25 April 2016
Espirito Santo rock joint collapses
There is an extraordinary video on Facebook showing massive collapses of sheeting joints in Espirito Santo Brazil. I cannot embed the video, but really recommend that you take a look. This is the moment of collapse:
The collapse occurred in Pancas County of Espirito Santo in an area of granite massifs. The video was posted by Heinrich Theodor Frank, who provides the following comment (this is a tidied up Google Translation):
Yesterday, in the city of Pancas (ES), something happened very scary – and was filmed! Granites and other rocks, when they change of course they do so from the outside. Successive rock levels are changed and the rock begins to form “shells” like an onion [this is exfoliation jointing].
The same process happens with whole mountains, where there is a stress relief process. There are good internet pictures of granites in arid regions, where the “shells” are well exposed because they are not hidden beneath vegetation (search for “spheroidal exfoliation”). In Pancas the “shells” of granite changed collapsed down the hill – with everything that was in them. The news is available on the network, but the footage of this is an extraordinary record of this event. After an initial collapse, the staff began to film the dust cloud and therefore, succeeded in filming the next “shells” sliding downhill. An unpublished video in the world!
The video starts after the first collapse (which has clearly generated a vast amount of dust). After a hiatus there is then a series of successive collapses as the joints unload. This is the second major collapse event:
A cliff collapse from SW China
I don’t think I have come across this one before (but it is now hard to keep track!). It is a dramatic cliff collapse from China, but the commentary provides no additional information.
This is a classic rock topple. The slope has clearly been cut, allowing a collapse on a pre-existing set of joints. Look carefully for the was that the landslide destroys the building on the right side:
Thanks to Dave Milledge of Durham University for pointing out the Espirito Santo video.