At the moment the available pictures of this event are poor - no doubt much better ones will emerge tomorrow as this will be a very big story in Taiwan. The best I have been able to find so far are these picture from TVBS:
There is also a youtube video of a news report from the slide site, which you should be able to view below:
Compare the video above with this image of the site before failure to get an idea of just how large this slide is:
Interestingly, there was no recorded rainfall or earthquakes at the time of the collapse. The mechanism and nature of the failure will be very interesting.
I have been arguing for some time that Taiwan needs to start managing its slopes better. Will this finally see the authorities take some action?
Hat tip to Chingying Tsou of Kyoto University for pointing this one out and providing the links.
From the images shown here, this looks to me like a translational rock slide on a failure surface that passes close to (or through) the road surface at the 'upslope' side of the cutting. This might suggest, in the absence of any other information, that failure resulted from a combination of natural strength loss due to weathering leading to progressive failure along a structural weakness (probably a sedimentary bedding plane judging by the video images), combined with excavation to create the highway cutting and remove toe support. No distinct trigger event would be needed for such a scenario.
ReplyDeleteIt was a slide of a large mass of colluvium on a rock surface...
ReplyDeletenot the trigger. earthquake happened a day after the landslide.
ReplyDelete