2 September 2009
New images of the Shiaolin landslide in Taiwan
Posted by Dave Petley
The largest landslide triggered by typhoon Morakot occurred at Shiaolin in Kiaosiung County. It is estimated that 450 people died in this landslide. Until now I have been struggling to find a decent image of the slide itself, apart from the poor quality aerial photography and drone video that I have highlighted previously. However, I have today come across the following three images on the Taiwan News website:
Click on the images for a better view in a new window.The failure is a little difficult to interpret. It is possible that it is a very large-scale translational slide, with a large about of erosion into the scarp to form the channel structure. Alternatively, there could be an element of a wedge failure here, but if so it is surprisingly deep. The slide looks to have been very high energy, and thus very destructive, in the lower part of the track.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
I'm not a geologist so I apologize for layman-speak. In the bottom photo, it looks like the more durable rocks are forming two ridges. One ridge is marked toward the top by a white outcrop, and further down I think I see a flat exposure where debris flowed along these competent rocks where the 'stream' narrows down. On the left side, I think I see three outcrops of ridge forming rocks. They are dark gray and line up nicely with the undisturbed ridge above the slide. The layers look to be dipping down to the left side in this photo.The top photo has similar instances of a 45 degree dip on the left — I think I see two distinct fault planes on the left bottom just up from the river. I do like the thought that these are thrust faults pushing to the right; the failure rode down these fault planes.However there seems to be horizontal layering at the bottom which make my first hunch hard to maintain. But these light lines seem to cut across different materials, particularly on the right side. So perhaps these are younger faults.
Thank UU have helped me with My geography A Level work lol