this landslide can be found on the GSI online GIS platform. This is the site on Google Earth, I think:
This suggests that the landslide has occurred on the flanks of Mount Aso, the largest active volcano in Japan. I suspect therefore that this might have been a flow of volcanic ash, so technically may be a lahar.
It is increasingly clear that the Kumamoto Earthquake landslides are remarkable. More will follow in the next few days…